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Rumen - Anatomy & Physiology (view source)
Revision as of 23:14, 25 August 2008
, 23:14, 25 August 2008New page: {{toplink |backcolour =BCED91 |linkpage =Alimentary - Anatomy & Physiology |linktext =Alimentary System |maplink = Alimentary (Concept Map)- Anatomy & Physiology |pagetype =Anatomy |subtex...
{{toplink
|backcolour =BCED91
|linkpage =Alimentary - Anatomy & Physiology
|linktext =Alimentary System
|maplink = Alimentary (Concept Map)- Anatomy & Physiology
|pagetype =Anatomy
|subtext1=STOMACH AND ABOMASUM
|sublik1=Stomach and Abomasum - Anatomy & Physiology
}}
<br>
[[Image:Rumen Topography Sheep.jpg|thumb|right|150px|Rumen Topography (Sheep) - Copyright RVC 2008]]
==Introduction==
The rumen is the first chamber of the ruminant stomach. It is the largest chamber and has regular contractions to move food around for digestion, eliminate gases through [[Eructation - Anatomy & Physiology|eructation]] and send food particles back to the mouth for [[Mastication|remastication]].
The rumen breaks down food particles through mechanical digestion and fermentation with the help of symbiotic microbes. [[Volatile Fatty Acids - Anatomy & Physioogy|Volatile fatty acids]] are the main product of ruminant digestion.
==Structure==
[[Image:Rumen Anatomy Sheep.jpg|thumb|right|150px|Rumen Anatomy (Sheep) - Copyright RVC 2008]]
*Grooves correspond with thickened smooth muscle pillars on the inside of the rumen
**Ruminal pillars divide the dorsal and ventral ruminal sacs
**Coronary pillars divide the caudal blind sacs
**Cranial pillar divides the dorsal and cranial sacs
*Covered by greater omentum
*38-40°C
*Anaerobic
*pH 6.7
*Buffered
*Large holding capacity
*Water intake lowers the ruminal temperature so bacteria are tolerant to temperature changes towards the lower end of the scale
*Objects are often lodged in the rumino-reticular fold. When the rumen contracts, the object can be pushed through the [[The Reticulum|reticulum]] wall into the [[Structure of the Heart - Anatomy & Physiology#Pericardium|pericardium]] and [[Heart - Anatomy & Physiology|heart]].
*Laterally compressed
*Extends from the cardia at the level of the 8th rib to the pelvic inlet
*Serosa covers the entire rumen except dorsally where the rumen attaches to the abdominal roof allowing more freedom for ruminal movement and expansion
*Ruminal contractions can be felt for in the left paralumbar fossa
*1-2 contractions should be felt per minute
*Opening at the cardia into both the rumen and [[The Reticulum|reticulum]] is called the reticuluar groove (see [[Oesophageal groove|oesophageal groove]])
==Function==
*Waste removal
*Simpler products of digestion are assilimated directly, others continue down the digestive tract for further digestion
*Mixes food
*Moves food forwards through the stomach chambers
*Sensors in the rumen can determine the courseness of the food. Course, tough feed needs stronger and more frequent ruminal contractions.
