Difference between revisions of "Duodenum - Anatomy & Physiology"

Latest revision as of 17:35, 7 December 2022

Introduction

Section of equine duodenum- © RVC 2008

The duodenum is the proximal part of the small intestine and extends from the pylorus of the stomach to the jejunum. It has descending and ascending portions and both portions have digestive and absorptive functions.

Structure

The descending duodenum passes out of the pylorus of the stomach (on the right side of the abdomen) and has a sigmoid flexure. It passes towards the right abdominal wall and rises dorsally. In its passage, it is related dorsally to the right lobe of the pancreas, ventrally to the jejunum and medially to the ascending colon and caecum. At a point between the right kidney and pelvic inlet, it turns medially and cranially around the root of the mesentery to become the ascending duodenum. The point of turn is called the caudal flexure of the duodenum. The ascending duodenum is shorter and bends ventrally to enter the mesentery and becomes the jejunum. The mesoduodenum attaches the duodenum to the dorsal abdominal wall. Within the mesoduodenum is the right lobe of the pancreas. The pancreatic and bile ducts open into the duodenum. The bile duct and one of the pancreatic ducts discharge into the proximal part of the duodenum by separate major duodenal papillae. The second pancreatic duct discharges a little more distally on a smaller papilla. The cranial part of the descending duodenum is attached to the liver by the hepatoduodenal ligament. This is a remnant of the ventral mesogastrium in the embryo. The bile duct runs within the hepatoduodenal ligament.

Vasculature

The duodenum receives blood from the coeliac artery and the cranial mesenteric artery. Both are branches of the aorta. The cranial mesenteric vein drains blood from the duodenum into the portal vein. This blood, carrying the products of digestion, enters the liver.

Species Differences

Canine

The duodenum is about 25cm long in canine species. The mesoduodenum is relatively long.

Equine

The mesoduodenum is relatively short, so the duodenum is closely tethered in a constant position. The descending duodenum is attached to the base of the caecum. The descending duodenum runs caudally beneath the liver to the caudal pole of the right kidney where it has it's caudal flexure to become the ascending duodenum.

Ruminant

The mesoduodenum is relatively short. The first part of the descending duodenum rises almost vertically within the ribcage, in close apposition to the liver. It turns level with the tuber coxae. The first part of the duodenum is attached to the liver by the lesser omentum. The descending duodenum also provides attachment for the superficial and deep sheets of the greater omentum.

Porcine

The small intestine is comparable to the dog. The mesoduodenum is relatively long.

Links

Click here for more information on the Pathology of the Small and Large Intestine

Duodenum - Anatomy & Physiology Learning Resources
Vetstream To reach the Vetstream content, please select	Canis, Felis, Lapis or Equis
Flashcards Test your knowledge using flashcard type questions	Duodenum anatomy
Videos Selection of relevant videos	Ruminant small and large intestine potcast Ruminant abdomen potcast Foal gastrointestinal tract potcast Lateral view of the feline thorax and abdomen potcast Female dog abdomen dissection Abdominal viscera of the horse dissection Equine left-sided abdominal and thoracic topography dissection Equine left-sided abdominal and thoracic topography dissection 2 Ovine large and small intestine dissection Porcine abdomen dissection

