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Cardiorespiratory System (Content Map) - Anatomy & Physiology

2008-09-09T14:01:48Z

Lwyacem:

File:Respiratory System Concept Map.jpg

2008-09-09T14:00:53Z

Lwyacem: Respiratory System Concept Map

Respiratory System Concept Map

Cardiorespiratory System (Content Map) - Anatomy & Physiology

2008-09-09T14:00:17Z

Lwyacem:

Trachea - Anatomy & Physiology

2008-09-09T13:52:42Z

Lwyacem: /* Structure */

Respiration in Non-Homeotherms - Anatomy & Physiology

2008-09-09T13:25:23Z

Lwyacem:

{{toplink
|backcolour = D1EEEE
|linkpage =Cardiorespiratory System - Anatomy & Physiology
|linktext =Cardiorespiratory System
|maplink = Cardiorespiratory System (Content Map) - Anatomy & Physiology
|pagetype =Anatomy
}}
 

==Fish==

Fish live in a relatively dense and viscous fluid, which has little oxygen carrying capacity. In order to gain sufficient [[Gas Exchange - Anatomy & Physiology|gaseous exchange]] for survival, fish have developed a highly efficient system which has a large surface area, and utilises energy - the gills.

===Gills===

Gills are in the walls of both sides of the [[Pharynx - Anatomy & Physiology|pharynx]] and are composed of filaments which increase the surface area.
When a fish breaths, it takes in water into the mouth, which is then forced out through the gills.

A '''Countercurrent Exchange''' system is in place within the gills to make gaseous exchange more efficient.

==Amphibia==

In amphibian species, the [[Skin - Anatomy & Physiology|skin]] forms the major, and sometimes only respiratory organ.

The [[Skin - Anatomy & Physiology|skin]] of amphibia is:
*Thin
*Poorly keratinised
*Highly vascularised
*Moist to promote diffusion of gases

'''Aquatic''' amphibians may also have ''internal gills'' and '''Pharyngeal Slits'''.

Most Amphibia also have lungs for breathing. This contains interconnecting septa which divide the lumen into '''Faveoli''', compartments which open into a central chamber within each [[Lungs - Anatomy & Physiology|lung]].

==Reptiles==

Reptiles have a fundamentally different respiratory system to that of mammals, in that they lack a bronchial tree.

Route of Air in the Reptiliant Respiratory System:
#Air enters via nares
#[[Nasal Cavity - Anatomy & Physiology|Nasal Cavity]]
#Choana
#Glottis (base of tongue)
#Trachea
#Bronchi
#Lungs

The lungs are paired, with respiration only occuring in the cranial region.

The Respiratory surface is composed of '''Faveoli''', honeycomb shaped structures which line the walls.

In addition, reptiles have a poorly developed mucocillary escalator, and rely on body positioning to clear mucous from the respiratory system.

===Lizards===
*No diaphragm
*Simple, saclike, paired [[Lungs - Anatomy & Physiology|lungs]].
*Cranial part of lung is site of respiratory function
*Caudal part of lung forms air ''reservoir''
*Ventilation occurs via expansion and contraction of the ribs

===Snakes===
*Larynx projects medially from the floor of the mouth and is fused with the first few cartilage rings of the trachea. This forms a rigid '''Glottis''' which is highly mobile and can be displaced laterally to allow breathing during feeding.
*Tongue is fixed at the rostral point of the oral cavity.
*Generally only the right lung is present, or at least functional - ''colubrids'' have a vestigial left lung. The lung of snakes is very fragile.
*Inspiration is an active process, made possible by expansion of the ribs. It occurs approx once every 30 seconds in large, healthy snakes. Expiration is a passive prcoess.
*Snakes have no vocal cords, but are able to make hissing noises by passing air through the glottis.
*Aquatic snakes have an air sacs which serves as a bouyancy aid.

===Chelonians===
*Chelonians have adapted a '''dive reflex''' which enables them to respire anaerobically. They have extremely high levels of bicarbonate in their blood which allows them to buffer the lactic acid produced.
*Chelonians have an extremely short trachea in relation to their size.
*Chelonians have paired lungs in the '''Dorsal Cavity'''. Intestines etc lie in the '''Ventral Cavity'''. These are separated by a diaphragmatic septum which has no muscular part.
*Possess large spongy lungs which reduced 80% in size when the head and limbs are retracted inside the shell.The lungs have a single intrapulmonary bronchus which radiates in a network of bronchioles and faveoli.
*Lungs are ventilated by leg movement in terrestrial animals, and have highly developed trunk muscles to facilitate this. Aquatic species are able to respire due to the hydrostatic pressure of water, which forces air in and out of the lungs. In addition, some soft shelled chelonians are able to absorb oxygen trhough their shells and skin when submerged.

Respiration in Non-Homeotherms - Anatomy & Physiology

2008-09-09T13:15:19Z

Lwyacem:

{{toplink
|backcolour = D1EEEE
|linkpage =Cardiorespiratory System - Anatomy & Physiology
|linktext =Cardiorespiratory System
|maplink = Cardiorespiratory System (Content Map) - Anatomy & Physiology
|pagetype =Anatomy
}}
 

==Fish==

Fish live in a relatively dense and viscous fluid, which has little oxygen carrying capacity. In order to gain sufficient [[Gas Exchange - Anatomy & Physiology|gaseous exchange]] for survival, fish have developed a highly efficient system which has a large surface area, and utilises energy - the gills.

===Gills===

Gills are in the walls of both sides of the [[Pharynx - Anatomy & Physiology|pharynx]] and are composed of filaments which increase the surface area.
When a fish breaths, it takes in water into the mouth, which is then forced out through the gills.

A '''Countercurrent Exchange''' system is in place within the gills to make gaseous exchange more efficient.

==Amphibia==

In amphibian species, the [[Skin - Anatomy & Physiology|skin]] forms the major, and sometimes only respiratory organ.

The [[Skin - Anatomy & Physiology|skin]] of amphibia is:
*Thin
*Poorly keratinised
*Highly vascularised
*Moist to promote diffusion of gases

'''Aquatic''' amphibians may also have ''internal gills'' and '''Pharyngeal Slits'''.

Most Amphibia also have lungs for breathing. This contains interconnecting septa which divide the lumen into '''Faveoli''', compartments which open into a central chamber within each [[Lungs - Anatomy & Physiology|lung]].

==Reptiles==

Reptiles have a fundamentally different respiratory system to that of mammals, in that they lack a bronchial tree.

Route of Air in the Reptiliant Respiratory System:
#Air enters via nares
#[[Nasal Cavity - Anatomy & Physiology|Nasal Cavity]]
#Choana
#Glottis (base of tongue)
#Trachea
#Bronchi
#Lungs

The lungs are paired, with respiration only occuring in the cranial region.

The Respiratory surface is composed of '''Faveoli''', honeycomb shaped structures which line the walls.

In addition, reptiles have a poorly developed mucocillary escalator, and rely on body positioning to clear mucous from the respiratory system.

===Lizards===
*No diaphragm
*Simple, saclike, paired [[Lungs - Anatomy & Physiology|lungs]].
*Cranial part of lung is site of respiratory function
*Caudal part of lung forms air ''reservoir''
*Ventilation occurs via expansion and contraction of the ribs

===Snakes===
*Larynx projects medially from the floor of the mouth and is fused with the first few cartilage rings of the trachea. This forms a rigid '''Glottis''' which is highly mobile and can be displaced laterally to allow breathing during feeding.
*Tongue is fixed at the rostral point of the oral cavity.
*Generally only the right lung is present, or at least functional - ''colubrids'' have a vestigial left lung. The lung of snakes is very fragile.
*Inspiration is an active process, made possible by expansion of the ribs. It occurs approx once every 30 seconds in large, healthy snakes. Expiration is a passive prcoess.
*Snakes have no vocal cords, but are able to make hissing noises by passing air through the glottis.
*Aquatic snakes have an air sacs which serves as a bouyancy aid.

===Chelonians===
*Chelonians have adapted a '''dive reflex''' which enables them to respire anaerobically. They have extremely high levels of bicarbonate in their blood which allows them to buffer the lactic acid produced.
*Chelonians have an extremely short trachea in relation to their size.
*Have paired lungs in the '''Dorsal Cavity'''. Intestines etc lie in the '''Ventral Cavity'''. These are separated by a diaphragmatic septum which has no muscular part.
*Lungs are ventilated by leg movement in terrestrial animals, and have highly developed trunk muscles to facilitate this. Aquatic species are able to respire due to the hydrostatic pressure of water, which forces air in and out of the lungs.

Avian Respiration - Anatomy & Physiology

2008-09-09T13:05:21Z

Lwyacem:

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|linkpage =Cardiorespiratory System - Anatomy & Physiology
|linktext =Cardiorespiratory System
|maplink = Cardiorespiratory System (Content Map) - Anatomy & Physiology
|pagetype =Anatomy
}}
 

==Introduction==

The avian respiratory system contains some fundamental differences to the mammalian system.

==Avian Nasopharynx and Oropharynx==

*The nostrils of the bird, which lead into the [[Nasal cavity - Anatomy & Physiology|nasal cavity]], may have a flap of horn to protect them, known as the ''Operculum''.
*The Oral Cavity and the Nasal Cavity of the bird are interconnecting via a slit in the [[Hard Palate - Anatomy & Physiology|hard palate]] called the ''Choana''. Birds lack a [[Soft Palate - Anatomy & Physiology|soft palate]].
[[Image:Avianheadsaggitalsection.jpg|right|thumb|350px|©Nottingham 2008 ''Saggital Section of an Avian skull showing the conchae.]]
*There are Rostral, Middle and Caudal Conchae arising from the lateral wall, filling part of the [[Nasal cavity - Anatomy & Physiology|nasal cavity]].
**Rostral Conchae - Vestibular Region - lined with Stratified Squamous Epithelium
**Middle Conchae - Respiratory Region - lined with [[Respiratory Epithelium - Anatomy & Physiology|Respiratory Epithelium]].
**Caudal Conchae - [[Special Senses - Olfactory - Anatomy & Physiology|Olfactory]] Region - lined with [[Special Senses - Olfactory - Anatomy & Physiology|olfactory]] epithelium.
*The '''Infraorbital Sinus''' is a triangular cavity under the skin, rostroventral to the eye.
*Some marine birds have a ''Salt Gland'' (nasal gland) which excretes sodium.

==Avian Larynx==
*The [[Larynx - Anatomy & Physiology|larynx]] is on the floor of the [[Oral Cavity - Oropharynx - Anatomy & Physiology|oropharynx]] supported by '''Cricoid''' and paired '''Arytenoid''' Cartilages which are different in structure to those in mammals.
*There is no [[Epiglottis|Epiglottis.]]
*There are no vocal folds - birds vocalise using a [[Syrinx - Anatomy & Physiology|syrinx]].

==Avian Trachea==
*The avian [[Trachea - Anatomy & Physiology|trachea]] is composed of tightly stacked [[Bones and Cartilage - Anatomy & Physiology|cartilages]] which are shaped similarly to signet rings. These are complete with no dorsal space as in the mammalian [[Trachea - Anatomy & Physiology|trachea]]. They overlap considerably.
*The trachea can be palpated on the right side of the neck; it runs alongside the [[Oesophagus - Anatomy & Physiology|oesophagus]].
*The trachea is lined with [[Respiratory Epithelium - Anatomy & Physiology|Respiratory Epithelium]].
*The trachea bifurcates into two main [[Bronchi and bronchioles - Anatomy & Physiology|bronchi]] as in mammals. The [[Syrinx - Anatomy & Physiology|syrinx]] is formed by this terminal part of the trachea.

==Avian Lungs==
*Avian [[Lungs - Anatomy & Physiology|lungs]] are relatively compact, with a bird's lungs being approximately 50% as large as the lung of a mammal of a similar size. The lungs are unlobed and do not have the capacity to expand due to the fact that they contain cartilage.
*The lungs are positioned in the craniodorsal region of the body, and are deeply indented by both the thoracic [[Spinal Column - Anatomy & Physiology#Vertebrae and Joints|vertebrae]] and [[Ribs and Sternum - Anatomy & Physiology|ribs]].
*Birds do not have a [[Pleural cavity and membranes|pleural cavity]] as the lungs do not expand, thus the membranes are not necessary.
*One '''Primary Bronchi''' from the [[Trachea - Anatomy & Physiology|trachea]] enters each lung, narrowing as it travels through, and communicates with the '''Abdominal Air Sac'''. This bronchi gives off branches as it travels through the lung, known as '''Secondary Bronchi'''. Each of these gives off a further 400-500 '''Parabronchi''' in the walls of which, [[Gas Exchange - Anatomy & Physiology|gaseous exchange]] takes place.

==Air Sacs==
*Birds lack a [[Diaphragm - Anatomy & Physiology|diaphragm]], and their thoracic and abdominal cavities are continuous.
*The bird has a number of thin walled, easily distensible '''Air Sacs''' which can extend to approximatley 10x the volume of the [[Lungs - Anatomy & Physiology|lungs]]. These are present within body cavities, and extend into some specific [[Bones and Cartilage - Anatomy & Physiology|bones]], to take the place of [[Bone Marrow - Anatomy & Physiology|bone marrow]]. This has the added function of reducing the weight of the bone, as they are essentially filled with air.
*The air sacs create unidirectional flow of air to maximise oxygen extraction and reduce heat production during flight.
*The chicken has 8 air sacs:
**'''Cervical''' - this extends within the cervical and thoracic [[Spinal Column - Anatomy & Physiology#Vertebrae and Joints|vertebrae]].
**'''Clavicular''' - lies within the thoracic inlet, surrounding the [[Heart - Anatomy & Physiology|heart]], and within the humerus in the [[Forelimb - Anatomy & Physiology|forelimb]].
**'''Cranial Thoracic''' (x2) - these are ventral to the [[Lungs - Anatomy & Physiology|lungs]].
**'''Caudal Thoracic''' (x2) - located between the body wall and the thoracic air sacs.
**'''Abdominal''' (x2) - these are the largest air sacs and fill the caudodorsal region of the abdomen, in contact with [[Small Intestine - Anatomy & Physiology|small]] and [[Large Intestine - Anatomy & Physiology|large intestines]], [[Kidney Basic Anatomy & Physiology|kidneys]] and [[Reproductive System - Anatomy & Physiology|reproductive]] organs. In addition these airsacs utilise space within the acetabulum and synsacrum.
*The Cervical, Clavicular and Cranial Thoracic air sacs form one functional group - '''Cranial''', with the Caudal Thoracic and Abdominal Air sacs forming another, '''Caudal''' functional group.
*The air sacs have a vital role in [[Ventilation - Anatomy & Physiology|ventilation]], but do not have the capacity for [[Gas Exchange - Anatomy & Physiology|gaseous exchange]].

==Avian Ventilation==
*[[Ventilation - Anatomy & Physiology|Ventilation]] in birds is strikingly different to that of mammals in that air flows through the lungs in the same direction during both [[Ventilation - Anatomy & Physiology#Inspiration|inspiration]] and [[Ventilation - Anatomy & Physiology#Expiration|expiration]]. In addition, both the intaking of air and the expelling of air are active processes, requiring [[Muscles - Anatomy & Physiology|muscle]] contraction.
*During Inspiration, the [[Ribs and Sternum - Anatomy & Physiology|ribs]] are drawn forwards and the [[Ribs and Sternum - Anatomy & Physiology|sternum]] lowered, the Caudal air sacs receiving fresh air.
*Simultaneously, the Cranial air sacs receive air which was inhaled at the previous inhalation which is drawn from the lungs, this air has lost much of it's oxygen content.
*During Expiration, the [[Ribs and Sternum - Anatomy & Physiology|sternum]] is drawn caudal and dorsal, the air sacs are compressed, air from the caudal air sac passes through the [[Lungs - Anatomy & Physiology|lungs]], while the air in the cranial air sac leaves via the [[Trachea - Anatomy & Physiology|trachea]].
*Thus oxygenated air passes through the lungs on both [[Ventilation - Anatomy & Physiology#Inspiration|inspiration]] and [[Ventilation - Anatomy & Physiology#Expiration|expiration]].

==Avian Gas Exchange==
*Avian Gas exchange takes place not in alveoli, as in mammals, but within '''Air Capillaries''' which are extensions of the parabronchial lumen. They are an interconnecting network of loops, and closely intertwine with Blood Capillaries.
*The Air Capillaries and Blood Capillaries are arranged so that flow is ''crosscurrent''. This makes the [[Gas Exchange - Anatomy & Physiology|gaseous exchange]] which occurs from one to the other extremely efficient.

==References==

*{{citation|initiallast = Dyce|initialfirst = K.M|2last = Sack|2first = W.O|finallast = Wensing|finalfirst = C.J.G|year = 2002|title = Textbook of Veterinary Anatomy|ed =3rd|city = Philadelphia|pub = Saunders}}
*{{citation|initiallast = Sjaastad|initialfirst = O.V|2last = Hove|2first = K|finallast = Sand|finalfirst = O|year = 2004|title = Physiology of Domestic Animals|city = Oslo|pub = Scandinavian Veterinary Press}}

Avian Respiration - Anatomy & Physiology

2008-09-09T13:04:31Z

Lwyacem:

{{toplink
|backcolour = D1EEEE
|linkpage =Cardiorespiratory System - Anatomy & Physiology
|linktext =Cardiorespiratory System
|maplink = Cardiorespiratory System (Content Map) - Anatomy & Physiology
|pagetype =Anatomy
}}
 

==Introduction==

The avian respiratory system contains some fundamental differences to the mammalian system.

==Avian Nasopharynx and Oropharynx==

*The nostrils of the bird, which lead into the [[Nasal cavity - Anatomy & Physiology|nasal cavity]], may have a flap of horn to protect them, known as the ''Operculum''.
*The Oral Cavity and the Nasal Cavity of the bird are interconnecting via a slit in the [[Hard Palate - Anatomy & Physiology|hard palate]] called the ''Choana''. Birds lack a [[Soft Palate - Anatomy & Physiology|soft palate]].
[[Image:Avianheadsaggitalsection.jpg|right|thumb|350px|©Nottingham 2008 ''Saggital Section of an Avian skull showing the conchae.]]
*There are Rostral, Middle and Caudal Conchae arising from the lateral wall, filling part of the [[Nasal cavity - Anatomy & Physiology|nasal cavity]].
**Rostral Conchae - Vestibular Region - lined with Stratified Squamous Epithelium
**Middle Conchae - Respiratory Region - lined with [[Respiratory Epithelium - Anatomy & Physiology|Respiratory Epithelium]].
**Caudal Conchae - [[Special Senses - Olfactory - Anatomy & Physiology|Olfactory]] Region - lined with [[Special Senses - Olfactory - Anatomy & Physiology|olfactory]] epithelium.
*The '''Infraorbital Sinus''' is a triangular cavity under the skin, rostroventral to the eye.
*Some marine birds have a ''Salt Gland'' (nasal gland) which excretes sodium.