*Vagus nerve ([[Nervous System - CNS - Anatomy & Physiology#Innervation - Cranial Nerves|CN X]]) is needed for control of stomach movements
*Reflex control through sensory receptors in the medulla
*See [[Rumination - Anatomy & Physiology|rumination]]
*See [[Eructation - Anatomy & Physiology|eructation]]
==Ruminoreticular contraction==
[[Image:Contractions of the ruminoreticulum diagram.jpg|thumb|right|150px|Diagram of the contractions of the ruminoreticulum - Copyright RVC 2008]]
*Primary mixes food
**Mixing cycle of ruminoreticulum
**2 contractions of the [[The Reticulum|reticulum]] (2nd most powerful) which continues over the rumen
**Ingesta flows from the [[The Reticulum|reticulum]] to cranial ruminal sac to [[The Reticulum|reticulum]] (or ventral sac)
**Every 60 seconds
*Secondary lets gas out
**See [[Eructation - Anatomy & Physiology|eructation]]
**Ingesta flows from ventral blind sac to dorsal blind sac to dorsal sac ([[Eructation - Anatomy & Physiology|eructation]]) to ventral sac
==Vasculature==
*Cranial mesenteric artery
*Celiac artery
*Right and left ruminal arteries
==Innervation==
*Dorsal vagus ([[Nervous System - CNS - Anatomy & Physiology#Innervation - Cranial Nerves|CN X]]) (most important)
*Ventral vagus ([[Nervous System - CNS - Anatomy & Physiology#Innervation - Cranial Nerves|CN X]])
==Lymphatics==
*Caudal mediastinal lymph node enlargement put pressure on the dorsal vagus effecting ruminal contractions
*Numerous small lymph nodes are scattered in the ruminal grooves
*The lymph drains to larger atrial nodes between the cardia and [[The Omasum|omasum]], then to the cistera chyli
==Histology==
[[Image:Rumen Histology Sheep.jpg|thumb|right|150px|Rumen Histology (Sheep) - Copyright RVC 2008]]
*Keratinised stratified squamous epithelium
*Non-glandular
*No lamina muscularis
*2 thick layers of tunica muscularis- inner circular and outer longitudinal
*Interior surface of the rumen forms numerous papillae
**Papillae can be long and foliate
**Papillae can be short and pointed
**Up to 6mm in length
**Animals fed on rough grass or in the dry season have longer papillae
**Animals fed on digestible feed or in the wet season have shorter papillae (1-2mm in length)
**Fewer dorsally
**Increase surface area for [[Volatile Fatty Acids - Anatomy & Physioogy|volatile fatty acid]] absorption
*The upper keratinised layer of papillae protects against abrasion
*The deeper layers of papillae metabolise the [[Volatile Fatty Acids - Anatomy & Physioogy|volatile fatty acids]]
==Rumen Microbes==
*Have a variety of microbes that can utilise many substrates
*Dominance of different bacterial species depends on pH. Ergo, microbial populations are not constant
*Microbes digest cellulose and hemi-cellulose
*Microbes provide a source of all amino acids
*Microbes synthesise vitamins (especially the B vitamins)
'''Rumen Microbial Population'''
*Bacteria
**Over 2000 species
**99.5% obligate anaerobes
*Protozoa
**Large
**Unicellular organisms
**Prey on bacteria
**Numbers affected by diet
*Fungi
**Digest fibre
**Numbers present usually low
'''Common Rumen Microbes'''
{| style="width:75%; height:200px" border="1"
!'''Species'''
!'''Type'''
!'''pH'''
|-
| '''Ruminococcus flavefauens'''
| Fibre
| 6.15
|-
| '''Fibrobacter succinogens'''
| Fibre
| 6
|-
| '''Megashpaera eisdeni'''
| Lactate user
| 4.9
|-
| '''Streptococcus bovis'''
| Lactate producer
| 4.55
|}
==Species Differences==
===Small Ruminats===
*Sheep and goats have a larger ventral ruminal sac than dorsal ruminal sac
*Cranial mesenteric artery and celiac artery come off the same root
===Bovine===
*Cranial mesenteric artery and celiac artery are close in the cow
*Dairy cows have a rumen pH of 5.5 due to more digestible feed
==Links==
[[The Reticulum|The Reticulum - Anatomy & Physiology]]
[[The Omasum|The Omasum - Anatomy & Physiology]]
[[The Abomasum|The Abomasum- Anatomy & Physiology]]
[[The Stomachs of the Ruminant - Anatomy & Physiology - Flashcards#The Rumen|The Rumen Flashcards]]
'''Video'''
[http://stream2.rvc.ac.uk/Anatomy/bovine/Pot0052.mp4 Pot 52 Lateral view of the Abdomen of a young Ruminant]
[http://stream2.rvc.ac.uk/Anatomy/bovine/pot0175.mp4 Pot 175 Sections of the Ruminant Stomach]
[http://stream2.rvc.ac.uk/Frean/sheep/LeftSideTopography.mp4 Left sided topography of the Ovine Abdomen and Thorax]
[http://stream2.rvc.ac.uk/Frean/sheep/RightSideTopography.mp4 Right sided topography of the Ovine Abdomen]
[http://stream2.rvc.ac.uk/Frean/sheep/RuminantStomachStructure.mp4 Structure of the ruminant forestomachs]
|backcolour =BCED91
|linkpage =Alimentary - Anatomy & Physiology
|linktext =Alimentary System
|maplink = Alimentary (Concept Map)- Anatomy & Physiology
|pagetype =Anatomy
|subtext1=STOMACH AND ABOMASUM
|sublik1=Stomach and Abomasum - Anatomy & Physiology
}}
<br>
[[Image:Rumen Topography Sheep.jpg|thumb|right|150px|Rumen Topography (Sheep) - Copyright RVC 2008]]
==Introduction==
The rumen is the first chamber of the ruminant stomach. It is the largest chamber and has regular contractions to move food around for digestion, eliminate gases through [[Eructation - Anatomy & Physiology|eructation]] and send food particles back to the mouth for [[Mastication|remastication]].