Webinars

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-<big><center>[[Alimentary - Anatomy & Physiology|'''BACK TO ALIMENTARY - ANATOMY & PHYSIOLOGY''']]</center></big>
+{{OpenPagesTop}}
-<big><center>[[Small Intestine - Anatomy & Physiology|'''BACK TO SMALL INTESTINE - ANATOMY AND PHYSIOLOGY]]</center></big>
 ==Introduction==
-The duodenum is the proximal part of the small intestine. It extends from the pylorus of the stomach to the jejunum. Both the pancreatic and bile ducts open into the duodenum.
+[[Image:Section of duodenum from horse.JPG|thumb|right|250px|Section of equine duodenum- © RVC 2008]]
+The duodenum is the proximal part of the small intestine and extends from the '''pylorus''' of the [[Monogastric Stomach - Anatomy & Physiology|stomach]] to the '''[[Jejunum - Anatomy & Physiology|jejunum]]'''. It has descending and ascending portions and both portions have digestive and absorptive functions.
 ==Structure==
+The descending duodenum passes out of the '''pylorus''' of the [[Monogastric Stomach - Anatomy & Physiology|stomach]] (on the right side of the abdomen) and has a sigmoid flexure. It passes towards the right abdominal wall and rises dorsally. In its passage, it is related dorsally to the right lobe of the [[Pancreas - Anatomy & Physiology|pancreas]], ventrally to the [[Jejunum - Anatomy & Physiology|jejunum]] and medially to the ascending [[Colon - Anatomy & Physiology|colon]] and [[Caecum - Anatomy & Physiology|caecum]].
-*It has descending and ascending portions.
+At a point between the right [[Renal Anatomy - Anatomy & Physiology#Common Anatomy|kidney]] and pelvic inlet, it turns medially and cranially around the root of the mesentery to become the ascending duodenum. The point of turn is called the ''caudal flexure'' of the duodenum.
-**The descending duodenum passes out of the pylorus of the stomach (on the right side of the abdomen) and has a sigmoid flexure. It passes towards the right abdominal wall and rises  dorsally. In its passage it is related dorsally to the right lobe of the pancreas, ventrally to the jejunum and medially to the ascending colon and caecum.
+The ascending duodenum is shorter and bends ventrally to enter the mesentery and becomes the [[Jejunum - Anatomy & Physiology|jejunum]]. The '''mesoduodenum''' attaches the duodenum to the dorsal abdominal wall. Within the mesoduodenum is the right lobe of the [[Pancreas - Anatomy & Physiology|pancreas]]. The pancreatic and bile ducts open into the duodenum. The bile duct and one of the pancreatic ducts discharge into the proximal part of the duodenum by separate ''major duodenal papillae''. The second pancreatic duct discharges a little more distally on a smaller papilla. The cranial part of the descending duodenum is attached to the [[Liver - Anatomy & Physiology|liver]] by the '''hepatoduodenal ligament'''. This is a remnant of the [[Monogastric Stomach - Anatomy & Physiology|ventral mesogastrium]] in the embryo. The bile duct runs within the '''hepatoduodenal ligament'''.
-**At a point between the right kidney and pelvic inlet it turns medially and cranially around the root of the mesentry to become the ascending duodenum. The point of turn is called the ''caudal flexure'' of the duodenum.
-**The ascending duodenum is shorter and bends ventrally to enter the mesentery and becomes the jejunum.
-*Mesoduodenum attaches the duodenum to the dorsal abdominal wall. This is relatively short in the horse and ruminant and longer in the carnivore and pig.
 ==Vasculature==
-*The duodenum recieves blood from:
+The duodenum receives blood from the '''coeliac artery''' and the '''cranial mesenteric artery'''. Both are branches of the aorta. The '''cranial mesenteric vein''' drains blood from the duodenum into the '''portal vein'''. This blood, carrying the products of digestion, enters the [[Liver - Anatomy & Physiology|liver]].
-**Coeliac artery
-**Cranial mesenteric artery
-*Both are branches of the aorta.
-*The cranial mesenteric vein drains blood from the duodenum into the portal vein.
-**This blood, carrying the products of digestion, enters the liver.
-==Histology==
+==Species Differences==
-[[Image:electronmicrographduodenum.jpg|thumb|right|150px|Electron Micrograph Duodenum - Copywright RVC 2008]]
