Difference between revisions of "Abomasum - Anatomy & Physiology"

Revision as of 15:56, 14 August 2009

Introduction

The abomasum is the fourth chamber in the ruminant. It functions similarily to the 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 and reticulum (to which it is attached) and by age and pregnancy.

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

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 omasum

Thin walls

Serousa covering

Function

Chemical breakdown of food

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

Cranial mesenteric artery

Celiac artery

Left gastric and left gasrtoepiploic arteries

Innervation

Dorsal vagus nerve (CN X)

Ventral vagus nerve (CN X) (most important)

Lymphatics

Single lymph nodules are present at the junction between epithelium and 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

Simple columnar epithelium

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

Species Differences

Small Ruminants

Abomasum can contact liver

Abomasum is proportionately larger than in cattle

Links

The Rumen - Anatomy & Physiology

The Reticulum - Anatomy & Physiology

The Omasum - Anatomy & Physiology

The Abomasum Flashcards

Video

Pot 52 Lateral view of the Abdomen of a young Ruminant

Pot 175 Sections of the Ruminant Stomach

Pot 47 Ovine Omasum and Abomasum

Left sided topography of the Ovine Abdomen and Thorax

Right sided topography of the Ovine Abdomen

Structure of the ruminant forestomachs

@@ Line 1: / Line 1: @@
-{{OpenPagesTop}}
+{{toplink
-==Overview==
+|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>
+==Introduction==
-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 is the fourth chamber in the ruminant. It functions similarily to the [[Forestomach - 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 status.
+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.
-[[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.
+[[Stomach and Abomasum Physical Disruptions - Pathology#Displaced Abomasum in the Cow|Displacement of the abomasum]] to the left or to the right is a common disorder affecting dairy cows due to high concentrate feed.
 ==Structure==
-[[Image:Abomasum Anatomy Sheep.jpg|thumb|right|250px|Abomasum Anatomy (Sheep) - Copyright RVC 2008]]
+[[Image:Abomasum Anatomy Sheep.jpg|thumb|right|150px|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==
-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.
+*Chemical breakdown of food
+*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==
-The vasculature of the abomasum includes the '''cranial mesenteric artery''', the '''celiac artery''' and the '''left gastric''' and '''left gastroepiploic''' arteries.
+*Cranial mesenteric artery
+*Celiac artery
+*Left gastric and left gasrtoepiploic arteries
 ==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).
+*Dorsal vagus nerve ([[Cranial Nerves - Anatomy & Physiology|CN X]])
+*Ventral vagus nerve ([[Cranial Nerves - Anatomy & Physiology|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 - Anatomy & Physiology|omasum]]''', then to the hepatic lymph nodes.
+*Single lymph nodules are present at the junction between epithelium and lamina propria
+*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==
 [[Image:Abomasum Histology Sheep.jpg|thumb|right|150px|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.
+*Simple columnar epithelium
+*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==
 ===Small Ruminants===
-The abomasum can contact the [[Liver - Anatomy & Physiology|liver]]. The abomasum is proportionately larger than in cattle.
+*Abomasum can contact [[Liver - Anatomy & Physiology|liver]]
+*Abomasum is proportionately larger than in cattle
 ==Links==
-'''Click here for [[Rumen - Anatomy & Physiology|Rumen - Anatomy & Physiology]]'''
+[[The Rumen - Anatomy & Physiology|The Rumen - Anatomy & Physiology]]
+[[The Reticulum - Anatomy & Physiology|The Reticulum - Anatomy & Physiology]]
-'''Click here for [[Reticulum - Anatomy & Physiology|Reticulum - Anatomy & Physiology]]'''
+[[The Omasum - Anatomy & Physiology|The Omasum - Anatomy & Physiology]]
-'''Click here for [[Omasum - Anatomy & Physiology|Omasum - Anatomy & Physiology]]'''
+[[The Stomachs of the Ruminant - Anatomy & Physiology - Flashcards#The Abomasum|The Abomasum Flashcards]]
-<br><br>
-{{Learning
+'''Video'''
-|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]---->
+[http://stream2.rvc.ac.uk/Anatomy/bovine/Pot0052.mp4 Pot 52 Lateral view of the Abdomen of a young Ruminant]
-|powerpoints = [[Ruminant Gastrointestinal Tract Histology resource|Histology of the ruminant gastrointestinal tract]]
-}}
+[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]
-==Webinars==
+[http://stream2.rvc.ac.uk/Frean/sheep/RuminantStomachStructure.mp4 Structure of the ruminant forestomachs]
-<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]]