The rumen breaks down food particles through mechanical digestion and fermentation with the help of symbiotic microbes. [[Volatile Fatty Acids - Anatomy & Physioogy|Volatile fatty acids]] are the main product of ruminant digestion.
==Structure==
[[Image:Rumen Anatomy Sheep.jpg|thumb|right|150px|Rumen Anatomy (Sheep) - Copyright RVC 2008]]
*Grooves correspond with thickened smooth muscle pillars on the inside of the rumen
**Ruminal pillars divide the dorsal and ventral ruminal sacs
**Coronary pillars divide the caudal blind sacs
**Cranial pillar divides the dorsal and cranial sacs
*Covered by greater omentum
*38-40°C
*Anaerobic
*pH 6.7
*Buffered
*Large holding capacity
*Water intake lowers the ruminal temperature so bacteria are tolerant to temperature changes towards the lower end of the scale
*Objects are often lodged in the rumino-reticular fold. When the rumen contracts, the object can be pushed through the [[The Reticulum|reticulum]] wall into the [[Structure of the Heart - Anatomy & Physiology#Pericardium|pericardium]] and [[Heart - Anatomy & Physiology|heart]].
*Laterally compressed
*Extends from the cardia at the level of the 8th rib to the pelvic inlet
*Serosa covers the entire rumen except dorsally where the rumen attaches to the abdominal roof allowing more freedom for ruminal movement and expansion
*Ruminal contractions can be felt for in the left paralumbar fossa
*1-2 contractions should be felt per minute
*Opening at the cardia into both the rumen and [[The Reticulum|reticulum]] is called the reticuluar groove (see [[Oesophageal groove|oesophageal groove]])
==Function==
*Waste removal
*Simpler products of digestion are assilimated directly, others continue down the digestive tract for further digestion
*Mixes food
*Moves food forwards through the stomach chambers
*Sensors in the rumen can determine the courseness of the food. Course, tough feed needs stronger and more frequent ruminal contractions.