==Avian Larynx==
*The [[Larynx - Anatomy & Physiology|larynx]] is on the floor of the [[Oral Cavity - Oropharynx - Anatomy & Physiology|oropharynx]] supported by '''Cricoid''' and paired '''Arytenoid''' Cartilages which are different in structure to those in mammals.
*There is no [[Epiglottis|Epiglottis.]]
*There are no vocal folds - birds vocalise using a [[Syrinx - Anatomy & Physiology|syrinx]].

==Avian Trachea==
*The avian [[Trachea - Anatomy & Physiology|trachea]] is composed of tightly stacked [[Bones and Cartilage - Anatomy & Physiology|cartilages]] which are shaped similarly to signet rings. These are complete with no dorsal space as in the mammalian [[Trachea - Anatomy & Physiology|trachea]]. They overlap considerably.
*The trachea can be palpated on the right side of the neck; it runs alongside the [[Oesophagus - Anatomy & Physiology|oesophagus]].
*The trachea is lined with [[Respiratory Epithelium - Anatomy & Physiology|Respiratory Epithelium]].
*The trachea bifurcates into two main [[Bronchi and bronchioles - Anatomy & Physiology|bronchi]] as in mammals. The [[Syrinx - Anatomy & Physiology|syrinx]] is formed by this terminal part of the trachea.

==Avian Lungs==
*Avian [[Lungs - Anatomy & Physiology|lungs]] are relatively compact, with a bird's lungs being approximately 50% as large as the lung of a mammal of a similar size. The lungs are unlobed and do not have the capacity to expand due to the fact that they contain cartilage.
*The lungs are positioned in the craniodorsal region of the body, and are deeply indented by both the thoracic [[Spinal Column - Anatomy & Physiology#Vertebrae and Joints|vertebrae]] and [[Ribs and Sternum - Anatomy & Physiology|ribs]].
*Birds do not have a [[Pleural cavity and membranes|pleural cavity]] as the lungs do not expand, thus the membranes are not necessary.
*One '''Primary Bronchi''' from the [[Trachea - Anatomy & Physiology|trachea]] enters each lung, narrowing as it travels through, and communicates with the '''Abdominal Air Sac'''. This bronchi gives off branches as it travels through the lung, known as '''Secondary Bronchi'''. Each of these gives off a further 400-500 '''Parabronchi''' in the walls of which, [[Gas Exchange - Anatomy & Physiology|gaseous exchange]] takes place.

==Air Sacs==
*Birds lack a [[Diaphragm - Anatomy & Physiology|diaphragm]], and their thoracic and abdominal cavities are continuous.
*The bird has a number of thin walled, easily distensible '''Air Sacs''' which can extend to approximatley 10x the volume of the [[Lungs - Anatomy & Physiology|lungs]]. These are present within body cavities, and extend into some specific [[Bones and Cartilage - Anatomy & Physiology|bones]], to take the place of [[Bone Marrow - Anatomy & Physiology|bone marrow]]. This has the added function of reducing the weight of the bone, as they are essentially filled with air.
*The air sacs create unidirectional flow of air to maximise oxygen extraction and reduce heat production during flight.
*The chicken has 8 air sacs:
**'''Cervical''' - this extends within the cervical and thoracic [[Spinal Column - Anatomy & Physiology#Vertebrae and Joints|vertebrae]].
**'''Clavicular''' - lies within the thoracic inlet, surrounding the [[Heart - Anatomy & Physiology|heart]], and within the humerus in the [[Forelimb - Anatomy & Physiology|forelimb]].
**'''Cranial Thoracic''' (x2) - these are ventral to the [[Lungs - Anatomy & Physiology|lungs]].
**'''Caudal Thoracic''' (x2) - located between the body wall and the thoracic air sacs.
**'''Abdominal''' (x2) - these are the largest air sacs and fill the caudodorsal region of the abdomen, in contact with [[Small Intestine - Anatomy & Physiology|small]] and [[Large Intestine - Anatomy & Physiology|large intestines]], [[Kidney Basic Anatomy & Physiology|kidneys]] and [[Reproductive System - Anatomy & Physiology|reproductive]] organs. In addition these airsacs utilise space within the acetabulum and synsacrum.
*The Cervical, Clavicular and Cranial Thoracic air sacs form one functional group - '''Cranial''', with the Caudal Thoracic and Abdominal Air sacs forming another, '''Caudal''' functional group.
*The air sacs have a vital role in [[Ventilation - Anatomy & Physiology|ventilation]], but do not have the capacity for [[Gas Exchange - Anatomy & Physiology|gaseous exchange]].

==Avian Ventilation==
*[[Ventilation - Anatomy & Physiology|Ventilation]] in birds is strikingly different to that of mammals in that air flows through the lungs in the same direction during both [[Ventilation - Anatomy & Physiology#Inspiration|inspiration]] and [[Ventilation - Anatomy & Physiology#Expiration|expiration]]. In addition, both the intaking of air and the expelling of air are active processes, requiring [[Muscles - Anatomy & Physiology|muscle]] contraction.
*During Inspiration, the [[Ribs and Sternum - Anatomy & Physiology|ribs]] are drawn forwards and the [[Ribs and Sternum - Anatomy & Physiology|sternum]] lowered, the Caudal air sacs receiving fresh air.
*Simultaneously, the Cranial air sacs receive air which was inhaled at the previous inhalation which is drawn from the lungs, this air has lost much of it's oxygen content.
*During Expiration, the [[Ribs and Sternum - Anatomy & Physiology|sternum]] is drawn caudal and dorsal, the air sacs are compressed, air from the caudal air sac passes through the [[Lungs - Anatomy & Physiology|lungs]], while the air in the cranial air sac leaves via the [[Trachea - Anatomy & Physiology|trachea]].
*Thus oxygenated air passes through the lungs on both [[Ventilation - Anatomy & Physiology#Inspiration|inspiration]] and [[Ventilation - Anatomy & Physiology#Expiration|expiration]].

==Avian Gas Exchange==
*Avian Gas exchange takes place not in alveoli, as in mammals, but within '''Air Capillaries''' which are extensions of the parabronchial lumen. They are an interconnecting network of loops, and closely intertwine with Blood Capillaries.
*The Air Capillaries and Blood Capillaries are arranged so that flow is ''crosscurrent''. This makes the [[Gas Exchange - Anatomy & Physiology|gaseous exchange]] which occurs from one to the other extremely efficient.

==Links==

==References==

*{{citation|initiallast = Dyce|initialfirst = K.M|2last = Sack|2first = W.O|finallast = Wensing|finalfirst = C.J.G|year = 2002|title = Textbook of Veterinary Anatomy|ed =3rd|city = Philadelphia|pub = Saunders}}
*{{citation|initiallast = Sjaastad|initialfirst = O.V|2last = Hove|2first = K|finallast = Sand|finalfirst = O|year = 2004|title = Physiology of Domestic Animals|city = Oslo|pub = Scandinavian Veterinary Press}}

Pleural Cavity and Membranes - Anatomy & Physiology

2008-09-09T12:59:47Z

Lwyacem:

Pleural Cavity and Membranes - Anatomy & Physiology

2008-09-09T12:57:50Z

Lwyacem: /* Introduction */

Gas Exchange - Anatomy & Physiology

2008-09-09T12:14:37Z

Lwyacem:

Gas Exchange - Anatomy & Physiology

2008-09-09T12:10:47Z

Lwyacem:

Gas Exchange - Anatomy & Physiology

2008-09-09T12:02:43Z

Lwyacem:

Gas Exchange - Anatomy & Physiology

2008-09-09T11:17:30Z

Lwyacem:

Gas Exchange - Anatomy & Physiology

2008-09-09T11:14:15Z

Lwyacem:

Lungs - Anatomy & Physiology

2008-09-09T11:11:12Z

Lwyacem:

{{toplink
|backcolour = D1EEEE
|linkpage =Cardiorespiratory System - Anatomy & Physiology
|linktext =Cardiorespiratory System
|maplink = Cardiorespiratory System (Content Map) - Anatomy & Physiology
|pagetype =Anatomy
}}
 

==Introduction==
[[Image:Doglungdeflated.jpg|right|thumb|200px|©RVC 2008]]
[[Image:Doglunginflated.jpg|right|thumb|200px|©RVC 2008]]
[[Image:Routeofairthroughrespiratorysystem.jpg|right|thumb|200px|'''Schematic Diagram showing the route air takes through the respiratory system''']]
The lungs are the site for [[Gas Exchange - Anatomy & Physiology|gaseous exchange]], and are situated within the thoracic cavity. They occupy approximately 5% of the body volume in mammals when relaxed, and their elastic nature allows them to expand and contract with the processes of [[Ventilation - Anatomy & Physiology#Inspiration|inspiration]] and [[Ventilation - Anatomy & Physiology#Expiration|expiration]].

The lungs, along with the [[Larynx - Anatomy & Physiology|larynx]] and [[Trachea - Anatomy & Physiology|trachea]], develop from a ventral respiratory tract. After separation from the developing [[Oesophagus - Anatomy & Physiology|oesophagus]], two lung buds develop, which undergo divisions as they grow, forming the beginnings of the [[Bronchi and bronchioles - Anatomy & Physiology|bronchial]] tree. This process is not completed at the time of [[Parturition - Normal Parturition - Anatomy & Physiology|parturition]].

==Structure==

*The left and right lungs lie within their [[Pleural cavity and membranes - Anatomy & Physiology|pleural]] sac and are only attached by their roots, to the [[Mediastinum - Anatomy & Physiology|mediastinum]], so they are fairly free within the thoracic cavity.
*The right lung is always larger than the left, due to the positioning of the [[Heart - Anatomy & Physiology|heart]]. The apex of the lungs is their cranial point.
*In most species the lungs are divided into lobes by the [[Bronchi and bronchioles - Anatomy & Physiology|bronchial]] tree:
**'''Left Lung''' = Cranial and Caudal lobes.
**'''Right Lung''' = Cranial, Caudal, Middle and Accessory lobes. The cranial lobe is further divided by an external fissure.
*The bulk of the lung consists of [[Bronchi and bronchioles - Anatomy & Physiology|bronchi]], [[Anatomy of Blood Vessels - Anatomy & Physiology|blood vessels]] and connective tissue. The terminal [[Bronchi and bronchioles - Anatomy & Physiology|bronchioles]] have alveoli scattered along their length, and are continued by alveolar ducts, alveolar sacs and finally alveoli.
**'''Alveolar Ducts''': These have alveoli which open on all of it's sides, they have no 'walls' as such. Openings to individual alveoli are guarded by [[Muscles - Anatomy & Physiology#Smooth Muscle|smooth muscle]].
**'''Alveolar Sacs''': These are rotunda-like areas on the end of each alveolar ducts which are usually present in clusters.
**'''Alveoli''': These are minute, polygonal chambers, whose diameter changes with the processes of [[Ventilation - Anatomy & Physiology#Inspiration|inspiration]] and [[Ventilation - Anatomy & Physiology#Expiration|expiration]], and varies by species. The wall of the alveoli is extremely thin, consisting of 2 irregular layers of epithelial sheets, 'sandwiching' a network of capillaries. Thus the ''Blood-Gas Barrier'' is just a single basal lamina - ideal for [[Gas Exchange - Anatomy & Physiology|gaseous exchange]]. The alveolar interstitium is formed from connective tissue fibres and cells, which include collagen fibrils and elastin fibres.

==Function==

*[[Gas Exchange - Anatomy & Physiology|Gas Exchange]]

==Vasculature==

*The '''Pulmonary Arteries''' follow the bronchi while the '''Pulmonary veins''' sometimes run separately.
*'''Bronchial arteries''' from the Aorta supply the bronchi, and '''Bronchial veins''' may drain this blood to the [[Structure of the Heart - Anatomy & Physiology#Right Atrium|right atrium]] via the '''Azygous Vein'''. More often the blood from the bronchi drains directly to the [[Structure of the Heart - Anatomy & Physiology#Left Atrium|left atrium]].

==Innervation==

* Nervous supply to the lung is via the '''Pulmonary Plexus''' within the [[Mediastinum - Anatomy & Physiology|mediastinum]].
*The Pulmonary Plexus consists of Sympathetic Fibres largely from the Stellate Ganglion, and Parasympathetic Fibres from the [[Nervous System - CNS - Anatomy & Physiology#Innervation - Cranial Nerves|Vagus nerve]].

==Lymphatics==

* Lymph drains to the '''Tracheobronchial''' and '''Mediastinal''' [[Lymph Nodes - Anatomy & Physiology|lymph nodes]].

==Histology==

<center><gallery>
Image:Lungadultlowmag.jpg|'''Lung (adult)'''©RVC 2008
Image:SEMAdultSheepLung.jpg|'''SEM of Adult Sheep Lung'''©RVC 2008
Image:Bronchuslowpower.jpg|'''Bronchus'''©RVC 2008
Image:Bronchuslowpower2.jpg|'''Bronchus'''©RVC 2008
Image:Alveoli.jpg|'''Alveoli'''©RVC 2008
Image:Alveoli2.jpg|'''Alveoli'''©RVC 2008
</gallery></center>

==Species Differences==

* The lungs of the '''Horse''' show almost no lobation, and the right lung of the horse lacks a Middle Lobe.
*The lungs of '''Ruminants''' and '''Pigs''' are obviously lobed.
*The fissures between lobes (''Interlobar fissures'') are deeper in the dog and cat lung compared to other species.
*[[Avian Respiration - Anatomy & Physiology|Avian Respiration]] has many fundamental differences to mammalian respiration.
*The [[Respiration in Non-Homeotherms - Anatomy & Physiology|Respiratory Systems of non-Homeotherms]] are also very different to that of mammals.

==Links==

[[Lungs - Pathology]]

==References==

*{{citation|initiallast = Dyce|initialfirst = K.M|2last = Sack|2first = W.O|finallast = Wensing|finalfirst = C.J.G|year = 2002|title = Textbook of Veterinary Anatomy|ed =3rd|city = Philadelphia|pub = Saunders}}

Bronchi and Bronchioles - Anatomy & Physiology

2008-09-09T11:07:34Z

Lwyacem:

Cardiorespiratory System Overview - Anatomy & Physiology

2008-09-09T11:03:02Z

Lwyacem:

{{toplink
|linkpage =Anatomy and Physiology
|linktext =ANATOMY & PHYSIOLOGY
|thispagenormal = Cardiorespiratory System - Anatomy & Physiology
|thispagemap = Cardiorespiratory System (Content Map) - Anatomy & Physiology
|pagetype =Anatomy
}}
 

==Introduction==
[[Image:Routeofairthroughrespiratorysystem.jpg|right|thumb|200px|'''Schematic Diagram showing the route air takes through the respiratory system''']]

The mammalian cardiovascular and respiratory systems have evolved primarily to provide the tissues of the body with oxygen and to remove carbon dioxide. The cardiorespiratory system also has metabolic and heat exchange roles.

===Respiratory System===

Air is [[Ventilation - Anatomy & Physiology|inhaled]] and passes through the upper respiratory tract (nares, [[Nasal cavity - Anatomy & Physiology|nasal cavity]], [[Nasopharynx - Anatomy & Physiology|nasopharynx]], [[Larynx - Anatomy & Physiology|larynx]], [[Trachea - Anatomy & Physiology|trachea]]) where it is heated and moistened. It then passes to the lower respiratory tract ([[Bronchi and bronchioles - Anatomy & Physiology|bronchi, bronchioles]], [[Lungs - Anatomy & Physiology|alveoli]]) where oxygen diffuses across the alveolar wall and into the blood, forming oxyhaemoglobin.

===Cardiovascular System===

Blood, which has been oxygenated by the [[Lungs - Anatomy & Physiology|lungs]], flows through the pulmonary vein to the left atrium of the heart and subsequently to the left ventricle from which it is ejected by the heart during ventricular systole. Oxygenated blood is then distributed to the different parts of the body via the aorta. The distribution of blood is controlled by vascular tone which dictates the degree of perfusion of capillary beds and therefore the amount of oxygen available to the various tissues. Carbon dioxide produced from cellular respiration is removed from the tissues and transported either attached to proteins, in solution or as bicarbonate via the venous system to the vena cavae and ultimately to the right atrium. The passage of venous blood is a product of blood flow, vascular valves and muscular and respiratory function. Carbon dioxide rich blood enters the right ventricle and is then pumped to the lungs via the pulmonary artery.

===Integration===

The function of the cardiac and respiratory systems are tightly linked and regulated to maintain blood pressure, tissue oxygen delivery and carbon dioxide removal. Cardiac function is controlled by baroreceptors (pressure receptors) which result in changes to the heartrate, contractility and vascular tone. Respiratory function is controlled centrally by chemoreceptors to maintain rate and both centrally and locally to maintain bronchiolar tone.

==Upper Respiratory Tract==

[[Nasal cavity - Anatomy & Physiology|Nasal Cavity]]

[[Paranasal sinuses - Anatomy & Physiology|Paranasal Sinuses]]

[[Pharynx - Anatomy & Physiology|Pharynx]]

[[Guttural pouches - Anatomy & Physiology|Guttural Pouches]]

[[Larynx - Anatomy & Physiology|Larynx]]

[[Trachea - Anatomy & Physiology|Trachea]]

==Lower Respiratory Tract==

[[Bronchi and bronchioles - Anatomy & Physiology|Bronchi & Bronchioles]]

[[Lungs - Anatomy & Physiology|Anatomy of the Lungs]]

[[Ventilation - Anatomy & Physiology|Ventilation]]

[[Gas Exchange - Anatomy & Physiology|Gas Exchange]]

[[Pleural cavity and membranes - Anatomy & Physiology|Pleural Cavity & Membranes]]

==Cardiovascular System==

[[Heart - Anatomy & Physiology|Heart]]

[[Vascular System - Anatomy & Physiology|Vascular System]]

==Acknowledgements and Reference Material==

[[References for the Cardiorespiratory system - Anatomy & Physiology| References]]

Respiration in Non-Homeotherms - Anatomy & Physiology

2008-08-15T11:33:18Z

Lwyacem:

{{toplink
|backcolour = D1EEEE
|linkpage =Cardiorespiratory System - Anatomy & Physiology
|linktext =Cardiorespiratory System
|maplink = Cardiorespiratory (Content Map) - Anatomy & Physiology
|pagetype =Anatomy
}}
 

==Introduction==
==Fish==

Fish live in a relatively dense and viscous fluid, which has little oxygen carrying capacity. In order to gain sufficient [[Gas Exchange - Anatomy & Physiology|gaseous exchange]] for survival, fish have developed a highly efficient system which has a large surface area, and utilises energy - the gills.

===Gills===

Gills are in the walls of both sides of the [[Pharynx - Anatomy & Physiology|pharynx]] and are composed of filaments which increase the surface area.
When a fish breaths, it takes in water into the mouth, which is then forced out through the gills.

