Difference between revisions of "Rumen - Anatomy & Physiology"

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[[Image:Rumen Topography Sheep.jpg|thumb|right|150px|Rumen Topography (Sheep) - Copyright RVC 2008]]
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[[Image:Rumen Topography Sheep.jpg|thumb|right|250px|Rumen Topography (Sheep) - Copyright RVC 2008]]
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==Introduction==
  
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==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]].
  
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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|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|Volatile fatty acids]] are the main product of ruminant digestion.
+
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==
 
==Structure==
  
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[[Image:Rumen Anatomy Sheep.jpg|thumb|right|250px|Rumen Anatomy (Sheep) - Copyright RVC 2008]]
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[[Image:Rumen Anatomy Sheep.jpg|thumb|right|150px|Rumen Anatomy (Sheep) - Copyright RVC 2008]]
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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. The '''cranial pillar''' divides the dorsal and cranial sacs. It is covered by the greater omentum. The rumen is 38-40°C, anaerobic and has a pH of 6.7. It is buffered and has a 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 [[Reticulum - Anatomy & Physiology|reticulum]] wall into the [[Heart Structure - Anatomy & Physiology#Pericardium|pericardium]] and [[Heart - Anatomy & Physiology|heart]].
+
*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 [[Reticulum - Anatomy & Physiology|reticulum]] wall into the [[Structure of the Heart - Anatomy & Physiology#Pericardium|pericardium]] and [[Heart - Anatomy & Physiology|heart]].
  
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The rumen is laterally compressed and extends from the cardia at the level of the 8th rib to the pelvic inlet. The 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. The opening at the cardia into both the rumen and [[Reticulum - Anatomy & Physiology|reticulum]] is called the reticular groove (see [[Oesophageal Groove|oesophageal groove]]).
+
*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 [[Reticulum - Anatomy & Physiology|reticulum]] is called the reticuluar groove (see [[Oesophageal Groove|oesophageal groove]])
  
 
==Function==
 
==Function==
  
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The rumen is involved in waste removal. Simpler products of digestion are assimilated directly, others continue down the digestive tract for further digestion. It mixes food and moves it forwards through the stomach chambers. Sensors in the rumen can determine the coarseness of the food. Coarse, tough feed needs stronger and more frequent ruminal contractions. The '''vagus nerve''' ([[Cranial Nerves - Anatomy & Physiology|CN X]]) is needed for control of stomach movements. The reflex control is through sensory receptors in the medulla.
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*Waste removal
 +
 
 +
*Simpler products of digestion are assilimated directly, others continue down the digestive tract for further digestion
  
−
See [[Rumination|rumination]] and [[Eructation|eructation]].
+
*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 ([[Cranial Nerves - Anatomy & Physiology|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==
 
==Ruminoreticular contraction==
  
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[[Image:Contractions of the ruminoreticulum diagram.jpg|thumb|right|250px|Diagram of the contractions of the ruminoreticulum - Copyright RVC 2008]]
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[[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 [[Reticulum - Anatomy & Physiology|reticulum]] (2nd most powerful) which continues over the rumen
 +
**Ingesta flows from the [[Reticulum - Anatomy & Physiology|reticulum]] to cranial ruminal sac to [[Reticulum - Anatomy & Physiology|reticulum]] (or ventral sac)
 +
**Every 60 seconds
  
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The contractions have two main functions:
+
*Secondary lets gas out
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:Primary contraction mixes food by a ruminoreticuluar mixing cycle. There are 2 contractions of the reticulum (2nd most powerful) which continue over the [[Rumen - Anatomy & Physiology|rumen]]. Ingesta flows from the reticulum to cranial rumenal sac and then to reticulum (or ventral sac). It occurs every 60 seconds.
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**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
  
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:The secondary contraction lets gas out (see [[Eructation|eructation]]). Ingesta flows from the ventral blind sac to the dorsal blind sac then to dorsal sac (eructation) and to the ventral sac.
+
==Vasculature==
  
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==Vasculature==
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*Cranial mesenteric artery
 +
 
 +
*Celiac artery
 +
 
 +
*Right and left ruminal arteries
  
−
The rumen receives blood from the '''celiac artery''' which branches into the '''right''' and '''left ruminal arteries'''.
 
