STOMACH:
The stomach is an enlarged segment of the digestive tract in the left superior part of the abdomen immediately below the diaphragm.Typically j shaped when empty.The opening from the esophagus into the stomach is the cardiac opening(located near the heart).The cardiac sphincter surround the cardiac opening.Although this is an important structure in the normal function of the stomach it is a physiologic constrictor only and cannot be seen anatomically.The largest part of the stomach is body which narrows to form the pyloric region,that joins the small intestine. The opening between the stomach and small intestine is the pyloric opening, which is surrounded by a relatively thick ring of smooth muscel called the pyloric sphincter. Stomach wall consist of following layers
1-serosa(outermost)
2-muscularis(composes of longitudenal layer, circular layerand oblique layer)
3-submucosa
4-mucosa
The stomach is lined with simple columnar epithelium. The mucosal surface forms numerous tube like GASTRIC PITS which are opening for the gastric gland. The epithelial cells of the stomach can be devided into four main types. The first type is SURFACE MUCOUS CELLS, which produce mucous, is on the surface and lines the gastric pit.The remaining three are in the gastric gland. They are
1- Parietal(oxyntic)cells(produces HCL and intrinsic factor)
2-Principle cell(secrete pepsinogen)
3-Endocrine cells(secrete the harmone gastrin into the blood)
Intrinsic factor is a glycoprotein that bind with vitamin B12 and make the vitamin more reasilly absorbed in the ileum(which is a part of small intestine)
FUNCTIONS OF STOMACH:
1-Storage of food
2-Protein digestion begin but not end
3-secretion of HCL(which kill germs that enter from mouth)
4-absorption of certain substances(water,sugar,alcohol)
The smooth muscles of the stomach produce contractions known as MIXING WAVES. The mixing wave mix the boluses of food with gastric juice. This mixing leads to the formation of thick liquid known as CHYME(meaning juice)
The low ph of stomach also stops carbohydrate digestion by inactivating salivary amylase. The low PH also denatures many protein so that proteolytic enzymes can reach internal peptide bond, and it provide the proper envirment for the function of PEPSIN
Pepsin catalyzes the cleavage of some covalent bond in proteins, breaking them into smaller peptide chain
HCL changes Fe3+ to Fe2+
The stomach is an enlarged segment of the digestive tract in the left superior part of the abdomen immediately below the diaphragm.Typically j shaped when empty.The opening from the esophagus into the stomach is the cardiac opening(located near the heart).The cardiac sphincter surround the cardiac opening.Although this is an important structure in the normal function of the stomach it is a physiologic constrictor only and cannot be seen anatomically.The largest part of the stomach is body which narrows to form the pyloric region,that joins the small intestine. The opening between the stomach and small intestine is the pyloric opening, which is surrounded by a relatively thick ring of smooth muscel called the pyloric sphincter. Stomach wall consist of following layers
1-serosa(outermost)
2-muscularis(composes of longitudenal layer, circular layerand oblique layer)
3-submucosa
4-mucosa
The stomach is lined with simple columnar epithelium. The mucosal surface forms numerous tube like GASTRIC PITS which are opening for the gastric gland. The epithelial cells of the stomach can be devided into four main types. The first type is SURFACE MUCOUS CELLS, which produce mucous, is on the surface and lines the gastric pit.The remaining three are in the gastric gland. They are
1- Parietal(oxyntic)cells(produces HCL and intrinsic factor)
2-Principle cell(secrete pepsinogen)
3-Endocrine cells(secrete the harmone gastrin into the blood)
Intrinsic factor is a glycoprotein that bind with vitamin B12 and make the vitamin more reasilly absorbed in the ileum(which is a part of small intestine)
FUNCTIONS OF STOMACH:
1-Storage of food
2-Protein digestion begin but not end
3-secretion of HCL(which kill germs that enter from mouth)
4-absorption of certain substances(water,sugar,alcohol)
The smooth muscles of the stomach produce contractions known as MIXING WAVES. The mixing wave mix the boluses of food with gastric juice. This mixing leads to the formation of thick liquid known as CHYME(meaning juice)
The low ph of stomach also stops carbohydrate digestion by inactivating salivary amylase. The low PH also denatures many protein so that proteolytic enzymes can reach internal peptide bond, and it provide the proper envirment for the function of PEPSIN
Pepsin catalyzes the cleavage of some covalent bond in proteins, breaking them into smaller peptide chain
HCL changes Fe3+ to Fe2+
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