A '''Countercurrent Exchange''' system is in place within the gills to make gaseous exchange more efficient.

==Amphibia==

In amphibian species, the [[Skin - Anatomy & Physiology|skin]] forms the major, and sometimes only respiratory organ.

The [[Skin - Anatomy & Physiology|skin]] of amphibia is:
*Thin
*Poorly keratinised
*Highly vascularised
*Moist to promote diffusion of gases

'''Aquatic''' amphibians may also have ''internal gills'' and '''Pharyngeal Slits'''.

Most Amphibia also have lungs for breathing. This contains interconnecting septa which divide the lumen into '''Faveoli''', compartments which open into a central chamber within each [[Lungs - Anatomy & Physiology|lung]].

==Reptiles==

Reptiles have a fundamentally different respiratory system to that of mammals, in that they lack a bronchial tree.

Route of Air in the Reptiliant Respiratory System:
#Air enters via nares
#[[Nasal Cavity - Anatomy & Physiology|Nasal Cavity]]
#Choana
#Glottis (base of tongue)
#Trachea
#Bronchi
#Lungs

The lungs are paired, with respiration only occuring in the cranial region.

The Respiratory surface is composed of '''Faveoli''', honeycomb shaped structures which line the walls.

===Lizards===
*No diaphragm
*Simple, saclike, paired [[Lungs - Anatomy & Physiology|lungs]].
*Cranial part of lung is site of respiratory function
*Caudal part of lung forms air ''reservoir''
*Ventilation occurs via expansion and contraction of the ribs

===Snakes===
*Larynx projects medially from the floor of the mouth and is fused with the first few cartilage rings of the trachea. This forms a rigid '''Glottis'''.
*Tongue is fixed at the rostral point of the oral cavity.
*Generally only the right lung is present. The lung of snakes is very fragile.
*Inspiration is an active process, made possible by expansion of the ribs. It occurs approx once every 30seconds in large, healthy snakes. Expiration is a passive prcoess.

===Chelonians===
*Have paired lungs in the '''Dorsal Cavity'''. Intestines etc lie in the '''Ventral Cavity'''. These are separated by a diaphragmatic septum which has no muscular part.
*Lungs are ventilated by leg movement in terrestrial animals.

Respiration in Non-Homeotherms - Anatomy & Physiology

2008-08-15T11:24:18Z

Lwyacem: /* Lizards */

{{toplink
|backcolour = D1EEEE
|linkpage =Cardiorespiratory System - Anatomy & Physiology
|linktext =Cardiorespiratory System
|maplink = Cardiorespiratory (Content Map) - Anatomy & Physiology
|pagetype =Anatomy
}}
 

==Introduction==
==Fish==

Fish live in a relatively dense and viscous fluid, which has little oxygen carrying capacity. In order to gain sufficient gaseous exchange for survival, fish have developed a highly efficient system which has a large surface area, and utilises energy - the gills.

===Gills===

Gills are in the walls of both sides of the pharynx and are composed of filaments which increase the surface area.
When a fish breaths, it takes in water into the mouth, which is then forced out through the gills.

A '''Countercurrent Exchange''' system is in place within the gills to make gaseous exchange more efficient.

==Amphibia==

In amphibian species, the [[Skin - Anatomy & Physiology|skin]] forms the major, and sometimes only respiratory organ.

The [[Skin - Anatomy & Physiology|skin]] of amphibia is:
*Thin
*Poorly keratinised
*Highly vascularised
*Moist to promote diffusion of gases

'''Aquatic''' amphibians may also have ''internal gills'' and '''Pharyngeal Slits'''.

Most Amphibia also have lungs for breathing. This contains interconnecting septa which divide the lumen into '''Faveoli''', compartments which open into a central chamber within each lung.

==Reptiles==

Reptiles have a fundamentally different respiratory system to that of mammals, in that they lack a bronchial tree.

Route of Air in the Reptiliant Respiratory System:
#Air enters via nares
#[[Nasal Cavity - Anatomy & Physiology|Nasal Cavity]]
#Choana
#Glottis (base of tongue)
#Trachea
#Bronchi
#Lungs

The lungs are paired, with respiration only occuring in the cranial region.

The Respiratory surface is composed of '''Faveoli''', honeycomb shaped structures which line the walls.

===Lizards===
*No diaphragm
*Simple, saclike, paired [[Lungs - Anatomy & Physiology|lungs]].
*Cranial part of lung is site of respiratory function
*Caudal part of lung forms air ''reservoir''
*Ventilation occurs via expansion and contraction of the ribs

===Snakes===
*Larynx projects medially from the floor of the mouth and is fused with the first few cartilage rings of the trachea. This forms a rigid '''Glottis'''.
*Tongue is fixed at the rostral point of the oral cavity.
*Generally only the right lung is present. The lung of snakes is very fragile.
*Inspiration is an active process, made possible by expansion of the ribs. It occurs approx once every 30seconds in large, healthy snakes. Expiration is a passive prcoess.

===Chelonians===
*Have paired lungs in the '''Dorsal Cavity'''. Intestines etc lie in the '''Ventral Cavity'''. These are separated by a diaphragmatic septum which has no muscular part.
*Lungs are ventilated by leg movement in terrestrial animals.

Respiration in Non-Homeotherms - Anatomy & Physiology

2008-08-15T11:13:45Z

Lwyacem: /* Reptiles */

{{toplink
|backcolour = D1EEEE
|linkpage =Cardiorespiratory System - Anatomy & Physiology
|linktext =Cardiorespiratory System
|maplink = Cardiorespiratory (Content Map) - Anatomy & Physiology
|pagetype =Anatomy
}}
 

==Introduction==
==Fish==

Fish live in a relatively dense and viscous fluid, which has little oxygen carrying capacity. In order to gain sufficient gaseous exchange for survival, fish have developed a highly efficient system which has a large surface area, and utilises energy - the gills.

===Gills===

Gills are in the walls of both sides of the pharynx and are composed of filaments which increase the surface area.
When a fish breaths, it takes in water into the mouth, which is then forced out through the gills.

A '''Countercurrent Exchange''' system is in place within the gills to make gaseous exchange more efficient.

==Amphibia==

In amphibian species, the [[Skin - Anatomy & Physiology|skin]] forms the major, and sometimes only respiratory organ.

The [[Skin - Anatomy & Physiology|skin]] of amphibia is:
*Thin
*Poorly keratinised
*Highly vascularised
*Moist to promote diffusion of gases

'''Aquatic''' amphibians may also have ''internal gills'' and '''Pharyngeal Slits'''.

Most Amphibia also have lungs for breathing. This contains interconnecting septa which divide the lumen into '''Faveoli''', compartments which open into a central chamber within each lung.

==Reptiles==

Reptiles have a fundamentally different respiratory system to that of mammals, in that they lack a bronchial tree.

Route of Air in the Reptiliant Respiratory System:
#Air enters via nares
#[[Nasal Cavity - Anatomy & Physiology|Nasal Cavity]]
#Choana
#Glottis (base of tongue)
#Trachea
#Bronchi
#Lungs

The lungs are paired, with respiration only occuring in the cranial region.

The Respiratory surface is composed of '''Faveoli''', honeycomb shaped structures which line the walls.

===Lizards===
*No diaphragm
*Simple, saclike, paired lungs
*Cranial part of lung is site of respiratory function
*Caudal part of lung forms air ''reservoir''
*Ventilation occurs via expansion and contraction of the ribs

===Snakes===
*Larynx projects medially from the floor of the mouth and is fused with the first few cartilage rings of the trachea. This forms a rigid '''Glottis'''.
*Tongue is fixed at the rostral point of the oral cavity.
*Generally only the right lung is present. The lung of snakes is very fragile.
*Inspiration is an active process, made possible by expansion of the ribs. It occurs approx once every 30seconds in large, healthy snakes. Expiration is a passive prcoess.

===Chelonians===
*Have paired lungs in the '''Dorsal Cavity'''. Intestines etc lie in the '''Ventral Cavity'''. These are separated by a diaphragmatic septum which has no muscular part.
*Lungs are ventilated by leg movement in terrestrial animals.

Respiration in Non-Homeotherms - Anatomy & Physiology

2008-08-15T11:05:40Z

Lwyacem: /* Amphibia */

{{toplink
|backcolour = D1EEEE
|linkpage =Cardiorespiratory System - Anatomy & Physiology
|linktext =Cardiorespiratory System
|maplink = Cardiorespiratory (Content Map) - Anatomy & Physiology
|pagetype =Anatomy
}}
 

==Introduction==
==Fish==

Fish live in a relatively dense and viscous fluid, which has little oxygen carrying capacity. In order to gain sufficient gaseous exchange for survival, fish have developed a highly efficient system which has a large surface area, and utilises energy - the gills.

===Gills===

Gills are in the walls of both sides of the pharynx and are composed of filaments which increase the surface area.
When a fish breaths, it takes in water into the mouth, which is then forced out through the gills.

A '''Countercurrent Exchange''' system is in place within the gills to make gaseous exchange more efficient.

==Amphibia==

In amphibian species, the [[Skin - Anatomy & Physiology|skin]] forms the major, and sometimes only respiratory organ.

The [[Skin - Anatomy & Physiology|skin]] of amphibia is:
*Thin
*Poorly keratinised
*Highly vascularised
*Moist to promote diffusion of gases

'''Aquatic''' amphibians may also have ''internal gills'' and '''Pharyngeal Slits'''.

Most Amphibia also have lungs for breathing. This contains interconnecting septa which divide the lumen into '''Faveoli''', compartments which open into a central chamber within each lung.

==Reptiles==

Reptiles have a fundamentally different respiratory system to that of mammals, in that they lack a bronchial tree.

Route of Air in the Reptiliant Respiratory System:
#Air enters via nares
#Nasal Cavity
#Choana
#Glottis (base of tongue)
#Trachea
#Bronchi
#Lungs

The lungs are paired, with respiration only occuring in the cranial region.

The Respiratory surface is composed of '''Faveoli''', honeycomb shaped structures which line the walls.

===Lizards===
*No diaphragm
*Simple, saclike, paired lungs
*Cranial part of lung is site of respiratory function
*Caudal part of lung forms air ''reservoir''
*Ventilation occurs via expansion and contraction of the ribs

===Snakes===
*Larynx projects medially from the floor of the mouth and is fused with the first few cartilage rings of the trachea. This forms a rigid '''Glottis'''.
*Tongue is fixed at the rostral point of the oral cavity.
*Generally only the right lung is present. The lung of snakes is very fragile.
*Inspiration is an active process, made possible by expansion of the ribs. It occurs approx once every 30seconds in large, healthy snakes. Expiration is a passive prcoess.

===Chelonians===
*Have paired lungs in the '''Dorsal Cavity'''. Intestines etc lie in the '''Ventral Cavity'''. These are separated by a diaphragmatic septum which has no muscular part.
*Lungs are ventilated by leg movement in terrestrial animals.

Respiration in Non-Homeotherms - Anatomy & Physiology

2008-08-15T10:49:40Z

Lwyacem: /* Fish */

{{toplink
|backcolour = D1EEEE
|linkpage =Cardiorespiratory System - Anatomy & Physiology
|linktext =Cardiorespiratory System
|maplink = Cardiorespiratory (Content Map) - Anatomy & Physiology
|pagetype =Anatomy
}}
 

==Introduction==
==Fish==

Fish live in a relatively dense and viscous fluid, which has little oxygen carrying capacity. In order to gain sufficient gaseous exchange for survival, fish have developed a highly efficient system which has a large surface area, and utilises energy - the gills.

===Gills===

Gills are in the walls of both sides of the pharynx and are composed of filaments which increase the surface area.
When a fish breaths, it takes in water into the mouth, which is then forced out through the gills.

A '''Countercurrent Exchange''' system is in place within the gills to make gaseous exchange more efficient.

==Amphibia==

In amphibian species, the [[Skin - Anatomy & Physiology|skin]] forms the major, and sometimes only respiratory organ.

The skin of amphibia is:
*Thin
*Poorly keratinised
*Highly vascularised
*Moist to promote diffusion of gases

'''Aquatic''' amphibians may also have ''internal gills'' and '''Pharyngeal Slits'''.

Most Amphibia also have lungs for breathing. This contains interconnecting septa which divide the lumen into '''Faveoli''', compartments which open into a central chamber within each lung.

==Reptiles==

Reptiles have a fundamentally different respiratory system to that of mammals, in that they lack a bronchial tree.

Route of Air in the Reptiliant Respiratory System:
#Air enters via nares
#Nasal Cavity
#Choana
#Glottis (base of tongue)
#Trachea
#Bronchi
#Lungs

The lungs are paired, with respiration only occuring in the cranial region.

The Respiratory surface is composed of '''Faveoli''', honeycomb shaped structures which line the walls.

===Lizards===
*No diaphragm
*Simple, saclike, paired lungs
*Cranial part of lung is site of respiratory function
*Caudal part of lung forms air ''reservoir''
*Ventilation occurs via expansion and contraction of the ribs

===Snakes===
*Larynx projects medially from the floor of the mouth and is fused with the first few cartilage rings of the trachea. This forms a rigid '''Glottis'''.
*Tongue is fixed at the rostral point of the oral cavity.
*Generally only the right lung is present. The lung of snakes is very fragile.
*Inspiration is an active process, made possible by expansion of the ribs. It occurs approx once every 30seconds in large, healthy snakes. Expiration is a passive prcoess.

===Chelonians===
*Have paired lungs in the '''Dorsal Cavity'''. Intestines etc lie in the '''Ventral Cavity'''. These are separated by a diaphragmatic septum which has no muscular part.
*Lungs are ventilated by leg movement in terrestrial animals.

Respiration in Non-Homeotherms - Anatomy & Physiology

2008-08-15T10:33:46Z

Lwyacem: /* Snake */

{{toplink
|backcolour = D1EEEE
|linkpage =Cardiorespiratory System - Anatomy & Physiology
|linktext =Cardiorespiratory System
|maplink = Cardiorespiratory (Content Map) - Anatomy & Physiology
|pagetype =Anatomy
}}
 

==Introduction==
==Fish==

Fish live in a relatively dense and viscous fluid, which has little oxygen carrying capacity. In order to gain sufficient gaseous exchange for survival, fish have developed a highly efficient system which has a large surface area, and utilises energy - the gills.

===Gills===

==Amphibia==

In amphibian species, the [[Skin - Anatomy & Physiology|skin]] forms the major, and sometimes only respiratory organ.

The skin of amphibia is:
*Thin
*Poorly keratinised
*Highly vascularised
*Moist to promote diffusion of gases

'''Aquatic''' amphibians may also have ''internal gills'' and '''Pharyngeal Slits'''.

Most Amphibia also have lungs for breathing. This contains interconnecting septa which divide the lumen into '''Faveoli''', compartments which open into a central chamber within each lung.

==Reptiles==

Reptiles have a fundamentally different respiratory system to that of mammals, in that they lack a bronchial tree.

Route of Air in the Reptiliant Respiratory System:
#Air enters via nares
#Nasal Cavity
#Choana
#Glottis (base of tongue)
#Trachea
#Bronchi
#Lungs

The lungs are paired, with respiration only occuring in the cranial region.

The Respiratory surface is composed of '''Faveoli''', honeycomb shaped structures which line the walls.

===Lizards===
*No diaphragm
*Simple, saclike, paired lungs
*Cranial part of lung is site of respiratory function
*Caudal part of lung forms air ''reservoir''
*Ventilation occurs via expansion and contraction of the ribs

===Snakes===
*Larynx projects medially from the floor of the mouth and is fused with the first few cartilage rings of the trachea. This forms a rigid '''Glottis'''.
*Tongue is fixed at the rostral point of the oral cavity.
*Generally only the right lung is present. The lung of snakes is very fragile.
*Inspiration is an active process, made possible by expansion of the ribs. It occurs approx once every 30seconds in large, healthy snakes. Expiration is a passive prcoess.

===Chelonians===
*Have paired lungs in the '''Dorsal Cavity'''. Intestines etc lie in the '''Ventral Cavity'''. These are separated by a diaphragmatic septum which has no muscular part.
*Lungs are ventilated by leg movement in terrestrial animals.

Respiration in Non-Homeotherms - Anatomy & Physiology

2008-08-15T10:33:17Z

Lwyacem: /* Lizards */

{{toplink
|backcolour = D1EEEE
|linkpage =Cardiorespiratory System - Anatomy & Physiology
|linktext =Cardiorespiratory System
|maplink = Cardiorespiratory (Content Map) - Anatomy & Physiology
|pagetype =Anatomy
}}
 

==Introduction==
==Fish==

Fish live in a relatively dense and viscous fluid, which has little oxygen carrying capacity. In order to gain sufficient gaseous exchange for survival, fish have developed a highly efficient system which has a large surface area, and utilises energy - the gills.

===Gills===

==Amphibia==

In amphibian species, the [[Skin - Anatomy & Physiology|skin]] forms the major, and sometimes only respiratory organ.

The skin of amphibia is:
*Thin
*Poorly keratinised
*Highly vascularised
*Moist to promote diffusion of gases

'''Aquatic''' amphibians may also have ''internal gills'' and '''Pharyngeal Slits'''.

Most Amphibia also have lungs for breathing. This contains interconnecting septa which divide the lumen into '''Faveoli''', compartments which open into a central chamber within each lung.

==Reptiles==

Reptiles have a fundamentally different respiratory system to that of mammals, in that they lack a bronchial tree.

Route of Air in the Reptiliant Respiratory System:
#Air enters via nares
#Nasal Cavity
#Choana
#Glottis (base of tongue)
#Trachea
#Bronchi
#Lungs

The lungs are paired, with respiration only occuring in the cranial region.

The Respiratory surface is composed of '''Faveoli''', honeycomb shaped structures which line the walls.

===Lizards===
*No diaphragm
*Simple, saclike, paired lungs
*Cranial part of lung is site of respiratory function
*Caudal part of lung forms air ''reservoir''
*Ventilation occurs via expansion and contraction of the ribs

===Snake===
*Larynx projects medially from the floor of the mouth and is fused with the first few cartilage rings of the trachea. This forms a rigid '''Glottis'''.
*Tongue is fixed at the rostral point of the oral cavity.
*Generally only the right lung is present. The lung of snakes is very fragile.
*Inspiration is an active process, made possible by expansion of the ribs. It occurs approx once every 30seconds in large, healthy snakes. Expiration is a passive prcoess.

===Chelonians===
*Have paired lungs in the '''Dorsal Cavity'''. Intestines etc lie in the '''Ventral Cavity'''. These are separated by a diaphragmatic septum which has no muscular part.
*Lungs are ventilated by leg movement in terrestrial animals.