  
 
==Innervation==
 
==Innervation==
  
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The rumen is innervated by the '''dorsal vagus''' nerve ([[Cranial Nerves - Anatomy & Physiology|CN X]]) (most important) and '''ventral vagus''' ([[Cranial Nerves - Anatomy & Physiology|CN X]]) nerve.
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*Dorsal vagus ([[Cranial Nerves - Anatomy & Physiology|CN X]]) (most important)
 +
 
 +
*Ventral vagus ([[Cranial Nerves - Anatomy & Physiology|CN X]])
  
 
==Lymphatics==
 
==Lymphatics==
  
−
The caudal '''mediastinal lymph node''' enlargement puts pressure on the dorsal vagus effecting ruminal contractions. There are numerous small lymph nodes scattered in the ruminal grooves. The lymph drains to larger atrial nodes between the cardia and the [[Omasum - Anatomy & Physiology|omasum]], then to the cistera chyli.
+
*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 [[Omasum - Anatomy & Physiology|omasum]], then to the cistera chyli
 +
 
 +
==[[Rumen - Histology|Histology]]==
  
 
==Rumen Microbes==
 
==Rumen Microbes==
  
−
The rumen has a variety of microbes that can utilise many substrates. The dominance of different bacterial species depends on pH. Ergo, microbial populations are not constant. Microbes digest cellulose and hemi-cellulose and provide a source of all amino acids. Microbes also synthesise vitamins (especially the B vitamins).
+
*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==
+
'''Rumen Microbial Population'''
  
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'''Bacteria'''
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*Bacteria
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There are over 2000 species, 99.5% are obligate anaerobes.
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**Over 2000 species
 +
**99.5% obligate anaerobes
  
−
'''Protozoa'''
+
*Protozoa
−
Large, unicellular organisms that prey on bacteria. Numbers are affected by diet.
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**Large
 +
**Unicellular organisms
 +
**Prey on bacteria
 +
**Numbers affected by diet
  
−
'''Fungi'''
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*Fungi
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Digest fibre. Numbers present are usually low.
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**Digest fibre
 +
**Numbers present usually low
  
 
'''Common Rumen Microbes'''
 
'''Common Rumen Microbes'''
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| 4.55
 
| 4.55
 
|}
 
|}
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==Histology==
 
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[[Image:Rumen Histology Sheep.jpg|thumb|right|250px|Rumen Histology (Sheep) - Copyright RVC 2008]]
 
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The rumen has a '''keratinised stratified squamous epithelium'''. It is non-glandular and has no '''lamina muscularis'''.
 
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There are two thick layers of '''tunica muscularis''', the inner circular and the outer longitudinal. The interior surface of the rumen forms numerous papillae. The papillae can be long and foliated or short and pointed. They are up to 6mm in length. Animals fed on rough grass or in the dry season have longer papillae, whereas animals fed on digestible feed or in the wet season have shorter papillae (1-2mm in length). There are fewer papillae present dorsally. They increase the surface area for [[Volatile Fatty Acids|volatile fatty acid]] absorption. The upper keratinised layer of papillae also protects the rumen against abrasion. The deeper layers of papillae metabolise the [[Volatile Fatty Acids|volatile fatty acids]].
 
  
 
==Species Differences==
 
==Species Differences==
  
−
===Small Ruminants===
+
===Small Ruminats===
 +
*Sheep and goats have a larger ventral ruminal sac than dorsal ruminal sac
  
−
Sheep and goats have a larger ventral ruminal sac than dorsal ruminal sac. The cranial mesenteric artery and celiac artery come off the same root.
+
*Cranial mesenteric artery and celiac artery come off the same root
  
 
===Bovine===
 
===Bovine===
 +
*Cranial mesenteric artery and celiac artery are close in the cow
  
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The 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.
+
*Dairy cows have a rumen pH of 5.5 due to more digestible feed
 
<br />
 
<br />
 
<br />
 
<br />
 +
==Test yourself with the Stomachs of the Ruminant Flashcards==
 +
 +
[[The_Stomachs_of_the_Ruminant_-_Anatomy_%26_Physiology_-_Flashcards|Ruminant Stomach Flashcards]]
  
