Chapter 14 - Gastrointestinal Tract
The gastrointestinal tract takes in food, digests and absorbs nutrients, and eliminates the remaining waste material. It is divided into four regions: the esophagus, stomach, small intestine and large intestine.
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Stomach
The stomach digests food by acidification and the breakdown of proteins. It is divided into three histological regions (cardiac, body/fundus and pyloric) on their anatomical location and appearance of their glands.
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Fundic Stomach
Gastric glands are found in the fundus/body of the stomach and produce stomach acid and secrete proteolytic enzymes.
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(stimulated) |
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(unstimulated) |
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(enteroendocrine cell) |
Pyloric Stomach
Pyloric glands are located in the antrum of the pyloris.
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Gastroduodenal Junction
The gastroduodenal junction is the boundary between the stomach and the duodenum of the small intestine.
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Small Intestine
The small intestine is involved in the digestion of food and nutrient absorption. It is divided into the duodenum, jejunum and ileum.
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(villi) |
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(villi) |
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(villi) |
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(villi) |
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(epithelium) |
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(epithelium) |
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(epithelium) |
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(epithelium) |
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(intestinal crypt or intestinal crypt of Lieberkühn) |
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(intestinal crypt or intestinal crypt of Lieberkühn) |
Gut-Associated Lymphoid Tissue (GALT)
Lymphoid nodules become increasingly numerous in the ileum and form bulges called Peyer’s patches. M cells in the epithelium overlaying Peyer’s patches and transport antigenic material to the underlying lymphocytes.
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Ileocecal Junction
The ileocecal junction is the boundary between the small intestine and the large intestine.
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Large Intestine
The large intestine absorbs water and consolidates the fecal mass. It is divided into the cecum, appendix, colon, rectum and anal cannal.
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