Difference between revisions of "Abomasum - Anatomy & Physiology"

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==Overview==
|linkpage =Alimentary - Anatomy & Physiology
 
|linktext =Alimentary System
 
|maplink =
 
|subtext1=STOMACH AND ABOMASUM
 
|sublik1=Stomach and Abomasum - Anatomy & Physiology
 
}}
 
<br>
 
==Introduction==
 
  
The abomasum is the fourth chamber in the ruminant. It functions similarily to the [[Monogastric Stomach - Anatomy & Physiology|carnivore stomach]] as it is glandular and functions to digest food chemically, rather than mechanically or by fermentation like the other 3 chambers of the ruminant stomach.
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The '''abomasum''' is the fourth chamber in the ruminant. It functions similarly to the [[Monogastric Stomach - Anatomy & Physiology|carnivore stomach]] as it is glandular and digests food chemically, rather than mechanically or by fermentation like the other 3 chambers of the ruminant stomach.
  
The abomasum differs in its position within the abdomen, depending on fullness of the other chambers of the stomach, intrinsic abomasonal activity, contractions of the [[The Rumen - Anatomy & Physiology|rumen]] and [[The Reticulum - Anatomy & Physiology|reticulum]] (to which it is attached) and by age and pregnancy.
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The '''abomasum''' differs in its position within the abdomen, depending on fullness of the other chambers of the stomach, intrinsic abomasonal activity, contractions of the '''[[Rumen - Anatomy & Physiology|rumen]]''' and '''[[Reticulum - Anatomy & Physiology|reticulum]]''' (to which it is attached) and by age and pregnancy status.
  
 
[[Displaced Abomasum|Displacement of the abomasum]] to the left or to the right is a common disorder affecting dairy cows due to high concentrate feed.
 
[[Displaced Abomasum|Displacement of the abomasum]] to the left or to the right is a common disorder affecting dairy cows due to high concentrate feed.
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==Structure==
 
==Structure==
  
[[Image:Abomasum Anatomy Sheep.jpg|thumb|right|150px|Abomasum Anatomy (Sheep) - Copyright RVC 2008]]
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[[Image:Abomasum Anatomy Sheep.jpg|thumb|right|250px|Abomasum Anatomy (Sheep) - Copyright RVC 2008]]
*Lies upon the abdominal floor
 
 
 
*Cranial part split into pylorus and body
 
 
 
*Caudal part
 
 
 
*Covered by lesser omentum
 
 
 
*15-20 folds inside
 
 
 
*Torus at pyloric exit
 
 
 
*Outflow fairly constant
 
 
 
*Motility at pylorus (peristalsis)
 
 
 
*Some control at pyloric sphincter
 
 
 
*Large in newborn
 
 
 
*Proximal ends of the abomasal folds forms a plug preventing reflux into the [[The Omasum - Anatomy & Physiology|omasum]]
 
 
 
*Thin walls
 
 
 
*Serousa covering
 
  
 +
The '''abomasum''' lies upon the abdominal floor. The cranial part is split into the '''pylorus''' and '''body'''. There is also a caudal part. It is covered by the '''lesser omentum'''. It has 15-20 folds inside. The '''torus''' is at the pyloric exit. The outflow is fairly constant. There is motility at the '''pylorus''' (peristalsis) and some control at the '''pyloric sphincter'''. The abomasum is large in newborn animals. The proximal ends of the abomasal folds form a plug preventing reflux into the '''[[Omasum - Anatomy & Physiology|omasum]]'''. It has thin walls and a serosa covering.
  
 
==Function==
 
==Function==
  
*Chemical breakdown of food
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The function of the abomasum is the chemical breakdown of food. It secretes '''hydrochloric acid''' and '''pepsinogen'''. It has some intrinsic motility. Impaired motility can cause distension. The movements are slow, contractions occur first in the proximal part and are more forceful at the pyloric part.
 
 
*Secretes hydrochloric acid and pepsinogen
 
 
 
*Some intrinsic motility
 
 
 
*Impaired motility can cause distension
 
 
 
*Movements are slow
 
**Contraction first of proximal part
 
**More forceful contraction at pyloric part
 
 
 
  
 
==Vasculature==
 
==Vasculature==
  
*Cranial mesenteric artery
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The vasculature of the abomasum includes the '''cranial mesenteric artery''', the '''celiac artery''' and the '''left gastric''' and '''left gastroepiploic''' arteries.
 
