Structure and Functions of Stomach
Stomach is a dilated portion of the alimentary tract
situated in the upper part of the abdomen
Continuous with oesophagus
Pyloric orifice ' pyloric sphincter
Opens into the duodenum
The curved right border is called the lesser curvature
The curved left border is called the greater curvature
The upper opening of the stomach into the oesophagus is guarded by a physiological sphincter called cardiac sphincter.
The parts of stomach
The part above the cardiac orifice ' fundus
The main part ' body
The lower part ' antrum
The opening into the duodenum guarded by the pyloric sphincter - anatomical sphincter ' increased number of circular muscle fibres
Walls of the stomach
adventitial layer peritoneum - extends beyond the greater curvature as the greater omentum
muscle layer outer longitudinal fibres, middle layer of circular fibres, an inner layer of oblique fibres
mucosa longitudinal folds of mucosa called rugae - disappear when the stomach is full. - gastric glands - gastric juice.
coeliac artery : right gastric artery, left gastric artery, right gastroduodenal artery, left gastroduodenal artery, short gastric arteries
venous drainage into the portal vein
sympathetic supply from coeliac plexus
parasympathetic supply from the vagus nerves
Temporary storage for food allowing time for the digestive enzymes to act
Chemical digestion - pepsin converts proteins to polypeptides
Mechanical digestion - the stomach contents are triturated and made into smaller particles chyme
Limited absorption of water, alcohol and some lipid soluble drugs.
Non-specific defence against microbes - by hydrochloric acid , vomiting
Helps iron absorption to be done in the small intestines.
Production of intrinsic factor needed for absoption of vitamin B12
Controlled release of the stored contents into the duodenum.
The Anatomical Relations of the stomach
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