Respiration in Non-Homeotherms - Anatomy & Physiology

2008-08-15T10:24:01Z

Lwyacem: /* Reptiles */

{{toplink
|backcolour = D1EEEE
|linkpage =Cardiorespiratory System - Anatomy & Physiology
|linktext =Cardiorespiratory System
|maplink = Cardiorespiratory (Content Map) - Anatomy & Physiology
|pagetype =Anatomy
}}
 

==Introduction==
==Fish==

Fish live in a relatively dense and viscous fluid, which has little oxygen carrying capacity. In order to gain sufficient gaseous exchange for survival, fish have developed a highly efficient system which has a large surface area, and utilises energy - the gills.

===Gills===

==Amphibia==

In amphibian species, the [[Skin - Anatomy & Physiology|skin]] forms the major, and sometimes only respiratory organ.

The skin of amphibia is:
*Thin
*Poorly keratinised
*Highly vascularised
*Moist to promote diffusion of gases

'''Aquatic''' amphibians may also have ''internal gills'' and '''Pharyngeal Slits'''.

Most Amphibia also have lungs for breathing. This contains interconnecting septa which divide the lumen into '''Faveoli''', compartments which open into a central chamber within each lung.

==Reptiles==

Reptiles have a fundamentally different respiratory system to that of mammals, in that they lack a bronchial tree.

Route of Air in the Reptiliant Respiratory System:
#Air enters via nares
#Nasal Cavity
#Choana
#Glottis (base of tongue)
#Trachea
#Bronchi
#Lungs

The lungs are paired, with respiration only occuring in the cranial region.

The Respiratory surface is composed of '''Faveoli''', honeycomb shaped structures which line the walls.

===Lizards===
*No diaphragm

Respiration in Non-Homeotherms - Anatomy & Physiology

2008-08-15T10:15:04Z

Lwyacem:

{{toplink
|backcolour = D1EEEE
|linkpage =Cardiorespiratory System - Anatomy & Physiology
|linktext =Cardiorespiratory System
|maplink = Cardiorespiratory (Content Map) - Anatomy & Physiology
|pagetype =Anatomy
}}
 

==Introduction==
==Fish==

Fish live in a relatively dense and viscous fluid, which has little oxygen carrying capacity. In order to gain sufficient gaseous exchange for survival, fish have developed a highly efficient system which has a large surface area, and utilises energy - the gills.

===Gills===

==Amphibia==

In amphibian species, the [[Skin - Anatomy & Physiology|skin]] forms the major, and sometimes only respiratory organ.

The skin of amphibia is:
*Thin
*Poorly keratinised
*Highly vascularised
*Moist to promote diffusion of gases

'''Aquatic''' amphibians may also have ''internal gills'' and '''Pharyngeal Slits'''.

Most Amphibia also have lungs for breathing. This contains interconnecting septa which divide the lumen into '''Faveoli''', compartments which open into a central chamber within each lung.

==Reptiles==

Reptiles have a fundamentally different respiratory system to that of mammals.

Respiration in Non-Homeotherms - Anatomy & Physiology

2008-08-15T10:03:54Z

Lwyacem:

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|pagetype =Anatomy
}}
 

==Introduction==
==Fish==

Fish live in a relatively dense and viscous fluid, which has little oxygen carrying capacity. In order to gain sufficient gaseous exchange for survival, fish have developed a highly efficient system which has a large surface area, and utilises energy - the gills.

===Gills===

==Amphibia==

Respiration in Non-Homeotherms - Anatomy & Physiology

2008-08-15T09:38:54Z

Lwyacem: New page: {{toplink |backcolour = D1EEEE |linkpage =Cardiorespiratory System - Anatomy & Physiology |linktext =Cardiorespiratory System |maplink = Cardiorespiratory (Content Map) - Anatomy & Physiol...

Nasal Cavity - Anatomy & Physiology

2008-08-15T09:26:44Z

Lwyacem: /* Species Differences */

{{toplink
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|linkpage =Cardiorespiratory System - Anatomy & Physiology
|linktext =Cardiorespiratory System
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|pagetype =Anatomy
}}
 
[[Image:Nasal Cavities.jpg|thumb|right|300px|Nasal Cavities - Copyright David Bainbridge]]
==Introduction==

The respiratory tract begins with the ''nose'' which includes the external nose, internal nasal cavities and [[Paranasal sinuses - Anatomy & Physiology|paranasal sinuses]].
As well as being vital for transport of gases to the [[Cardiorespiratory System - Anatomy & Physiology#Lower Respiratory Tract|lower respiratory tract]], the nose is also the site for one of the special senses - [[Special Senses - Olfactory - Anatomy & Physiology|''Olfaction'']].

==Structure==

*The nose consists of the external nares with nasal [[Bones and Cartilage - Anatomy & Physiology#Structure and Function of Cartilage|cartilages]], the nasal cavity (including the nasal meatus and conchae), and the [[Paranasal sinuses - Anatomy & Physiology|paranasal sinuses]].

*The nasal cavity is essentially a tube with a wall established by several [[Skull and Facial Muscles - Anatomy & Physiology#Bones of the Skull|bones of the skull]]. The borders of the nasal cavity are as follows:

- ''Caudal'': cribrifrom plate of the [[Skull and Facial Muscles - Anatomy & Physiology#Ethmoid Bone (os ethmoidale)|ethmoid bone]]

- ''Ventral'': continuous with the nasopharynx

- ''Dorsal'': the maxilla and the palatine processes of the [[Skull and Facial Muscles - Anatomy & Physiology#Incisive Bone (os incisivium)|incisive bone]]

*Rostrally, the median septum is a continuation of the [[Skull and Facial Muscles - Anatomy & Physiology#Ethmoid Bone (os ethmoidale)|ethmoid bone]]. The median septum is made up of [[Bones and Cartilage - Anatomy & Physiology#Hyaline Cartilage|hyaline cartilage]], and divides the nasal cavity into left and right halves.

[[Image:DogHeadDissection.jpg|right|thumb|200px|The nasal cavity can be seen filled with conchae in this photograph of a canine head. ©Nottingham 2008]]

*The nasal cavity is occupied to a large extent by '''''Nasal conchae'''''. These are turbinate bones which project into the nasal cavity with the purpose of supporting the [[Special Senses - Olfactory - Anatomy & Physiology|olfactory]] mucus membranes and increasing the respiratory surface area, creating turbulence within the passing air. This helps to filtrate and warm or cool the air that passes through.

*The Conchae are [[Bones and Cartilage - Anatomy & Physiology#Types of Cartilage|cartilage]]nous or ossified scrolls which arise from the [[Skull and Facial Muscles - Anatomy & Physiology#Ethmoid Bone (os ethmoidale|''ethmoid bone'']]. They are covered with mucous membrane, under which is a layer of anastomosing blood vessels.
The nasal conchae are more complex in animals with a better sense of smell, as they increase the surface area of the [[Special Senses - Olfactory - Anatomy & Physiology|Olfactory]] region, further.

*There are dorsal and ventral conchae, the dorsal concha originating from the [[Skull and Facial Muscles - Anatomy & Physiology#Ethmoid Bone (os ethmoidale)|ethmoid bone]] and attaching to the maxilla, and the vental conchae originating from the [[Skull and Facial Muscles - Anatomy & Physiology#Maxilla|maxilla]] and extending further into the nasal cavity.

*The conchae divide the nasal cavity into nasal ducts or ''meatuses'', which branch out from a common nasal meatus which is adjacent to the nasal septum. There are three nasal meatuses which branch from the common nasal meatus: dorsal, middle and ventral:

- '''Dorsal nasal meatus''': the passage between the roof of the nasal cavity and the dorsal nasal concha

- '''Middle nasal meatus''': between the dorsal and ventral conchae, and communicates with the [[Paranasal sinuses - Anatomy & Physiology|paranasal sinuses]].

- '''Ventral nasal meatus''': the main pathway for airflow leading to the pharynx, and is positioned between the ventral nasal concha and the floor of the nasal cavity.

- '''Common nasal meatus''': the longitudinal space on either side of the nasal septum.

*The [[Paranasal sinuses - Anatomy & Physiology|Paranasal Sinuses]] are extensions of the nasal cavity.

==Function==

*In addition to [[Special Senses - Olfactory - Anatomy & Physiology|Olfaction,]] the function of the nasal cavity is to modify the incoming air before is is transported further down the respiratory tract.
*Air is warmed as it passes over the highly vascularised mucosal surfaces of the conchae, humidified by the evaporation from nasal secretion and cleaned as it contacts the secretion from mucus glands within the nasal cavity. The mucus secreted from the glands traps particles and cilia transport them down to the pharynx for swallowing, this process is known as the [[Respiratory Epithelium - Anatomy & Physiology#Mucociliary Escalator|Mucociliary Escalator]].
*The nasal cavity offers further protection via the Sneezing reflex .

==Species Differences==

*The nasal cavity in the '''sheep''' is highly vascularised, with any damage to the epithelium resulting in severe [[General Pathology - Haemorrhage|haemorrhage]].
*'''Cattle''' have a smaller nasal cavity compared to the horse.
*There are many variations to the entire [[Avian Respiration - Anatomy & Physiology|'''Avian''' respiratory tract]].
*The [[Respiration in Non-Homeotherms - Anatomy & Physiology|Respiratory Systems of non-Homeotherms]] are also very different to that of mammals.

==Links==

*[[Nasal Cavity - Pathology]]

==References==

*{{citation|initiallast = Dyce|initialfirst = K.M|2last = Sack|2first = W.O|finallast = Wensing|finalfirst = C.J.G|year = 2002|title = Textbook of Veterinary Anatomy|ed =3rd|city = Philadelphia|pub = Saunders}}

Paranasal Sinuses - Anatomy & Physiology

2008-08-15T09:26:28Z

Lwyacem: /* Species Differences */

Trachea - Anatomy & Physiology

2008-08-15T09:25:58Z

Lwyacem: /* Species Differences */

{{toplink
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|linkpage =Cardiorespiratory System - Anatomy & Physiology
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|pagetype =Anatomy
}}
 

[[Image:TracheaRatlowpower.jpg|right|thumb|400px|©RVC 2008]]

==Introduction==

The trachea is the tube linking the cricoid [[Bones and Cartilage - Anatomy & Physiology#Types of Cartilage|cartilage]] of the [[Larynx - Anatomy & Physiology |larynx]] to the [[Bronchi and bronchioles - Anatomy & Physiology|bronchi]], forming part of the conducting system which transports air from the external environment to the [[Lungs - Anatomy & Physiology|lungs]]. The [[Oesophagus - Anatomy & Physiology|oesophagus]] lies dorsally to the trachea.
The cervical part of the trachea lies generally in the median position, although this varies slightly depending on the position of the head.
The thoracic part of the trachea crosses the aortic arch, thus it's positioning is moved slightly to the right at this level.

The trachea bifurcates to form the two [[Bronchi and bronchioles - Anatomy & Physiology|bronchi]] at the level of the 4th-6th inter[[Ribs and Sternum - Anatomy & Physiology#Costae|costal]] space.

==Structure==

*The trachea contains numerous rings of [[Bones and Cartilage - Anatomy & Physiology#Hyaline Cartilage|hyaline cartilage]] which are C-shaped, being dorsally incomplete, connected to eachother by elastic connective tissue. The ends of the incomplete rings are joined by smooth muscle - ''Trachealis'' muscle.
**The structural conformation of the trachea prevents collapse due to traction forces, whilst allowing it to adjust in length and diameter as the neck moves and the [[Diaphragm - Anatomy & Physiology|diaphragm]] contracts.
*The trachea's walls are made up of a number of layers: Inner Mucosa, Fibrocartilaginous middle layer, and and adventitia (in the neck) or serosa (in the thorax).
*The inner mucosa contains glands which produce mucus. This mucus traps debris and is constantly moved upwards towards the [[Oral Cavity - Oropharynx - Anatomy & Physiology|oropharynx]] where it is swallowed. This mechanism is known as the [[Respiratory Epithelium - Anatomy & Physiology#Mucociliary Escalator|''Muco-Ciliary escalator'']].

==Function==

*Transporting air for respiration from the [[Larynx - Anatomy & Physiology|larynx]] to the [[Bronchi and bronchioles - Anatomy & Physiology|bronchi]].

==Histology==

<center><gallery>
Image:TrachealWallRAT.jpg|'''Tracheal Wall (Rat)'''©RVC 2008
Image:TrachealWallLiningRAT.jpg|'''Epithelial Lining of the Tracheal Wall (Rat)'''©RVC 2008
Image:TrachealWallstainedforelasticfibresCAT.jpg|'''Tracheal Wall stained for elastic fibres (Cat).'''©RVC 2008

</gallery></center>

==Species Differences==

*In the '''Dog and Cat''' the C-Shaped rings are joined by muscle which is placed externally, rather than internally as is normal for the other species.
*In [[Avian Respiration - Anatomy & Physiology|'''avian]] species''' the trachea is composed of tightly stacked rings of [[Bones and Cartilage - Anatomy & Physiology#Types of Cartilage|cartilage]], which are complete with no dorsal space. They overlap considerably.
*The [[Respiration in Non-Homeotherms - Anatomy & Physiology|Respiratory Systems of non-Homeotherms]] are also very different to that of mammals.

==Links==

*[[Trachea - Pathology]]

*[[Syrinx - Anatomy & Physiology|The Syrinx- avian vocalisation]]

==References==

*{{citation|initiallast = Dyce|initialfirst = K.M|2last = Sack|2first = W.O|finallast = Wensing|finalfirst = C.J.G|year = 2002|title = Textbook of Veterinary Anatomy|ed =3rd|city = Philadelphia|pub = Saunders}}

Bronchi and Bronchioles - Anatomy & Physiology

2008-08-15T09:25:42Z

Lwyacem:

{{toplink
|backcolour = D1EEEE
|linkpage =Cardiorespiratory System - Anatomy & Physiology
|linktext =Cardiorespiratory System
|maplink = Cardiorespiratory (Content Map) - Anatomy & Physiology
|pagetype =Anatomy
}}
 

[[Image:Routeofairthroughrespiratorysystem.jpg|right|thumb|250px|'''Schematic Diagram showing the route air takes through the respiratory system''']]

==Introduction==

The trachea bifurcates at the levels of the 4th-6th intercostal space, approximatley halfway between the thoracic inlet and the [[Diaphragm - Anatomy & Physiology|diaphragm]]. dividing into two Principle 'Bronchi', tubes which conduct air into the lngs. These further divide into smaller bronchi and bronchioles.
The initial division after entry to the lung is known as the '''Principle Bronchi''', and this further divides into two ''Lobar Bronchi' for the left lung, and into four ''Lobar Bronchi'' for the right lung.

==Structure==

*The structure of the larger bronchi is identical to that of the [[Trachea - Anatomy & Physiology|trachea]]. On the smaller bronchi the C-shaped cartilage rings are gradually replaced by irregular ''plaques'' of cartilage. Bronchioles have no cartilage at all.
*The bronchioles are less than 1mm in diameter, and undergo further divisions, the last of which is characterised by the loss of goblet cells.

==Function==

*The bronchi and bronchioles are parts of the ''''Conduction Zone'''' of the respiratory system - allowing the passage of air from the external environment into the lungs where gaseous exchange can take place.
*Some of the Bronchioles have alveoli scattered along their length, and thus form part of the ''''Respiratory Zone'''' - a site for gaseous exchange.

==Histology==
[[Image:Bronchiole Histology.jpg|right|thumb|350px|©Nottingham 2008]]

*The histology of the '''Bronchi''' is almost identical to that of the [[Trachea - Anatomy & Physiology|trachea]] - the lumen of the bronchus is lined by a pseudostratified epithelium, including goblet cells and serous cells.
Beneath the narrow layer of connective tissue under the epithelium lie well-developed spiral bands of [[Muscles - Anatomy & Physiology#Smooth Muscle|smooth muscle]].
*The '''Bronchioles''' have no [[Bones and Cartilage - Anatomy & Physiology#Types of Cartilage|cartilage]] rings but have well developed [[Muscles - Anatomy & Physiology|muscular]] walls to enclose the lumen. The epithelium is reduced to cuboidal, and in the normal animal it contains no mucus secreting glands. There are many [[Lymph Nodes - Anatomy & Physiology|lymphoid]] nodules beneath the epithelial layer.
*'''Respiratory Bronchioles''' have few alveoli scattered along the length, at the entrance of which is ''simple squamous'' epithelium, and bronchial [[Muscles - Anatomy & Physiology#Smooth Muscle|smooth muscle]] bundles.

==Species Differences==

*Between species the diameter of the bronchi and bronchioles vary greatly and more significantly than the variations of the [[Trachea - Anatomy & Physiology|trachea]].
*The number of bronchial divisions before bronchioles are present varies by species - small mammals such as mice may have only 4/5 generations, whereas 12+ may be necessary in larger animals.
*[[Avian Respiration - Anatomy & Physiology|Avian Respiration]] is very different to that of mammals.
*The [[Respiration in Non-Homeotherms - Anatomy & Physiology|Respiratory Systems of non-Homeotherms]] are also very different to that of mammals.

==Links==
[[Bronchi and Bronchioles - Pathology]]

==References==

*{{citation|initiallast = Dyce|initialfirst = K.M|2last = Sack|2first = W.O|finallast = Wensing|finalfirst = C.J.G|year = 2002|title = Textbook of Veterinary Anatomy|ed =3rd|city = Philadelphia|pub = Saunders}}

*{{citation|initiallast = Budras|initialfirst = K.D|2last = McCarthy|2first = P.H|3last = Fricke|3first = W|finallast = Richter|finalfirst = R|year = 2002|title = Anatomy of the Dog|ed =4th|city = Hannover|pub = Schlutersche GmbH & Co. KG, Verlag und Druckerei}}

Lungs - Anatomy & Physiology

2008-08-15T09:25:22Z

Lwyacem: /* Species Differences */

{{toplink
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|linkpage =Cardiorespiratory System - Anatomy & Physiology
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}}
 

[[Image:Doglungdeflated.jpg|right|thumb|250px|©RVC 2008]]

==Introduction==

[[Image:Doglunginflated.jpg|right|thumb|250px|©RVC 2008]]
The lungs are the site for [[Gas Exchange - Anatomy & Physiology|gaseous exchange]], and are situated within the thoracic cavity. They occupy approximatley 5% of the body volume in mammals when relaxed, but generally have no fixed size or shape since their volume is constantly changing with the processes of [[Ventilation - Anatomy & Physiology#Inspiration|inspiration]] and [[Ventilation - Anatomy & Physiology#Expiration|expiration]].

The lungs, along with the [[Larynx - Anatomy & Physiology|larynx]] and [[Trachea - Anatomy & Physiology|trachea]], develop from a ventral respiratory tract. After separation from the developing [[Oesophagus - Anatomy & Physiology|oesophagus]], two lung buds develop, which undergo divisions as they grow, forming the beginnings of the [[Bronchi and bronchioles - Anatomy & Physiology|bronchial]] tree. This process is not completed by [[Parturition - Normal Parturition - Anatomy & Physiology|parturition]].