 
*Celiac artery
 
 
 
*Left gastric and left gasrtoepiploic arteries
 
 
 
  
 
==Innervation==
 
==Innervation==
  
*Dorsal vagus nerve ([[Cranial Nerves - Anatomy & Physiology|CN X]])  
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The innervation of the abomasum includes the '''dorsal vagus nerve''' ([[Cranial Nerves - Anatomy & Physiology|CN X]]) and the '''ventral vagus nerve''' ([[Cranial Nerves - Anatomy & Physiology|CN X]]) (most important).
 
 
*Ventral vagus nerve ([[Cranial Nerves - Anatomy & Physiology|CN X]]) (most important)
 
  
 
==Lymphatics==
 
==Lymphatics==
  
*Single lymph nodules are present at the junction between epithelium and lamina propria
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Single lymph nodules are present at the junction between the epithelium and the lamina propria. Numerous small lymph nodes are scattered in the abomasal curvatures. The lymph drains to larger atrial nodes between the '''cardia''' and '''[[Omasum - Anatomy & Physiology|omasum]]''', then to the hepatic lymph nodes.
 
 
*Numerous small lymph nodes are scattered in the abomasal curvatures
 
 
 
*The lymph drains to larger atrial nodes between the cardia and [[The Omasum - Anatomy & Physiology|omasum]], then to the hepatic lymph nodes
 
 
 
  
 
==Histology==
 
==Histology==
  
 
[[Image:Abomasum Histology Sheep.jpg|thumb|right|150px|Abomasum Histology (Sheep) - Copyright RVC 2008]]
 
[[Image:Abomasum Histology Sheep.jpg|thumb|right|150px|Abomasum Histology (Sheep) - Copyright RVC 2008]]
*Simple columnar epithelium
+
The abomasum has a simple columnar epithelium. There are 3 layers of '''''tunica muscularis''''' - inner oblique, middle circular and outer longitudinal. The '''''lamina muscularis''''' is thicker and has 3 separate layers.
 
 
*3 layers of tunica muscularis- inner oblique, middle circular and outer longitudinal
 
 
 
*Lamina muscularis thicker (3 separate layers)
 
 
 
*Gastric glands in lamina propria of mucosal layer in pyloric region (lighter part)
 
 
 
*Heavily coated by mucous for protection
 
 
 
*Submucosa contains loose connective tissue, many blood vessels and unilocular adipocytes
 
 
 
*Deep gastric pits
 
 
 
*Coiled glands in lamina propria opening into gastric pits
 
 
 
*Pink inner mucosa
 
 
 
*Rugae are present in the pyloric region
 
 
 
*Torus (large swelling) is present at the pyloric passage to narrow the lumen
 
 
 
*Dark mucosa of fundus and body contain peptic glands
 
  
 +
Gastric glands are present in the '''''lamina propria''''' of the mucosal layer in the pyloric region (lighter part). The abomasum is heavily coated by mucous for protection. The submucosa contains loose connective tissue, many blood vessels and unilocular adipocytes. The coiled glands in the ''lamina propria'' open into deep gastric pits. The inner mucosa is pink. '''Rugae''' are present in the pyloric region and a '''torus''' (large swelling) is present at the pyloric passage to narrow the lumen. The dark mucosa of the fundus and body contains peptic glands.
  
 
==Species Differences==
 
==Species Differences==
  
 
===Small Ruminants===
 
===Small Ruminants===
*Abomasum can contact [[Liver - Anatomy & Physiology|liver]]
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The abomasum can contact the [[Liver - Anatomy & Physiology|liver]]. The abomasum is proportionately larger than in cattle.
 
 
*Abomasum is proportionately larger than in cattle
 
 
 
==Test yourself with the stomach of ruminants flashcards==
 
 
 
[[The Stomachs of the Ruminant - Anatomy & Physiology - Flashcards#The Abomasum|The Abomasum Flashcards]]
 
  
 
==Links==
 
==Links==
  
[[The Rumen - Anatomy & Physiology|The Rumen - Anatomy & Physiology]]
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'''Click here for [[Rumen - Anatomy & Physiology|Rumen - Anatomy & Physiology]]'''
 
 
[[The Reticulum - Anatomy & Physiology|The Reticulum - Anatomy & Physiology]]
 
 
 
[[The Omasum - Anatomy & Physiology|The Omasum - 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/Anatomy/ovine/Pot0047.mp4 Pot 47 Ovine Omasum and Abomasum]
 