+===Canine===
-[[Image:caudalduodenum.jpg|thumb|right|150px|Caudal Duodenum (cat) - Copywright RVC 2008]]
+The duodenum is about 25cm long in canine species. The mesoduodenum is relatively long.
-*The mucosa is arranged into '''villi''' that provide a large surface area for absorption.
-*Epithelium is simple columnar - ideal for absorption.
-**Epithelial cells are known as enterocytes.
-**A single layer of enterocytes overlies the lamina propria.
-**Enterocytes originate from progenitor cells that migrate from mucosal crypts. They differentiate as they migrate up the villus.
-**Enterocytes ane absorptive and posses microvilli.
-*Membrane bound enzymes and transport proteins are also within the epithelium.
-*Each villus houses capillaries that transport amino acids, monosaccharides and other digestive products and lacteals that transport triacylglycerides. Lacteals drain into the lymphatic system.
-*'''Crypts''' are present at the base of each villus in the mucosa. Cell types in mucosal crypts (from luminal to basal):
-**''goblet''  at the tip of the crypt. Produce mucous by exocytosis.
-**''entero-endocrine''  in the middle of the crypt. Secrete peptides and amines.
-**''paneth''  at the base of the crypt. Function unknown. Contain eosinophilic granules.
-*'''Brunner's glands''' are present in the submucosa.
-**Produce an alkaline secretion which neutralises stomach acid.
-**Open into the crypts above in the mucosa.
-*Lamina muscularis is smooth muscle.
-**Contraction of smooth muscle shortens the villus. This helps to pump out absorbed products of digestion. Relaxation of smooth muscle lengthens the villus which increases surface area, facilitating absorption.
+===Equine===
+The mesoduodenum is relatively short, so the duodenum is closely tethered in a constant position. The descending duodenum is attached to the base of the [[Caecum - Anatomy & Physiology|caecum]]. The descending duodenum runs caudally beneath the [[Liver - Anatomy & Physiology|liver]] to the caudal pole of the right kidney where it has it's caudal flexure to become the ascending duodenum.
-==Species Differences==
+===Ruminant===
+The mesoduodenum is relatively short. The first part of the descending duodenum rises almost vertically within the ribcage, in close apposition to the liver. It turns level with the tuber coxae. The first part of the duodenum is attached to the [[Liver - Anatomy & Physiology|liver]] by the lesser omentum. The descending duodenum also provides attachment for the superficial and deep sheets of the greater omentum.
+===Porcine===
+The small intestine is comparable to the dog. The mesoduodenum is relatively long.
 ==Links==
+'''Click here for more information on the [[Intestines, Small and Large - Pathology| Pathology of the Small and Large Intestine]]'''
+{{Template:Learning
+|flashcards = [[Duodenum - Anatomy & Physiology - Flashcards|Duodenum anatomy]]
+|videos = [[Video: Ruminant small and large intestine potcast|Ruminant small and large intestine potcast]]<br>[[Video: Ruminant abdomen potcast|Ruminant abdomen potcast]]<br>[[Video: Foal gastrointestinal tract potcast|Foal gastrointestinal tract potcast]]<br>[[Video: Lateral view of the feline thorax and abdomen potcast|Lateral view of the feline thorax and abdomen potcast]]<br>[[Video: Female dog abdomen dissection|Female dog abdomen dissection]]<br>[[Video: Abdominal viscera of the horse dissection|Abdominal viscera of the horse dissection]]<br>[[Video: Equine left-sided abdominal and thoracic topography dissection|Equine left-sided abdominal and thoracic topography dissection]]<br>[[Video: Equine left-sided abdominal and thoracic topography dissection 2|Equine left-sided abdominal and thoracic topography dissection 2]]<br>[[Video: Ovine large and small intestine dissection|Ovine large and small intestine dissection]]<br>[[Video: Porcine abdomen dissection|Porcine abdomen dissection]]
+|Vetstream = [https://www.vetstream.com/canis/Content/Technique/teq00187.asp Cholecystoenterostomy]
+}}
+==Webinars==
+<rss max="10" highlight="none">https://www.thewebinarvet.com/gastroenterology-and-nutrition/webinars/feed</rss>
+[[Category:Small Intestine - Anatomy & Physiology]]
+[[Category:A&P Done]]