==Structure==

*The left and right lungs lie within their [[Pleural cavity and membranes - Anatomy & Physiology|pleural]] sac and are only attached by their roots, to the [[Mediastinum - Anatomy & Physiology|mediastinum]], so they are fairly free within the thoracic cavity.
*The right lung is always larger than the left, due to the positioning of the [[Heart - Anatomy & Physiology|heart]]. The apex of the lungs is their cranial point.
*In most species the lungs are divided into lobes by the [[Bronchi and bronchioles - Anatomy & Physiology|bronchial]] tree:
**'''Left Lung''' = Cranial and Caudal lobes.
**'''Right Lung''' = Cranial, Caudal, Middle and Accessory lobes. The cranial lobe is further divided by an external fissure.[[Image:Routeofairthroughrespiratorysystem.jpg|right|thumb|200px|'''Schematic Diagram showing the route air takes through the respiratory system''']]
*The bulk of the lung consists of [[Bronchi and bronchioles - Anatomy & Physiology|bronchi]], [[Anatomy of Blood Vessels - Anatomy & Physiology|blood vessels]] and connective tissue. The terminal [[Bronchi and bronchioles - Anatomy & Physiology|bronchioles]] have alveoli scattered along their length, and are continued by alveolar ducts, alveolar sacs and finally alveoli.
**'''Alveolar Ducts''': These have alveoli which open on all of it's sides, they have no 'walls' as such. Openings to individual alveoli are guarded by [[Muscles - Anatomy & Physiology#Smooth Muscle|smooth muscle]].
**'''Alveolar Sacs''': These are rotunda-like areas on the end of each alveolar ducts which are usually present in clusters.
**'''Alveoli''': These are minute, polygonal chambers, whose diameter changes with the processes of [[Ventilation - Anatomy & Physiology#Inspiration|inspiration]] and [[Ventilation - Anatomy & Physiology#Expiration|expiration]], and varies by species. The wall of the alveoli is extremely thin, consisting of 2 irregular layers of epithelial sheets, 'sandwiching' a network of capillaries. Thus the ''Blood-Gas Barrier'' is just a single basal lamina - ideal for [[Gas Exchange - Anatomy & Physiology|gaseous exchange]]. The alveolar interstitium is formed from connective tissue fibres and cells, which include collagen fibrils and elastin fibres.

==Function==

*[[Gas Exchange - Anatomy & Physiology|Gas Exchange]]

==Vasculature==

*The '''Pulmonary Arteries''' follow the bronchi while the '''Pulmonary veins''' sometimes run separately.
*'''Bronchial arteries''' from the Aorta supply the bronchi, and '''Bronchial veins''' may drain this blood to the [[Structure of the Heart - Anatomy & Physiology#Right Atrium|right atrium]] via the '''Azygous Vein'''. More often the blood from the bronchi drains directly to the [[Structure of the Heart - Anatomy & Physiology#Left Atrium|left atrium]].

==Innervation==

* Nervous supply to the lung is via the '''Pulmonary Plexus''' within the [[Mediastinum - Anatomy & Physiology|mediastinum]].
*The Pulmonary Plexus consists of Sympathetic Fibres largely from the Stellate Ganglion, and Parasympathetic Fibres from the [[Nervous System - CNS - Anatomy & Physiology#Innervation - Cranial Nerves|Vagus nerve]].

==Lymphatics==

* Lymph drains to the '''Tracheobronchial''' and '''Mediastinal''' [[Lymph Nodes - Anatomy & Physiology|lymph nodes]].

==Histology==

<center><gallery>
Image:Lungadultlowmag.jpg|'''Lung (adult)'''©RVC 2008
Image:SEMAdultSheepLung.jpg|'''SEM of Adult Sheep Lung'''©RVC 2008
Image:Bronchuslowpower.jpg|'''Bronchus'''©RVC 2008
Image:Bronchuslowpower2.jpg|'''Bronchus'''©RVC 2008
Image:Alveoli.jpg|'''Alveoli'''©RVC 2008
Image:Alveoli2.jpg|'''Alveoli'''©RVC 2008
</gallery></center>

==Species Differences==

* Externally the lungs of the '''Horse''' show almost no lobation. Internally the right lung of the horse lacks a Middle Lobe.
*The lungs of '''Ruminants''' and '''Pigs''' are obviously lobed.
*The fissures between lobes (''Interlobar fissures'') are deeper in the dog and cat lung compared to other species.
*[[Avian Respiration - Anatomy & Physiology|Avian Respiration]] has many fundamental differences to mammalian respiration.
*The [[Respiration in Non-Homeotherms - Anatomy & Physiology|Respiratory Systems of non-Homeotherms]] are also very different to that of mammals.

==Links==

[[Lungs - Pathology]]

==References==

*{{citation|initiallast = Dyce|initialfirst = K.M|2last = Sack|2first = W.O|finallast = Wensing|finalfirst = C.J.G|year = 2002|title = Textbook of Veterinary Anatomy|ed =3rd|city = Philadelphia|pub = Saunders}}

Pleural Cavity and Membranes - Anatomy & Physiology

2008-08-15T09:24:54Z

Lwyacem: /* Species Differences */

{{toplink
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|linkpage =Cardiorespiratory System - Anatomy & Physiology
|linktext =Cardiorespiratory System
|maplink = Cardiorespiratory (Content Map) - Anatomy & Physiology
|pagetype =Anatomy
}}
 
==Introduction==

The surface of the inner wall of all of the body cavities is lined by a serous membrane which consists of a single layer of flat epithelium with a thin underlying propria (connective tissue). Within the thoracic cavity, this is known as the ''Pleura''.

The '''Visceral Pleura''' which coats the outer surface of the lung is derived from the ''Splanchnic Mesoderm''. The '''Parietal Pleura''' lining the thoracic cavity is deried from ''Somatic Mesoderm''

The Pleural Cavity is potential space between the two areas of pleural membrane.

==Pleural Membranes==
===Structure of the Pleural Membranes===
[[Image:PleuralMembranesSchematic.jpg|right|thumb|350px|'''Schematic Diagram of the Pleural Membranes''' (Cross section through thoracic cavity at the level of the heart)]]

*Each [[Lungs - Anatomy & Physiology|lung]] is placed within a separate layer of membrane, thus there are two pleural sacs.
*The space between the two sacs is known as the [[Mediastinum - Anatomy & Physiology|Mediastinum]], and is almost in the midline of the thorax.
*The pleura covering the surface of the lung is known as '''Pulmonary Pleura''' or '''Visceral Pleura'''. This becomes continuous with the '''Mediastinal Pleura''' as it wraps around the [[Lungs - Anatomy & Physiology|lung]].
*The '''Diaphragmatic''' and '''Costal Pleura''' are continuous with the Mediastinal Pleura. Together, these three membranes are the '''Parietal Pleura'''.
*Between the Parietal and Visceral Pleura is the '''Intrapleural Space''', or '''Pleural Cavity'''. This contains a small amount of serous fluid which establishes adhesion between the layers and allows smooth movement between the lung and chest wall, and between individual lobes of the [[Lungs - Anatomy & Physiology|lungs]].
*The [[Heart - Anatomy & Physiology|Heart]] is invested in a Parietal and Visceral layer of [[Structure of the Heart - Anatomy & Physiology#Pericardium|'''Pericardium''']] with the '''Pericardial Space''' separating the two membranes.
*Cranially the Costal and Mediastinal Pleura adjoin to form a 'dome' of pleura which extends cranially to the thoracic inlet. This is known as the '''Cupulae Pleurae'''. This region is only protected by soft tissue, and thus is vulnerable to injury.
*Within the pleural sac encasing the right [[Lungs - Anatomy & Physiology|lung]], there is a fold which encases the Vena Cava. It is known as the '''Plica Venae Cavae'''.
*The Pleural Membranes are larger than the [[Lungs - Anatomy & Physiology|lungs]] which they encase, thus there are areas where the facing surfaces of parietal pleura touch eachother. These are known as '''Pleural Recesses'''. One example is the '''Costodiaphragmatic Recess''', the space between the costal and [[Diaphragm - Anatomy & Physiology|diaphragm]]atic pleura. The volume of the recess varies to a point due to the phase of [[Ventilation - Anatomy & Physiology#Inspiration|inspiration]]/[[Ventilation - Anatomy & Physiology#Expiration|expiration]].

===Pleural Membrane Function===

*The Pleural Cavity is filled with a small amount of serous fluid which forms a thin film of liquid between the pleural layers. This is vital in that in prevents separation of the two pleural layers and lubricates the surface, so the [[Lungs - Anatomy & Physiology|lungs]] can move easily within the thoracic cavity.
*The Pleural Fluid also provides surface tension, keeping the [[Lungs - Anatomy & Physiology|lung]] suitably close to the wall of the thorax, despite the the lungs not being directly fixed to it. The pleurae thus allow the volume of the [[Lungs - Anatomy & Physiology|lungs]] to change with the volume of the thoracic cavity, enabling [[Ventilation - Anatomy & Physiology|Ventilation]].
*The left and right pleural sacs are separate so that in the event of one being punctured, the other [[Lungs - Anatomy & Physiology|lung]] can continue to function effectively.

==Vasculature==

*The Pleural membranes are supplied by the '''Bronchial''' and '''Pulmonary Arteries'''.

==Innervation==

*'''Parietal Pleura''' is innervated by the intercostal nerves, with the Mediastinal and Diaphragmatic pleura also innervated by the Phrenic Nerve.
*'''Visceral pleura''' is innervated by the Vagus nerve and sympathetic fibres. It is insensitive to pain stimuli.

==Species Differences==
[[Image:Dogthorax1.jpg|right|thumb|350px|''The mediastinum is visible in this dog dissection, left lung removed. ©RVC 2008]]
*In '''Cattle''' the [[Mediastinum - Anatomy & Physiology|Mediastinum]] is a tough membrane, in contrast to '''Horses, Dogs''' and '''Cats''' where it is rather thin and more delicate.
*Birds do not have a pleural cavity as [[Avian Respiration - Anatomy & Physiology|Avian lungs]] do not have the capacity to inflate.
*The [[Respiration in Non-Homeotherms - Anatomy & Physiology|Respiratory Systems of non-Homeotherms]] are also very different to that of mammals.

==Links==

[[Pleural Cavity and Membranes - Pathology]]

==References==

*{{citation|initiallast = Dyce|initialfirst = K.M|2last = Sack|2first = W.O|finallast = Wensing|finalfirst = C.J.G|year = 2002|title = Textbook of Veterinary Anatomy|ed =3rd|city = Philadelphia|pub = Saunders}}

*{{citation|initiallast = Budras|initialfirst = K.D|2last = McCarthy|2first = P.H|3last = Fricke|3first = W|finallast = Richter|finalfirst = R|year = 2002|title = Anatomy of the Dog|ed =4th|city = Hannover|pub = Schlutersche GmbH & Co. KG, Verlag und Druckerei}}

Pleural Cavity and Membranes - Anatomy & Physiology

2008-08-15T09:24:37Z

Lwyacem:

{{toplink
|backcolour = D1EEEE
|linkpage =Cardiorespiratory System - Anatomy & Physiology
|linktext =Cardiorespiratory System
|maplink = Cardiorespiratory (Content Map) - Anatomy & Physiology
|pagetype =Anatomy
}}
 
==Introduction==

The surface of the inner wall of all of the body cavities is lined by a serous membrane which consists of a single layer of flat epithelium with a thin underlying propria (connective tissue). Within the thoracic cavity, this is known as the ''Pleura''.

The '''Visceral Pleura''' which coats the outer surface of the lung is derived from the ''Splanchnic Mesoderm''. The '''Parietal Pleura''' lining the thoracic cavity is deried from ''Somatic Mesoderm''

The Pleural Cavity is potential space between the two areas of pleural membrane.

==Pleural Membranes==
===Structure of the Pleural Membranes===
[[Image:PleuralMembranesSchematic.jpg|right|thumb|350px|'''Schematic Diagram of the Pleural Membranes''' (Cross section through thoracic cavity at the level of the heart)]]

*Each [[Lungs - Anatomy & Physiology|lung]] is placed within a separate layer of membrane, thus there are two pleural sacs.
*The space between the two sacs is known as the [[Mediastinum - Anatomy & Physiology|Mediastinum]], and is almost in the midline of the thorax.
*The pleura covering the surface of the lung is known as '''Pulmonary Pleura''' or '''Visceral Pleura'''. This becomes continuous with the '''Mediastinal Pleura''' as it wraps around the [[Lungs - Anatomy & Physiology|lung]].
*The '''Diaphragmatic''' and '''Costal Pleura''' are continuous with the Mediastinal Pleura. Together, these three membranes are the '''Parietal Pleura'''.
*Between the Parietal and Visceral Pleura is the '''Intrapleural Space''', or '''Pleural Cavity'''. This contains a small amount of serous fluid which establishes adhesion between the layers and allows smooth movement between the lung and chest wall, and between individual lobes of the [[Lungs - Anatomy & Physiology|lungs]].
*The [[Heart - Anatomy & Physiology|Heart]] is invested in a Parietal and Visceral layer of [[Structure of the Heart - Anatomy & Physiology#Pericardium|'''Pericardium''']] with the '''Pericardial Space''' separating the two membranes.
*Cranially the Costal and Mediastinal Pleura adjoin to form a 'dome' of pleura which extends cranially to the thoracic inlet. This is known as the '''Cupulae Pleurae'''. This region is only protected by soft tissue, and thus is vulnerable to injury.
*Within the pleural sac encasing the right [[Lungs - Anatomy & Physiology|lung]], there is a fold which encases the Vena Cava. It is known as the '''Plica Venae Cavae'''.
*The Pleural Membranes are larger than the [[Lungs - Anatomy & Physiology|lungs]] which they encase, thus there are areas where the facing surfaces of parietal pleura touch eachother. These are known as '''Pleural Recesses'''. One example is the '''Costodiaphragmatic Recess''', the space between the costal and [[Diaphragm - Anatomy & Physiology|diaphragm]]atic pleura. The volume of the recess varies to a point due to the phase of [[Ventilation - Anatomy & Physiology#Inspiration|inspiration]]/[[Ventilation - Anatomy & Physiology#Expiration|expiration]].

===Pleural Membrane Function===

*The Pleural Cavity is filled with a small amount of serous fluid which forms a thin film of liquid between the pleural layers. This is vital in that in prevents separation of the two pleural layers and lubricates the surface, so the [[Lungs - Anatomy & Physiology|lungs]] can move easily within the thoracic cavity.
*The Pleural Fluid also provides surface tension, keeping the [[Lungs - Anatomy & Physiology|lung]] suitably close to the wall of the thorax, despite the the lungs not being directly fixed to it. The pleurae thus allow the volume of the [[Lungs - Anatomy & Physiology|lungs]] to change with the volume of the thoracic cavity, enabling [[Ventilation - Anatomy & Physiology|Ventilation]].
*The left and right pleural sacs are separate so that in the event of one being punctured, the other [[Lungs - Anatomy & Physiology|lung]] can continue to function effectively.

==Vasculature==

*The Pleural membranes are supplied by the '''Bronchial''' and '''Pulmonary Arteries'''.

==Innervation==

*'''Parietal Pleura''' is innervated by the intercostal nerves, with the Mediastinal and Diaphragmatic pleura also innervated by the Phrenic Nerve.
*'''Visceral pleura''' is innervated by the Vagus nerve and sympathetic fibres. It is insensitive to pain stimuli.

==Species Differences==
[[Image:Dogthorax1.jpg|right|thumb|350px|''The mediastinum is visible in this dog dissection, left lung removed. ©RVC 2008]]
*In '''Cattle''' the [[Mediastinum - Anatomy & Physiology|Mediastinum]] is a tough membrane, in contrast to '''Horses, Dogs''' and '''Cats''' where it is rather thin and more delicate.
*Birds do not have a pleural cavity as [[Avian Respiration - Anatomy & Physiology|Avian lungs]] do not have the capacity to inflate.
*The [[Respiration in Non-Homeotherms - Anatomy & Physiology|Respiratory Systems]] of non-Homeotherms]] are also very different to that of mammals.

==Links==

[[Pleural Cavity and Membranes - Pathology]]

==References==

*{{citation|initiallast = Dyce|initialfirst = K.M|2last = Sack|2first = W.O|finallast = Wensing|finalfirst = C.J.G|year = 2002|title = Textbook of Veterinary Anatomy|ed =3rd|city = Philadelphia|pub = Saunders}}

*{{citation|initiallast = Budras|initialfirst = K.D|2last = McCarthy|2first = P.H|3last = Fricke|3first = W|finallast = Richter|finalfirst = R|year = 2002|title = Anatomy of the Dog|ed =4th|city = Hannover|pub = Schlutersche GmbH & Co. KG, Verlag und Druckerei}}

Lungs - Anatomy & Physiology

2008-08-15T09:24:16Z

Lwyacem:

{{toplink
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|linkpage =Cardiorespiratory System - Anatomy & Physiology
|linktext =Cardiorespiratory System
|maplink = Cardiorespiratory (Content Map) - Anatomy & Physiology
|pagetype =Anatomy
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[[Image:Doglungdeflated.jpg|right|thumb|250px|©RVC 2008]]

==Introduction==

[[Image:Doglunginflated.jpg|right|thumb|250px|©RVC 2008]]
The lungs are the site for [[Gas Exchange - Anatomy & Physiology|gaseous exchange]], and are situated within the thoracic cavity. They occupy approximatley 5% of the body volume in mammals when relaxed, but generally have no fixed size or shape since their volume is constantly changing with the processes of [[Ventilation - Anatomy & Physiology#Inspiration|inspiration]] and [[Ventilation - Anatomy & Physiology#Expiration|expiration]].

The lungs, along with the [[Larynx - Anatomy & Physiology|larynx]] and [[Trachea - Anatomy & Physiology|trachea]], develop from a ventral respiratory tract. After separation from the developing [[Oesophagus - Anatomy & Physiology|oesophagus]], two lung buds develop, which undergo divisions as they grow, forming the beginnings of the [[Bronchi and bronchioles - Anatomy & Physiology|bronchial]] tree. This process is not completed by [[Parturition - Normal Parturition - Anatomy & Physiology|parturition]].