*Vagus nerve ([[Nervous System - CNS - Anatomy & Physiology#Innervation - Cranial Nerves|CN X]]) is needed for control of stomach movements
*Reflex control through sensory receptors in the medulla
*See [[Rumination - Anatomy & Physiology|rumination]]
*See [[Eructation - Anatomy & Physiology|eructation]]
==Ruminoreticular contraction==
[[Image:Contractions of the ruminoreticulum diagram.jpg|thumb|right|150px|Diagram of the contractions of the ruminoreticulum - Copyright RVC 2008]]
*Primary mixes food
**Mixing cycle of ruminoreticulum
**2 contractions of the [[The Reticulum|reticulum]] (2nd most powerful) which continues over the rumen
**Ingesta flows from the [[The Reticulum|reticulum]] to cranial ruminal sac to [[The Reticulum|reticulum]] (or ventral sac)
**Every 60 seconds
*Secondary lets gas out
**See [[Eructation - Anatomy & Physiology|eructation]]
**Ingesta flows from ventral blind sac to dorsal blind sac to dorsal sac ([[Eructation - Anatomy & Physiology|eructation]]) to ventral sac
==Vasculature==
*Cranial mesenteric artery
*Celiac artery
*Right and left ruminal arteries
==Innervation==
*Dorsal vagus ([[Nervous System - CNS - Anatomy & Physiology#Innervation - Cranial Nerves|CN X]]) (most important)
*Ventral vagus ([[Nervous System - CNS - Anatomy & Physiology#Innervation - Cranial Nerves|CN X]])
==Lymphatics==
*Caudal mediastinal lymph node enlargement put pressure on the dorsal vagus effecting ruminal contractions
*Numerous small lymph nodes are scattered in the ruminal grooves
*The lymph drains to larger atrial nodes between the cardia and [[The Omasum|omasum]], then to the cistera chyli
==Histology==
[[Image:Rumen Histology Sheep.jpg|thumb|right|150px|Rumen Histology (Sheep) - Copyright RVC 2008]]
*Keratinised stratified squamous epithelium
*Non-glandular
*No lamina muscularis
*2 thick layers of tunica muscularis- inner circular and outer longitudinal
*Interior surface of the rumen forms numerous papillae
**Papillae can be long and foliate
**Papillae can be short and pointed
**Up to 6mm in length
**Animals fed on rough grass or in the dry season have longer papillae
**Animals fed on digestible feed or in the wet season have shorter papillae (1-2mm in length)
**Fewer dorsally
**Increase surface area for [[Volatile Fatty Acids - Anatomy & Physioogy|volatile fatty acid]] absorption
*The upper keratinised layer of papillae protects against abrasion
*The deeper layers of papillae metabolise the [[Volatile Fatty Acids - Anatomy & Physioogy|volatile fatty acids]]
==Rumen Microbes==
*Have a variety of microbes that can utilise many substrates
*Dominance of different bacterial species depends on pH. Ergo, microbial populations are not constant
*Microbes digest cellulose and hemi-cellulose
*Microbes provide a source of all amino acids
*Microbes synthesise vitamins (especially the B vitamins)
'''Rumen Microbial Population'''
*Bacteria
**Over 2000 species
**99.5% obligate anaerobes
*Protozoa
**Large
**Unicellular organisms
**Prey on bacteria
**Numbers affected by diet
*Fungi
**Digest fibre
**Numbers present usually low
'''Common Rumen Microbes'''
{| style="width:75%; height:200px" border="1"
!'''Species'''
!'''Type'''
!'''pH'''
|-
| '''Ruminococcus flavefauens'''
| Fibre
| 6.15
|-
| '''Fibrobacter succinogens'''
| Fibre
| 6
|-
| '''Megashpaera eisdeni'''
| Lactate user
| 4.9
|-
| '''Streptococcus bovis'''
| Lactate producer
| 4.55
|}
==Species Differences==
===Small Ruminats===
*Sheep and goats have a larger ventral ruminal sac than dorsal ruminal sac
*Cranial mesenteric artery and celiac artery come off the same root
===Bovine===
*Cranial mesenteric artery and celiac artery are close in the cow
*Dairy cows have a rumen pH of 5.5 due to more digestible feed
==Links==
[[The Reticulum|The Reticulum - Anatomy & Physiology]]
[[The Omasum|The Omasum - Anatomy & Physiology]]
[[The Abomasum|The Abomasum- Anatomy & Physiology]]
[[The Stomachs of the Ruminant - Anatomy & Physiology - Flashcards#The Rumen|The Rumen Flashcards]]
'''Video'''
[http://stream2.rvc.ac.uk/Anatomy/bovine/Pot0052.mp4 Pot 52 Lateral view of the Abdomen of a young Ruminant]
[http://stream2.rvc.ac.uk/Anatomy/bovine/pot0175.mp4 Pot 175 Sections of the Ruminant Stomach]
[http://stream2.rvc.ac.uk/Frean/sheep/LeftSideTopography.mp4 Left sided topography of the Ovine Abdomen and Thorax]
[http://stream2.rvc.ac.uk/Frean/sheep/RightSideTopography.mp4 Right sided topography of the Ovine Abdomen]
[http://stream2.rvc.ac.uk/Frean/sheep/RuminantStomachStructure.mp4 Structure of the ruminant forestomachs]