 
==Links==
 
==Links==
  
−
'''Click here for information on [[Reticulum - Anatomy & Physiology|the Reticulum - Anatomy & Physiology]]'''
+
[[Reticulum - Anatomy & Physiology|The Reticulum - Anatomy & Physiology]]
 +
 
 +
[[Omasum - Anatomy & Physiology|The Omasum - Anatomy & Physiology]]
 +
 
 +
[[The Abomasum - Anatomy & Physiology|The Abomasum- Anatomy & Physiology]]
 +
 
 +
'''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]
  
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'''Click here for information on [[Omasum - Anatomy & Physiology|the Omasum - Anatomy & Physiology]]'''
+
[http://stream2.rvc.ac.uk/Frean/sheep/RuminantStomachStructure.mp4 Structure of the ruminant forestomachs]
  
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'''Click here for information on [[Abomasum - Anatomy & Physiology|the Abomasum- Anatomy & Physiology]]'''
 
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<br><br>
 
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{{Learning
 
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|flashcards = [[Rumen Flashcards]]
 
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|videos = [http://stream2.rvc.ac.uk/Anatomy/bovine/Pot0052.mp4 Lateral view of the Abdomen of a young Ruminant]<br>[http://stream2.rvc.ac.uk/Anatomy/bovine/pot0175.mp4 Sections of the Ruminant Stomach]<br>[http://stream2.rvc.ac.uk/Frean/sheep/LeftSideTopography.mp4 Left sided topography of the Ovine Abdomen and Thorax]<br>[http://stream2.rvc.ac.uk/Frean/sheep/RightSideTopography.mp4 Right sided topography of the Ovine Abdomen]<br>[http://stream2.rvc.ac.uk/Frean/sheep/RuminantStomachStructure.mp4 Structure of the ruminant forestomachs]
 
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|OVAM = [http://www.onlineveterinaryanatomy.net/content/sheep-rumen-external-aspect Sheep Rumen (external aspect)]
 
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}}
 
  
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==Webinars==
 
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<rss max="10" filterout="nutrition" highlight="cattle cow cows">https://www.thewebinarvet.com/gastroenterology-and-nutrition/webinars/feed</rss>
 
  
 
[[Category:Stomach - Anatomy & Physiology]]
 
[[Category:Stomach - Anatomy & Physiology]]
−
[[Category:A&P Done]]
 
−
[[Category:Alimentary Anatomy - Cattle]]
 

Revision as of 14:03, 6 September 2010

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 and send food particles back to the mouth for remastication.

The rumen breaks down food particles through mechanical digestion and fermentation with the help of symbiotic microbes. Volatile fatty acids are the main product of ruminant digestion.

Structure

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 reticulum wall into the pericardium and 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

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 (CN X) is needed for control of stomach movements
  • Reflex control through sensory receptors in the medulla

Ruminoreticular contraction

Diagram of the contractions of the ruminoreticulum - Copyright RVC 2008
  • Primary mixes food
    • Mixing cycle of ruminoreticulum
    • 2 contractions of the reticulum (2nd most powerful) which continues over the rumen
    • Ingesta flows from the reticulum to cranial ruminal sac to reticulum (or ventral sac)
    • Every 60 seconds
  • Secondary lets gas out
    • See eructation
    • Ingesta flows from ventral blind sac to dorsal blind sac to dorsal sac (eructation) to ventral sac

Vasculature

  • Cranial mesenteric artery
  • Celiac artery
  • Right and left ruminal arteries


Innervation

  • Dorsal vagus (CN X) (most important)
  • Ventral vagus (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 omasum, then to the cistera chyli

Histology

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

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



Test yourself with the Stomachs of the Ruminant Flashcards

Ruminant Stomach Flashcards

Links

The Reticulum - Anatomy & Physiology

The Omasum - Anatomy & Physiology

The Abomasum- Anatomy & Physiology

Video

Pot 52 Lateral view of the Abdomen of a young Ruminant

Pot 175 Sections of the Ruminant Stomach

Left sided topography of the Ovine Abdomen and Thorax

Right sided topography of the Ovine Abdomen

Structure of the ruminant forestomachs

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