==Structure==

*The left and right lungs lie within their [[Pleural cavity and membranes - Anatomy & Physiology|pleural]] sac and are only attached by their roots, to the [[Mediastinum - Anatomy & Physiology|mediastinum]], so they are fairly free within the thoracic cavity.
*The right lung is always larger than the left, due to the positioning of the [[Heart - Anatomy & Physiology|heart]]. The apex of the lungs is their cranial point.
*In most species the lungs are divided into lobes by the [[Bronchi and bronchioles - Anatomy & Physiology|bronchial]] tree:
**'''Left Lung''' = Cranial and Caudal lobes.
**'''Right Lung''' = Cranial, Caudal, Middle and Accessory lobes. The cranial lobe is further divided by an external fissure.[[Image:Routeofairthroughrespiratorysystem.jpg|right|thumb|200px|'''Schematic Diagram showing the route air takes through the respiratory system''']]
*The bulk of the lung consists of [[Bronchi and bronchioles - Anatomy & Physiology|bronchi]], [[Anatomy of Blood Vessels - Anatomy & Physiology|blood vessels]] and connective tissue. The terminal [[Bronchi and bronchioles - Anatomy & Physiology|bronchioles]] have alveoli scattered along their length, and are continued by alveolar ducts, alveolar sacs and finally alveoli.
**'''Alveolar Ducts''': These have alveoli which open on all of it's sides, they have no 'walls' as such. Openings to individual alveoli are guarded by [[Muscles - Anatomy & Physiology#Smooth Muscle|smooth muscle]].
**'''Alveolar Sacs''': These are rotunda-like areas on the end of each alveolar ducts which are usually present in clusters.
**'''Alveoli''': These are minute, polygonal chambers, whose diameter changes with the processes of [[Ventilation - Anatomy & Physiology#Inspiration|inspiration]] and [[Ventilation - Anatomy & Physiology#Expiration|expiration]], and varies by species. The wall of the alveoli is extremely thin, consisting of 2 irregular layers of epithelial sheets, 'sandwiching' a network of capillaries. Thus the ''Blood-Gas Barrier'' is just a single basal lamina - ideal for [[Gas Exchange - Anatomy & Physiology|gaseous exchange]]. The alveolar interstitium is formed from connective tissue fibres and cells, which include collagen fibrils and elastin fibres.

==Function==

*[[Gas Exchange - Anatomy & Physiology|Gas Exchange]]

==Vasculature==

*The '''Pulmonary Arteries''' follow the bronchi while the '''Pulmonary veins''' sometimes run separately.
*'''Bronchial arteries''' from the Aorta supply the bronchi, and '''Bronchial veins''' may drain this blood to the [[Structure of the Heart - Anatomy & Physiology#Right Atrium|right atrium]] via the '''Azygous Vein'''. More often the blood from the bronchi drains directly to the [[Structure of the Heart - Anatomy & Physiology#Left Atrium|left atrium]].

==Innervation==

* Nervous supply to the lung is via the '''Pulmonary Plexus''' within the [[Mediastinum - Anatomy & Physiology|mediastinum]].
*The Pulmonary Plexus consists of Sympathetic Fibres largely from the Stellate Ganglion, and Parasympathetic Fibres from the [[Nervous System - CNS - Anatomy & Physiology#Innervation - Cranial Nerves|Vagus nerve]].

==Lymphatics==

* Lymph drains to the '''Tracheobronchial''' and '''Mediastinal''' [[Lymph Nodes - Anatomy & Physiology|lymph nodes]].

==Histology==

<center><gallery>
Image:Lungadultlowmag.jpg|'''Lung (adult)'''©RVC 2008
Image:SEMAdultSheepLung.jpg|'''SEM of Adult Sheep Lung'''©RVC 2008
Image:Bronchuslowpower.jpg|'''Bronchus'''©RVC 2008
Image:Bronchuslowpower2.jpg|'''Bronchus'''©RVC 2008
Image:Alveoli.jpg|'''Alveoli'''©RVC 2008
Image:Alveoli2.jpg|'''Alveoli'''©RVC 2008
</gallery></center>

==Species Differences==

* Externally the lungs of the '''Horse''' show almost no lobation. Internally the right lung of the horse lacks a Middle Lobe.
*The lungs of '''Ruminants''' and '''Pigs''' are obviously lobed.
*The fissures between lobes (''Interlobar fissures'') are deeper in the dog and cat lung compared to other species.
*[[Avian Respiration - Anatomy & Physiology|Avian Respiration]] has many fundamental differences to mammalian respiration.
*The [[Respiration in Non-Homeotherms - Anatomy & Physiology|Respiratory Systems]] of non-Homeotherms]] are also very different to that of mammals.

==Links==

[[Lungs - Pathology]]

==References==

*{{citation|initiallast = Dyce|initialfirst = K.M|2last = Sack|2first = W.O|finallast = Wensing|finalfirst = C.J.G|year = 2002|title = Textbook of Veterinary Anatomy|ed =3rd|city = Philadelphia|pub = Saunders}}

Bronchi and Bronchioles - Anatomy & Physiology

2008-08-15T09:23:18Z

Lwyacem:

{{toplink
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|linkpage =Cardiorespiratory System - Anatomy & Physiology
|linktext =Cardiorespiratory System
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|pagetype =Anatomy
}}
 

[[Image:Routeofairthroughrespiratorysystem.jpg|right|thumb|250px|'''Schematic Diagram showing the route air takes through the respiratory system''']]

==Introduction==

The trachea bifurcates at the levels of the 4th-6th intercostal space, approximatley halfway between the thoracic inlet and the [[Diaphragm - Anatomy & Physiology|diaphragm]]. dividing into two Principle 'Bronchi', tubes which conduct air into the lngs. These further divide into smaller bronchi and bronchioles.
The initial division after entry to the lung is known as the '''Principle Bronchi''', and this further divides into two ''Lobar Bronchi' for the left lung, and into four ''Lobar Bronchi'' for the right lung.

==Structure==

*The structure of the larger bronchi is identical to that of the [[Trachea - Anatomy & Physiology|trachea]]. On the smaller bronchi the C-shaped cartilage rings are gradually replaced by irregular ''plaques'' of cartilage. Bronchioles have no cartilage at all.
*The bronchioles are less than 1mm in diameter, and undergo further divisions, the last of which is characterised by the loss of goblet cells.

==Function==

*The bronchi and bronchioles are parts of the ''''Conduction Zone'''' of the respiratory system - allowing the passage of air from the external environment into the lungs where gaseous exchange can take place.
*Some of the Bronchioles have alveoli scattered along their length, and thus form part of the ''''Respiratory Zone'''' - a site for gaseous exchange.

==Histology==
[[Image:Bronchiole Histology.jpg|right|thumb|350px|©Nottingham 2008]]

*The histology of the '''Bronchi''' is almost identical to that of the [[Trachea - Anatomy & Physiology|trachea]] - the lumen of the bronchus is lined by a pseudostratified epithelium, including goblet cells and serous cells.
Beneath the narrow layer of connective tissue under the epithelium lie well-developed spiral bands of [[Muscles - Anatomy & Physiology#Smooth Muscle|smooth muscle]].
*The '''Bronchioles''' have no [[Bones and Cartilage - Anatomy & Physiology#Types of Cartilage|cartilage]] rings but have well developed [[Muscles - Anatomy & Physiology|muscular]] walls to enclose the lumen. The epithelium is reduced to cuboidal, and in the normal animal it contains no mucus secreting glands. There are many [[Lymph Nodes - Anatomy & Physiology|lymphoid]] nodules beneath the epithelial layer.
*'''Respiratory Bronchioles''' have few alveoli scattered along the length, at the entrance of which is ''simple squamous'' epithelium, and bronchial [[Muscles - Anatomy & Physiology#Smooth Muscle|smooth muscle]] bundles.

==Species Differences==

*Between species the diameter of the bronchi and bronchioles vary greatly and more significantly than the variations of the [[Trachea - Anatomy & Physiology|trachea]].
*The number of bronchial divisions before bronchioles are present varies by species - small mammals such as mice may have only 4/5 generations, whereas 12+ may be necessary in larger animals.
*[[Avian Respiration - Anatomy & Physiology|Avian Respiration]] is very different to that of mammals.
*The [[Respiration in Non-Homeotherms - Anatomy & Physiology|Respiratory Systems]] of non-Homeotherms]] are also very different to that of mammals.

==Links==
[[Bronchi and Bronchioles - Pathology]]

==References==

*{{citation|initiallast = Dyce|initialfirst = K.M|2last = Sack|2first = W.O|finallast = Wensing|finalfirst = C.J.G|year = 2002|title = Textbook of Veterinary Anatomy|ed =3rd|city = Philadelphia|pub = Saunders}}

*{{citation|initiallast = Budras|initialfirst = K.D|2last = McCarthy|2first = P.H|3last = Fricke|3first = W|finallast = Richter|finalfirst = R|year = 2002|title = Anatomy of the Dog|ed =4th|city = Hannover|pub = Schlutersche GmbH & Co. KG, Verlag und Druckerei}}

Trachea - Anatomy & Physiology

2008-08-15T09:22:10Z

Lwyacem:

{{toplink
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|linkpage =Cardiorespiratory System - Anatomy & Physiology
|linktext =Cardiorespiratory System
|maplink = Cardiorespiratory (Content Map) - Anatomy & Physiology
|pagetype =Anatomy
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[[Image:TracheaRatlowpower.jpg|right|thumb|400px|©RVC 2008]]

==Introduction==

The trachea is the tube linking the cricoid [[Bones and Cartilage - Anatomy & Physiology#Types of Cartilage|cartilage]] of the [[Larynx - Anatomy & Physiology |larynx]] to the [[Bronchi and bronchioles - Anatomy & Physiology|bronchi]], forming part of the conducting system which transports air from the external environment to the [[Lungs - Anatomy & Physiology|lungs]]. The [[Oesophagus - Anatomy & Physiology|oesophagus]] lies dorsally to the trachea.
The cervical part of the trachea lies generally in the median position, although this varies slightly depending on the position of the head.
The thoracic part of the trachea crosses the aortic arch, thus it's positioning is moved slightly to the right at this level.

The trachea bifurcates to form the two [[Bronchi and bronchioles - Anatomy & Physiology|bronchi]] at the level of the 4th-6th inter[[Ribs and Sternum - Anatomy & Physiology#Costae|costal]] space.

==Structure==

*The trachea contains numerous rings of [[Bones and Cartilage - Anatomy & Physiology#Hyaline Cartilage|hyaline cartilage]] which are C-shaped, being dorsally incomplete, connected to eachother by elastic connective tissue. The ends of the incomplete rings are joined by smooth muscle - ''Trachealis'' muscle.
**The structural conformation of the trachea prevents collapse due to traction forces, whilst allowing it to adjust in length and diameter as the neck moves and the [[Diaphragm - Anatomy & Physiology|diaphragm]] contracts.
*The trachea's walls are made up of a number of layers: Inner Mucosa, Fibrocartilaginous middle layer, and and adventitia (in the neck) or serosa (in the thorax).
*The inner mucosa contains glands which produce mucus. This mucus traps debris and is constantly moved upwards towards the [[Oral Cavity - Oropharynx - Anatomy & Physiology|oropharynx]] where it is swallowed. This mechanism is known as the [[Respiratory Epithelium - Anatomy & Physiology#Mucociliary Escalator|''Muco-Ciliary escalator'']].

==Function==

*Transporting air for respiration from the [[Larynx - Anatomy & Physiology|larynx]] to the [[Bronchi and bronchioles - Anatomy & Physiology|bronchi]].

==Histology==

<center><gallery>
Image:TrachealWallRAT.jpg|'''Tracheal Wall (Rat)'''©RVC 2008
Image:TrachealWallLiningRAT.jpg|'''Epithelial Lining of the Tracheal Wall (Rat)'''©RVC 2008
Image:TrachealWallstainedforelasticfibresCAT.jpg|'''Tracheal Wall stained for elastic fibres (Cat).'''©RVC 2008

</gallery></center>

==Species Differences==

*In the '''Dog and Cat''' the C-Shaped rings are joined by muscle which is placed externally, rather than internally as is normal for the other species.
*In [[Avian Respiration - Anatomy & Physiology|'''avian]] species''' the trachea is composed of tightly stacked rings of [[Bones and Cartilage - Anatomy & Physiology#Types of Cartilage|cartilage]], which are complete with no dorsal space. They overlap considerably.
*The [[Respiration in Non-Homeotherms - Anatomy & Physiology|Respiratory Systems]] of non-Homeotherms]] are also very different to that of mammals.

==Links==

*[[Trachea - Pathology]]

*[[Syrinx - Anatomy & Physiology|The Syrinx- avian vocalisation]]

==References==

*{{citation|initiallast = Dyce|initialfirst = K.M|2last = Sack|2first = W.O|finallast = Wensing|finalfirst = C.J.G|year = 2002|title = Textbook of Veterinary Anatomy|ed =3rd|city = Philadelphia|pub = Saunders}}

Paranasal Sinuses - Anatomy & Physiology

2008-08-15T09:21:37Z

Lwyacem:

Nasal Cavity - Anatomy & Physiology

2008-08-15T09:21:22Z

Lwyacem:

{{toplink
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|linkpage =Cardiorespiratory System - Anatomy & Physiology
|linktext =Cardiorespiratory System
|maplink = Cardiorespiratory (Content Map) - Anatomy & Physiology
|pagetype =Anatomy
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[[Image:Nasal Cavities.jpg|thumb|right|300px|Nasal Cavities - Copyright David Bainbridge]]
==Introduction==

The respiratory tract begins with the ''nose'' which includes the external nose, internal nasal cavities and [[Paranasal sinuses - Anatomy & Physiology|paranasal sinuses]].
As well as being vital for transport of gases to the [[Cardiorespiratory System - Anatomy & Physiology#Lower Respiratory Tract|lower respiratory tract]], the nose is also the site for one of the special senses - [[Special Senses - Olfactory - Anatomy & Physiology|''Olfaction'']].

==Structure==

*The nose consists of the external nares with nasal [[Bones and Cartilage - Anatomy & Physiology#Structure and Function of Cartilage|cartilages]], the nasal cavity (including the nasal meatus and conchae), and the [[Paranasal sinuses - Anatomy & Physiology|paranasal sinuses]].

*The nasal cavity is essentially a tube with a wall established by several [[Skull and Facial Muscles - Anatomy & Physiology#Bones of the Skull|bones of the skull]]. The borders of the nasal cavity are as follows:

- ''Caudal'': cribrifrom plate of the [[Skull and Facial Muscles - Anatomy & Physiology#Ethmoid Bone (os ethmoidale)|ethmoid bone]]

- ''Ventral'': continuous with the nasopharynx

- ''Dorsal'': the maxilla and the palatine processes of the [[Skull and Facial Muscles - Anatomy & Physiology#Incisive Bone (os incisivium)|incisive bone]]

*Rostrally, the median septum is a continuation of the [[Skull and Facial Muscles - Anatomy & Physiology#Ethmoid Bone (os ethmoidale)|ethmoid bone]]. The median septum is made up of [[Bones and Cartilage - Anatomy & Physiology#Hyaline Cartilage|hyaline cartilage]], and divides the nasal cavity into left and right halves.

[[Image:DogHeadDissection.jpg|right|thumb|200px|The nasal cavity can be seen filled with conchae in this photograph of a canine head. ©Nottingham 2008]]

*The nasal cavity is occupied to a large extent by '''''Nasal conchae'''''. These are turbinate bones which project into the nasal cavity with the purpose of supporting the [[Special Senses - Olfactory - Anatomy & Physiology|olfactory]] mucus membranes and increasing the respiratory surface area, creating turbulence within the passing air. This helps to filtrate and warm or cool the air that passes through.

*The Conchae are [[Bones and Cartilage - Anatomy & Physiology#Types of Cartilage|cartilage]]nous or ossified scrolls which arise from the [[Skull and Facial Muscles - Anatomy & Physiology#Ethmoid Bone (os ethmoidale|''ethmoid bone'']]. They are covered with mucous membrane, under which is a layer of anastomosing blood vessels.
The nasal conchae are more complex in animals with a better sense of smell, as they increase the surface area of the [[Special Senses - Olfactory - Anatomy & Physiology|Olfactory]] region, further.

*There are dorsal and ventral conchae, the dorsal concha originating from the [[Skull and Facial Muscles - Anatomy & Physiology#Ethmoid Bone (os ethmoidale)|ethmoid bone]] and attaching to the maxilla, and the vental conchae originating from the [[Skull and Facial Muscles - Anatomy & Physiology#Maxilla|maxilla]] and extending further into the nasal cavity.

*The conchae divide the nasal cavity into nasal ducts or ''meatuses'', which branch out from a common nasal meatus which is adjacent to the nasal septum. There are three nasal meatuses which branch from the common nasal meatus: dorsal, middle and ventral:

- '''Dorsal nasal meatus''': the passage between the roof of the nasal cavity and the dorsal nasal concha

- '''Middle nasal meatus''': between the dorsal and ventral conchae, and communicates with the [[Paranasal sinuses - Anatomy & Physiology|paranasal sinuses]].

- '''Ventral nasal meatus''': the main pathway for airflow leading to the pharynx, and is positioned between the ventral nasal concha and the floor of the nasal cavity.

- '''Common nasal meatus''': the longitudinal space on either side of the nasal septum.

*The [[Paranasal sinuses - Anatomy & Physiology|Paranasal Sinuses]] are extensions of the nasal cavity.

==Function==

*In addition to [[Special Senses - Olfactory - Anatomy & Physiology|Olfaction,]] the function of the nasal cavity is to modify the incoming air before is is transported further down the respiratory tract.
*Air is warmed as it passes over the highly vascularised mucosal surfaces of the conchae, humidified by the evaporation from nasal secretion and cleaned as it contacts the secretion from mucus glands within the nasal cavity. The mucus secreted from the glands traps particles and cilia transport them down to the pharynx for swallowing, this process is known as the [[Respiratory Epithelium - Anatomy & Physiology#Mucociliary Escalator|Mucociliary Escalator]].
*The nasal cavity offers further protection via the Sneezing reflex .

==Species Differences==

*The nasal cavity in the '''sheep''' is highly vascularised, with any damage to the epithelium resulting in severe [[General Pathology - Haemorrhage|haemorrhage]].
*'''Cattle''' have a smaller nasal cavity compared to the horse.
*There are many variations to the entire [[Avian Respiration - Anatomy & Physiology|'''Avian''' respiratory tract]].
*The [[Respiration in Non-Homeotherms - Anatomy & Physiology|Respiratory Systems]] of non-Homeotherms]] are also very different to that of mammals.

==Links==

*[[Nasal Cavity - Pathology]]

==References==

*{{citation|initiallast = Dyce|initialfirst = K.M|2last = Sack|2first = W.O|finallast = Wensing|finalfirst = C.J.G|year = 2002|title = Textbook of Veterinary Anatomy|ed =3rd|city = Philadelphia|pub = Saunders}}

Nasal Cavity - Anatomy & Physiology

2008-08-15T09:20:01Z

Lwyacem:

{{toplink
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|linkpage =Cardiorespiratory System - Anatomy & Physiology
|linktext =Cardiorespiratory System
|maplink = Cardiorespiratory (Content Map) - Anatomy & Physiology
|pagetype =Anatomy
}}
 
[[Image:Nasal Cavities.jpg|thumb|right|300px|Nasal Cavities - Copyright David Bainbridge]]
==Introduction==

The respiratory tract begins with the ''nose'' which includes the external nose, internal nasal cavities and [[Paranasal sinuses - Anatomy & Physiology|paranasal sinuses]].
As well as being vital for transport of gases to the [[Cardiorespiratory System - Anatomy & Physiology#Lower Respiratory Tract|lower respiratory tract]], the nose is also the site for one of the special senses - [[Special Senses - Olfactory - Anatomy & Physiology|''Olfaction'']].

