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Abomasum - Anatomy & Physiology (view source)
Revision as of 15:56, 9 September 2010
, 15:56, 9 September 2010no edit summary
==Introduction==
==Overview==
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.
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.
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.
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.
[[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.
==Structure==
==Structure==
[[Image:Abomasum Anatomy Sheep.jpg|thumb|right|150px|Abomasum Anatomy (Sheep) - Copyright RVC 2008]]
[[Image:Abomasum Anatomy Sheep.jpg|thumb|right|250px|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). There is some control at the '''pyloric sphincter'''. The abomasum is large in newborn animals. The proximal ends of the abomasal folds forms a plug preventing reflux into the '''[[Omasum - Anatomy & Physiology|omasum]]'''. It has thin walls and a serousa covering.
==Function==
==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==
==Vasculature==
The vasculature of the abomasum includes the '''cranial mesenteric artery''', the '''celiac artery''' and the '''left gastric''' and '''left gasrtoepiploic''' arteries.
==Innervation==
==Innervation==
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).
==Lymphatics==
==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 - Anatomy & Physiology|omasum]]''', then to the hepatic lymph nodes.
==Species Differences==
==Species Differences==
===Small Ruminants===
===Small Ruminants===
The abomasum can contact the [[Liver - Anatomy & Physiology|liver]]. The abomasum is proportionately larger than in cattle.
==Links==
==Test yourself with the stomach of ruminants flashcards==
[[The Stomachs of the Ruminant - Anatomy & Physiology - Flashcards#The Abomasum|The Abomasum Flashcards]]
'''Test yourself with [[The Stomachs of the Ruminant - Anatomy & Physiology - Flashcards#The Abomasum|the Abomasum Flashcards]]'''
[[Rumen - Anatomy & Physiology|The Rumen - Anatomy & Physiology]]
'''Click here for [[Abomasum - Histology|Abomasum Histology]]'''
[[Reticulum - Anatomy & Physiology|The Reticulum - Anatomy & Physiology]]
'''Click here for [[Rumen - Anatomy & Physiology|Rumen - Anatomy & Physiology]]'''
[[Omasum - Anatomy & Physiology|The Omasum - Anatomy & Physiology]]
'''Click here for [[Reticulum - Anatomy & Physiology|Reticulum - Anatomy & Physiology]]'''
'''Video'''
'''Click here for [[Omasum - Anatomy & Physiology|Omasum - Anatomy & Physiology]]'''
'''Video links:'''
[http://stream2.rvc.ac.uk/Anatomy/bovine/pot0175.mp4 Pot 175 Sections of the Ruminant Stomach]
1.[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/ovine/Pot0047.mp4 Pot 47 Ovine Omasum and Abomasum]
2.[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]
3.[http://stream2.rvc.ac.uk/Anatomy/ovine/Pot0047.mp4 Pot 47 Ovine Omasum and Abomasum]
[http://stream2.rvc.ac.uk/Frean/sheep/RightSideTopography.mp4 Right sided topography of the Ovine Abdomen]
4.[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/RuminantStomachStructure.mp4 Structure of the ruminant forestomachs]
5.[http://stream2.rvc.ac.uk/Frean/sheep/RightSideTopography.mp4 Right sided topography of the Ovine Abdomen]
6.[http://stream2.rvc.ac.uk/Frean/sheep/RuminantStomachStructure.mp4 Structure of the ruminant forestomachs]
[[Category:Stomach - Anatomy & Physiology]]
[[Category:Stomach - Anatomy & Physiology]]
[[Category:To Do - A&P]]
[[Category:To Do - AimeeHicks]]