 
 
[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]
 
  
 +
'''Click here for [[Reticulum - Anatomy & Physiology|Reticulum - Anatomy & Physiology]]'''
  
 +
'''Click here for [[Omasum - Anatomy & Physiology|Omasum - Anatomy & Physiology]]'''
 +
<br><br>
 +
{{Learning
 +
|flashcards = [[Abomasum Flashcards]]
 +
<!-----|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/Anatomy/ovine/Pot0047.mp4 Ovine Omasum and Abomasum]<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]---->
 +
|powerpoints = [[Ruminant Gastrointestinal Tract Histology resource|Histology of the ruminant gastrointestinal tract]]
 +
}}
  
[[Category:Alimentary System - Anatomy & Physiology]]
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==Webinars==
 +
<rss max="10" highlight="none">https://www.thewebinarvet.com/gastroenterology-and-nutrition/webinars/feed</rss>
 +
[[Category:Stomach - Anatomy & Physiology]]
 +
[[Category:A&P Done]]
 +
[[Category:Alimentary Anatomy - Cattle]]

Latest revision as of 18:04, 2 November 2022


Overview

The abomasum is the fourth chamber in the ruminant. It functions similarly to the carnivore stomach as it is glandular and digests food chemically, rather than mechanically or by fermentation like the other 3 chambers of the ruminant stomach.

The abomasum differs in its position within the abdomen, depending on fullness of the other chambers of the stomach, intrinsic abomasonal activity, contractions of the rumen and reticulum (to which it is attached) and by age and pregnancy status.

Displacement of the abomasum to the left or to the right is a common disorder affecting dairy cows due to high concentrate feed.


Structure

Abomasum Anatomy (Sheep) - Copyright RVC 2008

The abomasum lies upon the abdominal floor. The cranial part is split into the pylorus and body. There is also a caudal part. It is covered by the lesser omentum. It has 15-20 folds inside. The torus is at the pyloric exit. The outflow is fairly constant. There is motility at the pylorus (peristalsis) and some control at the pyloric sphincter. The abomasum is large in newborn animals. The proximal ends of the abomasal folds form a plug preventing reflux into the omasum. It has thin walls and a serosa covering.

Function

The function of the abomasum is the chemical breakdown of food. It secretes hydrochloric acid and pepsinogen. It has some intrinsic motility. Impaired motility can cause distension. The movements are slow, contractions occur first in the proximal part and are more forceful at the pyloric part.

Vasculature

The vasculature of the abomasum includes the cranial mesenteric artery, the celiac artery and the left gastric and left gastroepiploic arteries.

Innervation

The innervation of the abomasum includes the dorsal vagus nerve (CN X) and the ventral vagus nerve (CN X) (most important).

Lymphatics

Single lymph nodules are present at the junction between the epithelium and the lamina propria. Numerous small lymph nodes are scattered in the abomasal curvatures. The lymph drains to larger atrial nodes between the cardia and omasum, then to the hepatic lymph nodes.

Histology

Abomasum Histology (Sheep) - Copyright RVC 2008

The abomasum has a simple columnar epithelium. There are 3 layers of tunica muscularis - inner oblique, middle circular and outer longitudinal. The lamina muscularis is thicker and has 3 separate layers.

Gastric glands are present in the lamina propria of the mucosal layer in the pyloric region (lighter part). The abomasum is heavily coated by mucous for protection. The submucosa contains loose connective tissue, many blood vessels and unilocular adipocytes. The coiled glands in the lamina propria open into deep gastric pits. The inner mucosa is pink. Rugae are present in the pyloric region and a torus (large swelling) is present at the pyloric passage to narrow the lumen. The dark mucosa of the fundus and body contains peptic glands.

Species Differences

Small Ruminants

The abomasum can contact the liver. The abomasum is proportionately larger than in cattle.

Links

Click here for Rumen - Anatomy & Physiology

Click here for Reticulum - Anatomy & Physiology

Click here for Omasum - Anatomy & Physiology


Abomasum - Anatomy & Physiology Learning Resources
FlashcardsFlashcards logo.png
Flashcards
Test your knowledge using flashcard type questions
Abomasum Flashcards
Category:Histology PowerPointsPowerPoint.png
PowerPoint
Selection of relevant PowerPoint tutorials
Histology of the ruminant gastrointestinal tract


Webinars

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