==Structure==

*The nose consists of the external nares with nasal [[Bones and Cartilage - Anatomy & Physiology#Structure and Function of Cartilage|cartilages]], the nasal cavity (including the nasal meatus and conchae), and the [[Paranasal sinuses - Anatomy & Physiology|paranasal sinuses]].

*The nasal cavity is essentially a tube with a wall established by several [[Skull and Facial Muscles - Anatomy & Physiology#Bones of the Skull|bones of the skull]]. The borders of the nasal cavity are as follows:

- ''Caudal'': cribrifrom plate of the [[Skull and Facial Muscles - Anatomy & Physiology#Ethmoid Bone (os ethmoidale)|ethmoid bone]]

- ''Ventral'': continuous with the nasopharynx

- ''Dorsal'': the maxilla and the palatine processes of the [[Skull and Facial Muscles - Anatomy & Physiology#Incisive Bone (os incisivium)|incisive bone]]

*Rostrally, the median septum is a continuation of the [[Skull and Facial Muscles - Anatomy & Physiology#Ethmoid Bone (os ethmoidale)|ethmoid bone]]. The median septum is made up of [[Bones and Cartilage - Anatomy & Physiology#Hyaline Cartilage|hyaline cartilage]], and divides the nasal cavity into left and right halves.

[[Image:DogHeadDissection.jpg|right|thumb|200px|The nasal cavity can be seen filled with conchae in this photograph of a canine head. ©Nottingham 2008]]

*The nasal cavity is occupied to a large extent by '''''Nasal conchae'''''. These are turbinate bones which project into the nasal cavity with the purpose of supporting the [[Special Senses - Olfactory - Anatomy & Physiology|olfactory]] mucus membranes and increasing the respiratory surface area, creating turbulence within the passing air. This helps to filtrate and warm or cool the air that passes through.

*The Conchae are [[Bones and Cartilage - Anatomy & Physiology#Types of Cartilage|cartilage]]nous or ossified scrolls which arise from the [[Skull and Facial Muscles - Anatomy & Physiology#Ethmoid Bone (os ethmoidale|''ethmoid bone'']]. They are covered with mucous membrane, under which is a layer of anastomosing blood vessels.
The nasal conchae are more complex in animals with a better sense of smell, as they increase the surface area of the [[Special Senses - Olfactory - Anatomy & Physiology|Olfactory]] region, further.

*There are dorsal and ventral conchae, the dorsal concha originating from the [[Skull and Facial Muscles - Anatomy & Physiology#Ethmoid Bone (os ethmoidale)|ethmoid bone]] and attaching to the maxilla, and the vental conchae originating from the [[Skull and Facial Muscles - Anatomy & Physiology#Maxilla|maxilla]] and extending further into the nasal cavity.

*The conchae divide the nasal cavity into nasal ducts or ''meatuses'', which branch out from a common nasal meatus which is adjacent to the nasal septum. There are three nasal meatuses which branch from the common nasal meatus: dorsal, middle and ventral:

- '''Dorsal nasal meatus''': the passage between the roof of the nasal cavity and the dorsal nasal concha

- '''Middle nasal meatus''': between the dorsal and ventral conchae, and communicates with the [[Paranasal sinuses - Anatomy & Physiology|paranasal sinuses]].

- '''Ventral nasal meatus''': the main pathway for airflow leading to the pharynx, and is positioned between the ventral nasal concha and the floor of the nasal cavity.

- '''Common nasal meatus''': the longitudinal space on either side of the nasal septum.

*The [[Paranasal sinuses - Anatomy & Physiology|Paranasal Sinuses]] are extensions of the nasal cavity.

==Function==

*In addition to [[Special Senses - Olfactory - Anatomy & Physiology|Olfaction,]] the function of the nasal cavity is to modify the incoming air before is is transported further down the respiratory tract.
*Air is warmed as it passes over the highly vascularised mucosal surfaces of the conchae, humidified by the evaporation from nasal secretion and cleaned as it contacts the secretion from mucus glands within the nasal cavity. The mucus secreted from the glands traps particles and cilia transport them down to the pharynx for swallowing, this process is known as the [[Respiratory Epithelium - Anatomy & Physiology#Mucociliary Escalator|Mucociliary Escalator]].
*The nasal cavity offers further protection via the Sneezing reflex .

==Species Differences==

*The nasal cavity in the '''sheep''' is highly vascularised, with any damage to the epithelium resulting in severe [[General Pathology - Haemorrhage|haemorrhage]].
*'''Cattle''' have a smaller nasal cavity compared to the horse.
*There are many variations to the entire [[Avian Respiration - Anatomy & Physiology|'''Avian''' respiratory tract]].
*The [[Fish Respiration - Anatomy & Physiology|Respiratory System of Fish]] is also very different to that of mammals.

==Links==

*[[Nasal Cavity - Pathology]]

==References==

*{{citation|initiallast = Dyce|initialfirst = K.M|2last = Sack|2first = W.O|finallast = Wensing|finalfirst = C.J.G|year = 2002|title = Textbook of Veterinary Anatomy|ed =3rd|city = Philadelphia|pub = Saunders}}

Paranasal Sinuses - Anatomy & Physiology

2008-08-15T09:19:40Z

Lwyacem:

Nasal Cavity - Anatomy & Physiology

2008-08-15T09:19:15Z

Lwyacem:

{{toplink
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[[Image:Nasal Cavities.jpg|thumb|right|300px|Nasal Cavities - Copyright David Bainbridge]]
==Introduction==

The respiratory tract begins with the ''nose'' which includes the external nose, internal nasal cavities and [[Paranasal sinuses - Anatomy & Physiology|paranasal sinuses]].
As well as being vital for transport of gases to the [[Cardiorespiratory System - Anatomy & Physiology#Lower Respiratory Tract|lower respiratory tract]], the nose is also the site for one of the special senses - [[Special Senses - Olfactory - Anatomy & Physiology|''Olfaction'']].

==Structure==

*The nose consists of the external nares with nasal [[Bones and Cartilage - Anatomy & Physiology#Structure and Function of Cartilage|cartilages]], the nasal cavity (including the nasal meatus and conchae), and the [[Paranasal sinuses - Anatomy & Physiology|paranasal sinuses]].

*The nasal cavity is essentially a tube with a wall established by several [[Skull and Facial Muscles - Anatomy & Physiology#Bones of the Skull|bones of the skull]]. The borders of the nasal cavity are as follows:

- ''Caudal'': cribrifrom plate of the [[Skull and Facial Muscles - Anatomy & Physiology#Ethmoid Bone (os ethmoidale)|ethmoid bone]]

- ''Ventral'': continuous with the nasopharynx

- ''Dorsal'': the maxilla and the palatine processes of the [[Skull and Facial Muscles - Anatomy & Physiology#Incisive Bone (os incisivium)|incisive bone]]

*Rostrally, the median septum is a continuation of the [[Skull and Facial Muscles - Anatomy & Physiology#Ethmoid Bone (os ethmoidale)|ethmoid bone]]. The median septum is made up of [[Bones and Cartilage - Anatomy & Physiology#Hyaline Cartilage|hyaline cartilage]], and divides the nasal cavity into left and right halves.

[[Image:DogHeadDissection.jpg|right|thumb|200px|The nasal cavity can be seen filled with conchae in this photograph of a canine head. ©Nottingham 2008]]

*The nasal cavity is occupied to a large extent by '''''Nasal conchae'''''. These are turbinate bones which project into the nasal cavity with the purpose of supporting the [[Special Senses - Olfactory - Anatomy & Physiology|olfactory]] mucus membranes and increasing the respiratory surface area, creating turbulence within the passing air. This helps to filtrate and warm or cool the air that passes through.

*The Conchae are [[Bones and Cartilage - Anatomy & Physiology#Types of Cartilage|cartilage]]nous or ossified scrolls which arise from the [[Skull and Facial Muscles - Anatomy & Physiology#Ethmoid Bone (os ethmoidale|''ethmoid bone'']]. They are covered with mucous membrane, under which is a layer of anastomosing blood vessels.
The nasal conchae are more complex in animals with a better sense of smell, as they increase the surface area of the [[Special Senses - Olfactory - Anatomy & Physiology|Olfactory]] region, further.

*There are dorsal and ventral conchae, the dorsal concha originating from the [[Skull and Facial Muscles - Anatomy & Physiology#Ethmoid Bone (os ethmoidale)|ethmoid bone]] and attaching to the maxilla, and the vental conchae originating from the [[Skull and Facial Muscles - Anatomy & Physiology#Maxilla|maxilla]] and extending further into the nasal cavity.

*The conchae divide the nasal cavity into nasal ducts or ''meatuses'', which branch out from a common nasal meatus which is adjacent to the nasal septum. There are three nasal meatuses which branch from the common nasal meatus: dorsal, middle and ventral:

- '''Dorsal nasal meatus''': the passage between the roof of the nasal cavity and the dorsal nasal concha

- '''Middle nasal meatus''': between the dorsal and ventral conchae, and communicates with the [[Paranasal sinuses - Anatomy & Physiology|paranasal sinuses]].

- '''Ventral nasal meatus''': the main pathway for airflow leading to the pharynx, and is positioned between the ventral nasal concha and the floor of the nasal cavity.

- '''Common nasal meatus''': the longitudinal space on either side of the nasal septum.

*The [[Paranasal sinuses - Anatomy & Physiology|Paranasal Sinuses]] are extensions of the nasal cavity.

==Function==

*In addition to [[Special Senses - Olfactory - Anatomy & Physiology|Olfaction,]] the function of the nasal cavity is to modify the incoming air before is is transported further down the respiratory tract.
*Air is warmed as it passes over the highly vascularised mucosal surfaces of the conchae, humidified by the evaporation from nasal secretion and cleaned as it contacts the secretion from mucus glands within the nasal cavity. The mucus secreted from the glands traps particles and cilia transport them down to the pharynx for swallowing, this process is known as the [[Respiratory Epithelium - Anatomy & Physiology#Mucociliary Escalator|Mucociliary Escalator]].
*The nasal cavity offers further protection via the Sneezing reflex .

==Species Differences==

*The nasal cavity in the '''sheep''' is highly vascularised, with any damage to the epithelium resulting in severe [[General Pathology - Haemorrhage|haemorrhage]].
*'''Cattle''' have a smaller nasal cavity compared to the horse.
*There are many variations to the entire [[Avian Respiration - Anatomy & Physiology|'''Avian''' respiratory tract]].

==Links==

*[[Nasal Cavity - Pathology]]
*The [[Avian Respiration - Anatomy & Physiology|Avian respiratory tract]] has some fundamental differences to that of mammals.
*The [[Fish Respiration - Anatomy & Physiology|Respiratory System of Fish]] is also very different to that of mammals.

==References==

*{{citation|initiallast = Dyce|initialfirst = K.M|2last = Sack|2first = W.O|finallast = Wensing|finalfirst = C.J.G|year = 2002|title = Textbook of Veterinary Anatomy|ed =3rd|city = Philadelphia|pub = Saunders}}

Lungs - Anatomy & Physiology

2008-08-15T09:18:19Z

Lwyacem: /* Species Differences */

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[[Image:Doglungdeflated.jpg|right|thumb|250px|©RVC 2008]]

==Introduction==

[[Image:Doglunginflated.jpg|right|thumb|250px|©RVC 2008]]
The lungs are the site for [[Gas Exchange - Anatomy & Physiology|gaseous exchange]], and are situated within the thoracic cavity. They occupy approximatley 5% of the body volume in mammals when relaxed, but generally have no fixed size or shape since their volume is constantly changing with the processes of [[Ventilation - Anatomy & Physiology#Inspiration|inspiration]] and [[Ventilation - Anatomy & Physiology#Expiration|expiration]].

The lungs, along with the [[Larynx - Anatomy & Physiology|larynx]] and [[Trachea - Anatomy & Physiology|trachea]], develop from a ventral respiratory tract. After separation from the developing [[Oesophagus - Anatomy & Physiology|oesophagus]], two lung buds develop, which undergo divisions as they grow, forming the beginnings of the [[Bronchi and bronchioles - Anatomy & Physiology|bronchial]] tree. This process is not completed by [[Parturition - Normal Parturition - Anatomy & Physiology|parturition]].

==Structure==

*The left and right lungs lie within their [[Pleural cavity and membranes - Anatomy & Physiology|pleural]] sac and are only attached by their roots, to the [[Mediastinum - Anatomy & Physiology|mediastinum]], so they are fairly free within the thoracic cavity.
*The right lung is always larger than the left, due to the positioning of the [[Heart - Anatomy & Physiology|heart]]. The apex of the lungs is their cranial point.
*In most species the lungs are divided into lobes by the [[Bronchi and bronchioles - Anatomy & Physiology|bronchial]] tree:
**'''Left Lung''' = Cranial and Caudal lobes.
**'''Right Lung''' = Cranial, Caudal, Middle and Accessory lobes. The cranial lobe is further divided by an external fissure.[[Image:Routeofairthroughrespiratorysystem.jpg|right|thumb|200px|'''Schematic Diagram showing the route air takes through the respiratory system''']]
*The bulk of the lung consists of [[Bronchi and bronchioles - Anatomy & Physiology|bronchi]], [[Anatomy of Blood Vessels - Anatomy & Physiology|blood vessels]] and connective tissue. The terminal [[Bronchi and bronchioles - Anatomy & Physiology|bronchioles]] have alveoli scattered along their length, and are continued by alveolar ducts, alveolar sacs and finally alveoli.
**'''Alveolar Ducts''': These have alveoli which open on all of it's sides, they have no 'walls' as such. Openings to individual alveoli are guarded by [[Muscles - Anatomy & Physiology#Smooth Muscle|smooth muscle]].
**'''Alveolar Sacs''': These are rotunda-like areas on the end of each alveolar ducts which are usually present in clusters.
**'''Alveoli''': These are minute, polygonal chambers, whose diameter changes with the processes of [[Ventilation - Anatomy & Physiology#Inspiration|inspiration]] and [[Ventilation - Anatomy & Physiology#Expiration|expiration]], and varies by species. The wall of the alveoli is extremely thin, consisting of 2 irregular layers of epithelial sheets, 'sandwiching' a network of capillaries. Thus the ''Blood-Gas Barrier'' is just a single basal lamina - ideal for [[Gas Exchange - Anatomy & Physiology|gaseous exchange]]. The alveolar interstitium is formed from connective tissue fibres and cells, which include collagen fibrils and elastin fibres.

==Function==

*[[Gas Exchange - Anatomy & Physiology|Gas Exchange]]

==Vasculature==

*The '''Pulmonary Arteries''' follow the bronchi while the '''Pulmonary veins''' sometimes run separately.
*'''Bronchial arteries''' from the Aorta supply the bronchi, and '''Bronchial veins''' may drain this blood to the [[Structure of the Heart - Anatomy & Physiology#Right Atrium|right atrium]] via the '''Azygous Vein'''. More often the blood from the bronchi drains directly to the [[Structure of the Heart - Anatomy & Physiology#Left Atrium|left atrium]].

==Innervation==

* Nervous supply to the lung is via the '''Pulmonary Plexus''' within the [[Mediastinum - Anatomy & Physiology|mediastinum]].
*The Pulmonary Plexus consists of Sympathetic Fibres largely from the Stellate Ganglion, and Parasympathetic Fibres from the [[Nervous System - CNS - Anatomy & Physiology#Innervation - Cranial Nerves|Vagus nerve]].

==Lymphatics==

* Lymph drains to the '''Tracheobronchial''' and '''Mediastinal''' [[Lymph Nodes - Anatomy & Physiology|lymph nodes]].

==Histology==

<center><gallery>
Image:Lungadultlowmag.jpg|'''Lung (adult)'''©RVC 2008
Image:SEMAdultSheepLung.jpg|'''SEM of Adult Sheep Lung'''©RVC 2008
Image:Bronchuslowpower.jpg|'''Bronchus'''©RVC 2008
Image:Bronchuslowpower2.jpg|'''Bronchus'''©RVC 2008
Image:Alveoli.jpg|'''Alveoli'''©RVC 2008
Image:Alveoli2.jpg|'''Alveoli'''©RVC 2008
</gallery></center>

==Species Differences==

* Externally the lungs of the '''Horse''' show almost no lobation. Internally the right lung of the horse lacks a Middle Lobe.
*The lungs of '''Ruminants''' and '''Pigs''' are obviously lobed.
*The fissures between lobes (''Interlobar fissures'') are deeper in the dog and cat lung compared to other species.
*[[Avian Respiration - Anatomy & Physiology|Avian Respiration]] has many fundamental differences to mammalian respiration.
*The [[Fish Respiration - Anatomy & Physiology|Respiratory System of Fish]] is also very different to that of mammals.

==Links==

[[Lungs - Pathology]]

==References==

*{{citation|initiallast = Dyce|initialfirst = K.M|2last = Sack|2first = W.O|finallast = Wensing|finalfirst = C.J.G|year = 2002|title = Textbook of Veterinary Anatomy|ed =3rd|city = Philadelphia|pub = Saunders}}

Avian Respiration - Anatomy & Physiology

2008-08-15T09:16:42Z

Lwyacem: /* Avian Gas Exchange */

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==Introduction==

The avian respiratory system contains some fundamental differences to the mammalian system.

==Avian Nasopharynx and Oropharynx==

*The nostrils of the bird, which lead into the [[Nasal cavity - Anatomy & Physiology|nasal cavity]], may have a flap of horn to protect them, known as the ''Operculum''.
*The Oral Cavity and the Nasal Cavity of the bird are interconnecting via a slit in the [[Hard Palate - Anatomy & Physiology|hard palate]] called the ''Choana''. Birds lack a [[Soft Palate - Anatomy & Physiology|soft palate]].
[[Image:Avianheadsaggitalsection.jpg|right|thumb|350px|©Nottingham 2008 ''Saggital Section of an Avian skull showing the conchae.]]
*There are Rostral, Middle and Caudal Conchae arising from the lateral wall, filling part of the [[Nasal cavity - Anatomy & Physiology|nasal cavity]].
**Rostral Conchae - Vestibular Region - lined with Stratified Squamous Epithelium
**Middle Conchae - Respiratory Region - lined with [[Respiratory Epithelium - Anatomy & Physiology|Respiratory Epithelium]].
**Caudal Conchae - [[Special Senses - Olfactory - Anatomy & Physiology|Olfactory]] Region - lined with [[Special Senses - Olfactory - Anatomy & Physiology|olfactory]] epithelium.
*The '''Infraorbital Sinus''' is a triangular cavity under the skin, rostroventral to the eye.
*Some marine birds have a ''Salt Gland'' (nasal gland) which excretes sodium.

