Changes

==Introduction==

 

[[Image:Stomach Anatomy 1.jpg|thumb|right|150px|Stomach Anatomy 1 - Copyright Nottingham 2008]]

==Overview==

The enlarged swelling of the gastrointestinal tract between the [[Oesophagus - Anatomy & Physiology|oesophagus]] and [[Duodenum - Anatomy & Physiology|duodenum]] is called the stomach. It is a simple structure in carnivores and a compound structure in ruminants.

[[Image:Stomach Anatomy 1.jpg|thumb|right|250px|Stomach Anatomy 1 - Copyright Nottingham 2008]]

 

The enlarged swelling of the gastrointestinal tract between the '''[[Oesophagus - Anatomy & Physiology|oesophagus]]''' and the '''[[Duodenum - Anatomy & Physiology|duodenum]]''' is called the '''stomach'''. It is a simple structure in carnivores and a compound structure in ruminants.

The stomach functions as a reservoir of food where digestion occurs through chemical and mechanical processes. This allows food to be broken down further and absorbed.

The stomach functions as a reservoir of food where digestion occurs through chemical and mechanical processes. This allows food to be broken down further and absorbed.

==Development==

==Development==

*The gut tube is formed from the folding of splanchnopleure (mesoderm and endoderm)

The '''gut tube''' is formed from the folding of the '''splanchnopleure''' (mesoderm and endoderm). The '''mesoderm''' forms the skeletal muscle, ([[Oesophagus - Anatomy & Physiology|oesophagus]] and [[Anus - Anatomy & Physiology|anus]]), smooth muscle (lateral plate mesoderm) and connective tissue layers form around the inner '''endoderm'''. The '''endoderm''' is the inner layer forming the epithelia and glands.

 

*The mesoderm forms the skeletal muscle ([[Oesophagus - Anatomy & Physiology|oesophagus]] and [[Anus - Anatomy & Physiology|anus]]), smooth muscle (lateral plate mesoderm) and connective tissue layers around the inner endoderm.

 

*The endoderm is the inner layer forming the epithelia and glands.

 

 

 

 

 

5. The dorsal mesogastrium becomes elongated (with the [[Spleen - Anatomy & Physiology|spleen]]) and expands into a large fold along the ventral abdominal wall. This becomes the greater omentum which covers all the abdominal organs. It is a superficial structure which is free to move.

6. The ventral mesogastrium becomes the lesser omentum. It is in between the stomach and the [[Liver - Anatomy & Physiology|liver]]. The rest of the ventral mesentry degenerates.

The region enlarges. Swelling indicates where the stomach will form. The dorsal surface becomes convex to form the '''greater curvature''' of the stomach and the ventral surface becomes concave to form the '''lesser curvature'''. Two rotations of 90 degrees occur along the longitudinal axis and then then the dorso-ventral axis. The dorsal '''mesogastrium''' becomes elongated (with the [[Spleen - Anatomy & Physiology|spleen]]) and expands into a large fold along the ventral abdominal wall. This becomes the '''greater omentum''' which covers all the abdominal organs. It is a superficial structure which is free to move. The '''ventral mesogastrium''' becomes the '''lesser omentum'''. It is in between the stomach and the [[Liver - Anatomy & Physiology|liver]]. The rest of the ventral mesentry degenerates.

[[Image:Stomach Anatomy 2.jpg|thumb|right|150px|Stomach Anatomy 2 - Copyright Nottingham 2008]]

[[Image:Stomach Anatomy 2.jpg|thumb|right|250px|Stomach Anatomy 2 - Copyright Nottingham 2008]]

==Structure and Function==

==Structure and Function==

*Stomach split into regions: cardia, fundic, body and pyloric parts

The stomach is split into the regions: '''cardia''', '''fundic''', '''body''' and '''pyloric''' parts. The entire stomach is motile. It has a pH of 0.9 to 1.5.

 

*Entire stomach is motile

 

*pH 0.9 to 1.5

 

 

*The smaller part of the stomach has thicker walls and passes to the right of the midline into the [[Duodenum - Anatomy & Physiology|duodenum]] at the pyloric sphincter.

 

 

 

 

 

 

 

 

*The empty stomach lies completely within the rib cage and does not contact the abdominal floor. Little secretion is produced and only small peristaltic contractions occur.

The larger part of the stomach lies to the left of the midline, under cover from the ribcage and in contact with the [[Liver - Anatomy & Physiology|liver]] and diaphragm. The [[Oesophagus - Anatomy & Physiology|oesophagus]] opens into it at the cardiac sphincter. The smaller part of the stomach has thicker walls and passes to the right of the midline into the [[Duodenum - Anatomy & Physiology|duodenum]] at the pyloric sphincter. The angular point between the two parts of the stomach is called the '''angular notch''' (incisura)

[[Image:Stomach Anatomy 3.jpg|thumb|right|250px|Stomach Anatomy 3 - Copyright Nottingham 2008]]

*Once food is offered or anticipated, secretions begin

The '''fundus''' is a blind dome rising above the cardia; The '''body''' extends from the cardia ventrally; The '''pyloric''' part is on the right divided into a more muscular and a less muscular half. The '''serosa''' (external peritoneum) covers the entire organ.

Contractions start near the '''cardia''' and spread distally, accelerating and becoming more vigorous as they reach the '''pylorus''' region. The '''pyloric sphincter''' is open for 1/3 of the time during contractions. The empty stomach lies completely within the rib cage and does not contact the abdominal floor. Little secretion is produced and only small peristaltic contractions occur. Once food is offered or anticipated, the secretions begin.

**Gastrophrenic ligament- from the greater curvature of the stomach to the crura of the diaphragm

**Lesser omentum- connecting the lesser curvature of the stomach and the initial segment of [[Duodenum - Anatomy & Physiology|duodenum]] to the [[Liver - Anatomy & Physiology|liver]] in the region of the hepatic porta

**Gastrosplenic ligament- connecting the greater curvature of the stomach to the [[Spleen - Anatomy & Physiology|spleen]] by a double fold of peritoneum

**Greater omentum- connceting the greater curvature of the stomach to the [[Duodenum - Anatomy & Physiology|duodenum]] and dorsal body wall

==[[Stomach - Histology|Histology]]==

The stomach is supported by 4 folds of peritoneum; The '''Gastrophrenic ligament'''- from the greater curvature of the stomach to the crura of the diaphragm; The '''Lesser omentum'''- connecting the lesser curvature of the stomach and the initial segment of [[Duodenum - Anatomy & Physiology|duodenum]] to the [[Liver - Anatomy & Physiology|liver]] in the region of the hepatic porta; The '''Gastrosplenic ligament'''- connecting the greater curvature of the stomach to the [[Spleen - Anatomy & Physiology|spleen]] by a double fold of peritoneum and the '''Greater omentum'''- connceting the greater curvature of the stomach to the [[Duodenum - Anatomy & Physiology|duodenum]] and dorsal body wall.

==Vasculature==

==Vasculature==

[http://stream2.rvc.ac.uk/Anatomy/swine/Pig_abdomen.mp4 The Porcine Abdomen]

[http://stream2.rvc.ac.uk/Anatomy/swine/Pig_abdomen.mp4 The Porcine Abdomen]

 

[[Category:Stomach - Anatomy & Physiology]]

[[Category:Stomach - Anatomy & Physiology]]

[[Category:To Do - A&P]]

[[Category:To Do - A&P]]