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Avian Respiration - Anatomy & Physiology (view source)
Revision as of 12:26, 14 August 2008
, 12:26, 14 August 2008→Air Sacs
**'''Cervical''' - this extends within the cervical and thoracic vertebrae.
**'''Cervical''' - this extends within the cervical and thoracic vertebrae.
**'''Clavicular''' - lies within the thoracic inlet, surrounding the heart, and within the humerus in the [[Forelimb - Anatomy & Physiology|forelimb]].
**'''Clavicular''' - lies within the thoracic inlet, surrounding the heart, and within the humerus in the [[Forelimb - Anatomy & Physiology|forelimb]].
**'''Cranial Thoracic''' (x2) - are ventral to the lungs.
**'''Cranial Thoracic''' (x2) - these are ventral to the lungs.
**'''Caudal Thoracic''' (x2) - between the body wall and the thoracic air sacs
**'''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 intestines, kidneys and genital organs. In addition they enter the acetabulum and synsacrum.
**'''Abdominal''' (x2) - these are the largest air sacs and fill the caudodorsal region of the abdomen, in contact with intestines, kidneys and genital 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, but do not have the capacity for gaseous exchange.
==Avian Ventilation==
*Ventilation is birds is strikingly different to that of mammals in that air flows through the lungs in the same direction during both inspiration and expiration.
*Ventilation is birds is strikingly different to that of mammals in that air flows through the lungs in the same direction during both inspiration and expiration. In addition, both the intaking of air and the expelling of air are active processes, requiring muscle contraction.
*During Inspiration, the ribs are drawn forwards and the sternum lowered, the Caudal Sacs recieving 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 air sacs are compressed, air from the caudal sac passes through the lungs, while the air in the Cranial Sac leaves via the trachea.
==Avian Gas Exchange==
*One '''Primary Bronchi''' from the 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, gaseous exchange takes place.
*One '''Primary Bronchi''' from the 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, 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.
*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 gaseous exchange which occurs from one to the other extremely efficient.
*The Air Capillaries and Blood Capillaries are arranged so that flow is ''crosscurrent''. This makes the gaseous exchange which occurs from one to the other extremely efficient.
==Links==
==Links==