==Avian Larynx==
*The [[Larynx - Anatomy & Physiology|larynx]] is on the floor of the [[Oral Cavity - Oropharynx - Anatomy & Physiology|oropharynx]] supported by '''Cricoid''' and paried '''Arytenoid''' Cartilages which are different in structure to those in mammals.
*There is no [[Epiglottis|Epiglottis.]]
*There are no vocal folds - birds vocalise using a [[Syrinx - Anatomy & Physiology|syrinx]].

==Avian Trachea==
*The avian [[Trachea - Anatomy & Physiology|trachea]] is composed of tightly stacked [[Bones and Cartilage - Anatomy & Physiology|cartilages]] which are shaped similarly to signet rings. These are complete with no dorsal space as in the mammalian [[Trachea - Anatomy & Physiology|trachea]]. They overlap considerably.
*The trachea can be palpated on the right side of the neck; it runs alongside the [[Oesophagus - Anatomy & Physiology|oesophagus]].
*The trachea is lined with [[Respiratory Epithelium - Anatomy & Physiology|Respiratory Epithelium]].
*The trachea bifurcates into two main [[Bronchi and bronchioles - Anatomy & Physiology|bronchi]] as in mammals. The [[Syrinx - Anatomy & Physiology|syrinx]] is formed by this terminal part of the trachea.

==Avian Lungs==
*Avian [[Lungs - Anatomy & Physiology|lungs]] are relatively small, with a bird's lungs being approximately 50% as large as the lung of a mammal of a similar size. The lungs are unlobed and do not have the capacity to expand.
*The lungs are positioned in the craniodorsal region of the body, and are deeply indented by both the thoracic [[Spinal Column - Anatomy & Physiology#Vertebrae and Joints|vertebrae]] and [[Ribs and Sternum - Anatomy & Physiology|ribs]].
*Birds do not have a [[Pleural cavity and membranes|pleural cavity]] as the lungs do not expand, thus the membranes are not necessary.

==Air Sacs==
*Birds lack a [[Diaphragm - Anatomy & Physiology|diaphragm]], and their thoracic and abdominal cavities are continuous.
*The bird has a number of thin walled, easily distensible '''Air Sacs''' which can extend to approximatley 10x the volume of the [[Lungs - Anatomy & Physiology|lungs]]. These are present within body cavities, and extend into some specific [[Bones and Cartilage - Anatomy & Physiology|bones]], to take the place of [[Bone Marrow - Anatomy & Physiology|bone marrow]]. This has the added function of reducing the weight of the bone, as they are essentially filled with air.
*The chicken has 8 air sacs:
**'''Cervical''' - this extends within the cervical and thoracic [[Spinal Column - Anatomy & Physiology#Vertebrae and Joints|vertebrae]].
**'''Clavicular''' - lies within the thoracic inlet, surrounding the [[Heart - Anatomy & Physiology|heart]], and within the humerus in the [[Forelimb - Anatomy & Physiology|forelimb]].
**'''Cranial Thoracic''' (x2) - these are ventral to the [[Lungs - Anatomy & Physiology|lungs]].
**'''Caudal Thoracic''' (x2) - located between the body wall and the thoracic air sacs.
**'''Abdominal''' (x2) - these are the largest air sacs and fill the caudodorsal region of the abdomen, in contact with [[Small Intestine - Anatomy & Physiology|small]] and [[Large Intestine - Anatomy & Physiology|large intestines]], [[Kidney Basic Anatomy & Physiology|kidneys]] and [[Reproductive System|reproductive]] organs. In addition these airsacs utilise space within the acetabulum and synsacrum.
*The Cervical, Clavicular and Cranial Thoracic air sacs form one functional group - '''Cranial''', with the Caudal Thoracic and Abdominal Air sacs forming another, '''Caudal''' functional group.
*The air sacs have a vital role in [[Ventilation - Anatomy & Physiology|ventilation]], but do not have the capacity for [[Gas Exchange - Anatomy & Physiology|gaseous exchange]].

==Avian Ventilation==
*[[Ventilation - Anatomy & Physiology|Ventilation]] in birds is strikingly different to that of mammals in that air flows through the lungs in the same direction during both [[Ventilation - Anatomy & Physiology#Inspiration|inspiration]] and [[Ventilation - Anatomy & Physiology#Expiration|expiration]]. In addition, both the intaking of air and the expelling of air are active processes, requiring [[Muscles - Anatomy & Physiology|muscle]] contraction.
*During Inspiration, the [[Ribs and Sternum - Anatomy & Physiology|ribs]] are drawn forwards and the [[Ribs and Sternum - Anatomy & Physiology|sternum]] lowered, the Caudal air sacs receiving fresh air.
*Simultaneously, the Cranial air sacs recieve air which was inhaled at the previous inhalation which is drawn from the lungs, this air has lost much of it's oxygen content.
*During Expiration, the [[Ribs and Sternum - Anatomy & Physiology|sternum]] is drawn caudal and dorsal, the air sacs are compressed, air from the caudal air sac passes through the [[Lungs - Anatomy & Physiology|lungs]], while the air in the cranial air sac leaves via the [[Trachea - Anatomy & Physiology|trachea]].
*Thus oxygenated air passes through the lungs on both [[Ventilation - Anatomy & Physiology#Inspiration|inspiration]] and [[Ventilation - Anatomy & Physiology#Expiration|expiration]].

==Avian Gas Exchange==
*One '''Primary Bronchi''' from the [[Trachea - Anatomy & Physiology|trachea]] enters each lung, narrowing as it travels through, and communicates with the '''Abdominal Air Sac'''. This bronchi gives off branches as it travels through the lung, known as '''Secondary Bronchi'''. Each of these gives off a further 400-500 '''Parabronchi''' in the walls of which, [[Gas Exchange - Anatomy & Physiology|gaseous exchange]] takes place.
*Avian Gas exchange takes place not in alveoli, as in mammals, but within '''Air Capillaries''' which are extensions of the parabronchial lumen. They are an interconnecting network of loops, and closely intertwine with Blood Capillaries.
*The Air Capillaries and Blood Capillaries are arranged so that flow is ''crosscurrent''. This makes the [[Gas Exchange - Anatomy & Physiology|gaseous exchange]] which occurs from one to the other extremely efficient.

==Links==

==References==

*{{citation|initiallast = Dyce|initialfirst = K.M|2last = Sack|2first = W.O|finallast = Wensing|finalfirst = C.J.G|year = 2002|title = Textbook of Veterinary Anatomy|ed =3rd|city = Philadelphia|pub = Saunders}}
*{{citation|initiallast = Sjaastad|initialfirst = O.V|2last = Hove|2first = K|finallast = Sand|finalfirst = O|year = 2004|title = Physiology of Domestic Animals|city = Oslo|pub = Scandinavian Veterinary Press}}

Trachea - Anatomy & Physiology

2008-08-15T09:15:59Z

Lwyacem: /* Histology */

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[[Image:TracheaRatlowpower.jpg|right|thumb|400px|©RVC 2008]]

==Introduction==

The trachea is the tube linking the cricoid [[Bones and Cartilage - Anatomy & Physiology#Types of Cartilage|cartilage]] of the [[Larynx - Anatomy & Physiology |larynx]] to the [[Bronchi and bronchioles - Anatomy & Physiology|bronchi]], forming part of the conducting system which transports air from the external environment to the [[Lungs - Anatomy & Physiology|lungs]]. The [[Oesophagus - Anatomy & Physiology|oesophagus]] lies dorsally to the trachea.
The cervical part of the trachea lies generally in the median position, although this varies slightly depending on the position of the head.
The thoracic part of the trachea crosses the aortic arch, thus it's positioning is moved slightly to the right at this level.

The trachea bifurcates to form the two [[Bronchi and bronchioles - Anatomy & Physiology|bronchi]] at the level of the 4th-6th inter[[Ribs and Sternum - Anatomy & Physiology#Costae|costal]] space.

==Structure==

*The trachea contains numerous rings of [[Bones and Cartilage - Anatomy & Physiology#Hyaline Cartilage|hyaline cartilage]] which are C-shaped, being dorsally incomplete, connected to eachother by elastic connective tissue. The ends of the incomplete rings are joined by smooth muscle - ''Trachealis'' muscle.
**The structural conformation of the trachea prevents collapse due to traction forces, whilst allowing it to adjust in length and diameter as the neck moves and the [[Diaphragm - Anatomy & Physiology|diaphragm]] contracts.
*The trachea's walls are made up of a number of layers: Inner Mucosa, Fibrocartilaginous middle layer, and and adventitia (in the neck) or serosa (in the thorax).
*The inner mucosa contains glands which produce mucus. This mucus traps debris and is constantly moved upwards towards the [[Oral Cavity - Oropharynx - Anatomy & Physiology|oropharynx]] where it is swallowed. This mechanism is known as the [[Respiratory Epithelium - Anatomy & Physiology#Mucociliary Escalator|''Muco-Ciliary escalator'']].

==Function==

*Transporting air for respiration from the [[Larynx - Anatomy & Physiology|larynx]] to the [[Bronchi and bronchioles - Anatomy & Physiology|bronchi]].

==Histology==

<center><gallery>
Image:TrachealWallRAT.jpg|'''Tracheal Wall (Rat)'''©RVC 2008
Image:TrachealWallLiningRAT.jpg|'''Epithelial Lining of the Tracheal Wall (Rat)'''©RVC 2008
Image:TrachealWallstainedforelasticfibresCAT.jpg|'''Tracheal Wall stained for elastic fibres (Cat).'''©RVC 2008

</gallery></center>

==Species Differences==

*In the '''Dog and Cat''' the C-Shaped rings are joined by muscle which is placed externally, rather than internally as is normal for the other species.
*In [[Avian Respiration - Anatomy & Physiology|'''avian]] species''' the trachea is composed of tightly stacked rings of [[Bones and Cartilage - Anatomy & Physiology#Types of Cartilage|cartilage]], which are complete with no dorsal space. They overlap considerably.

==Links==

*[[Trachea - Pathology]]

*[[Syrinx - Anatomy & Physiology|The Syrinx- avian vocalisation]]

==References==

*{{citation|initiallast = Dyce|initialfirst = K.M|2last = Sack|2first = W.O|finallast = Wensing|finalfirst = C.J.G|year = 2002|title = Textbook of Veterinary Anatomy|ed =3rd|city = Philadelphia|pub = Saunders}}

Trachea - Anatomy & Physiology

2008-08-15T09:15:43Z

Lwyacem: /* Histology */

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[[Image:TracheaRatlowpower.jpg|right|thumb|400px|©RVC 2008]]

==Introduction==

The trachea is the tube linking the cricoid [[Bones and Cartilage - Anatomy & Physiology#Types of Cartilage|cartilage]] of the [[Larynx - Anatomy & Physiology |larynx]] to the [[Bronchi and bronchioles - Anatomy & Physiology|bronchi]], forming part of the conducting system which transports air from the external environment to the [[Lungs - Anatomy & Physiology|lungs]]. The [[Oesophagus - Anatomy & Physiology|oesophagus]] lies dorsally to the trachea.
The cervical part of the trachea lies generally in the median position, although this varies slightly depending on the position of the head.
The thoracic part of the trachea crosses the aortic arch, thus it's positioning is moved slightly to the right at this level.

The trachea bifurcates to form the two [[Bronchi and bronchioles - Anatomy & Physiology|bronchi]] at the level of the 4th-6th inter[[Ribs and Sternum - Anatomy & Physiology#Costae|costal]] space.

==Structure==

*The trachea contains numerous rings of [[Bones and Cartilage - Anatomy & Physiology#Hyaline Cartilage|hyaline cartilage]] which are C-shaped, being dorsally incomplete, connected to eachother by elastic connective tissue. The ends of the incomplete rings are joined by smooth muscle - ''Trachealis'' muscle.
**The structural conformation of the trachea prevents collapse due to traction forces, whilst allowing it to adjust in length and diameter as the neck moves and the [[Diaphragm - Anatomy & Physiology|diaphragm]] contracts.
*The trachea's walls are made up of a number of layers: Inner Mucosa, Fibrocartilaginous middle layer, and and adventitia (in the neck) or serosa (in the thorax).
*The inner mucosa contains glands which produce mucus. This mucus traps debris and is constantly moved upwards towards the [[Oral Cavity - Oropharynx - Anatomy & Physiology|oropharynx]] where it is swallowed. This mechanism is known as the [[Respiratory Epithelium - Anatomy & Physiology#Mucociliary Escalator|''Muco-Ciliary escalator'']].

==Function==

*Transporting air for respiration from the [[Larynx - Anatomy & Physiology|larynx]] to the [[Bronchi and bronchioles - Anatomy & Physiology|bronchi]].

==Histology==

<center><gallery>
Image:TrachealWallRAT.jpg|'''Tracheal Wall (Rat)'''©RVC 2008
Image:TrachealWallLiningRAT.jpg|'''Epithelial Lining of the Tracheal Wall (Rat)'''©RVC 2008
Image:TrachealWallstainedforelasticfibresCAT.jpg|'''Tracheal Wall stained for elastic fibres (Cat).'''©RVC 2008
Image:Trachea epithelium.jpg|'''Tracheal Wall stained for elastic fibres (Cat).'''©RVC 2008
</gallery></center>

==Species Differences==

*In the '''Dog and Cat''' the C-Shaped rings are joined by muscle which is placed externally, rather than internally as is normal for the other species.
*In [[Avian Respiration - Anatomy & Physiology|'''avian]] species''' the trachea is composed of tightly stacked rings of [[Bones and Cartilage - Anatomy & Physiology#Types of Cartilage|cartilage]], which are complete with no dorsal space. They overlap considerably.

==Links==

*[[Trachea - Pathology]]

*[[Syrinx - Anatomy & Physiology|The Syrinx- avian vocalisation]]

==References==

*{{citation|initiallast = Dyce|initialfirst = K.M|2last = Sack|2first = W.O|finallast = Wensing|finalfirst = C.J.G|year = 2002|title = Textbook of Veterinary Anatomy|ed =3rd|city = Philadelphia|pub = Saunders}}

Ventilation - Anatomy & Physiology

2008-08-15T09:14:56Z

Lwyacem: /* Inspiration */

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==Introduction==

Ventilation is the movement of air into and out of the [[Lungs - Anatomy & Physiology|lungs]]. Air moves from high pressure to low pressure with the rate of flow being proportional to the pressure difference. As environmental pressure is generally constant, the [[Cardiorespiratory System - Anatomy & Physiology|respiratory system]] must change it's internal pressure to maintain air flow.

The lungs are not fixed to the thoracic wall but follow the changing volume of the thoracic cavity thanks to the [[Pleural cavity and membranes - Anatomy & Physiology#Pleural Membranes|Pleura]].

==Inspiration==

*During Inspiration, the pressure within the [[Pleural cavity and membranes - Anatomy & Physiology|Pleural Cavity]] drops to less that the pressure of the external environment.
*This is achieved by increasing the [[Lungs - Anatomy & Physiology|lung]] volume, brought about by the Inspiratory Muscles:
**[[Diaphragm - Anatomy & Physiology|Diaphragm]] - contracts - causing the dome to flatten and moe caudally.
**[[Ribs and Sternum - Anatomy & Physiology#Thoracic Musculature|Intercostal muscles]] - External Intercostal Muscles contract - causing the [[Ribs and Sternum - Anatomy & Physiology|ribs]] to be pulled outwards cranially.

==Expiration==
During Expiration, the pressure within the [[Pleural cavity and membranes - Anatomy & Physiology|Pleural Cavity]] increases to greater than that of the external environment, in orfer to expel air from the [[Lungs - Anatomy & Physiology|lungs]]. This is achieved by decreasing the lung volume, caused by relaxation of Inspiratory Muscles:
**Dome of the [[Diaphragm - Anatomy & Physiology|Diaphragm]] is pushed back by the intrathoracic pressure.
**[[Ribs and Sternum - Anatomy & Physiology|Ribs]] recoil back to their original position.

==Species Differences==

*[[Avian Respiration - Anatomy & Physiology|Avian Ventilation]] is different to mammalian ventilation, requiring different muscles.

==Links==

==References==
*{{citation|initiallast = Budras|initialfirst = K.D|2last = McCarthy|2first = P.H|3last = Fricke|3first = W|finallast = Richter|finalfirst = R|year = 2002|title = Anatomy of the Dog|ed =4th|city = Hannover|pub = Schlutersche GmbH & Co. KG, Verlag und Druckerei}}

Ventilation - Anatomy & Physiology

2008-08-15T09:14:24Z

Lwyacem: /* Introduction */

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==Introduction==

Ventilation is the movement of air into and out of the [[Lungs - Anatomy & Physiology|lungs]]. Air moves from high pressure to low pressure with the rate of flow being proportional to the pressure difference. As environmental pressure is generally constant, the [[Cardiorespiratory System - Anatomy & Physiology|respiratory system]] must change it's internal pressure to maintain air flow.

The lungs are not fixed to the thoracic wall but follow the changing volume of the thoracic cavity thanks to the [[Pleural cavity and membranes - Anatomy & Physiology#Pleural Membranes|Pleura]].

==Inspiration==

*During Inspiration, the pressure within the [[Pleural cavity and membranes - Anatomy & Physiology|Pleural Cavity]] drops to less that the pressure of the external environment.
*This is achieved by increasing the [[Lungs - Anatomy & Physiology|lung]] volume, brought about by the Inspiratory Muscles:
**[[Diaphragm - Anatomy & Physiology|Diaphragm]] - contracts - causing the dome to flatten and moe caudally.
**[[Ribs and Sternum - Anatomy & Physiology#Thoracic Musculature|Intercostal muscles]] - [[Ribs and Sternum - Anatomy & Physiology#Thoracic Musculature|External Intercostal muscles]] contract - causing the [[Ribs and Sternum - Anatomy & Physiology|ribs]] to be pulled outwards cranially.

==Expiration==
During Expiration, the pressure within the [[Pleural cavity and membranes - Anatomy & Physiology|Pleural Cavity]] increases to greater than that of the external environment, in orfer to expel air from the [[Lungs - Anatomy & Physiology|lungs]]. This is achieved by decreasing the lung volume, caused by relaxation of Inspiratory Muscles:
**Dome of the [[Diaphragm - Anatomy & Physiology|Diaphragm]] is pushed back by the intrathoracic pressure.
**[[Ribs and Sternum - Anatomy & Physiology|Ribs]] recoil back to their original position.

==Species Differences==

*[[Avian Respiration - Anatomy & Physiology|Avian Ventilation]] is different to mammalian ventilation, requiring different muscles.

==Links==

==References==
*{{citation|initiallast = Budras|initialfirst = K.D|2last = McCarthy|2first = P.H|3last = Fricke|3first = W|finallast = Richter|finalfirst = R|year = 2002|title = Anatomy of the Dog|ed =4th|city = Hannover|pub = Schlutersche GmbH & Co. KG, Verlag und Druckerei}}