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Digestive System (Mesentary and peritoneum (Mesentary-a double layer of…
Digestive System
Mesentary and peritoneum
Mesentary-a double layer of peritoneum from the body wall to the digestive organs. Holds organs in place, stores fat, provides a place for blood vessels and nerves.
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Mesocolon-connected to the transverse colon and sigmoid colon to the posterior wall of the abdominal cavity.
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Greater omentum-starts at the great curvature of the stomach and drapes over inferior organs. Attaches up over transverse colon to the posterior wall.
Intraperitoneal organs-located with in the peritoneum: stomach, liver, transverse colon, jejunum, ileum and sigmoid colon.
Retroperitoneal organs-not located with in the peritoneum: duodenum, pancreas, ascending colon, descending colon, rectum.
The Large Intestine, Rectum and Anal Canal
Large intestine-water and electrolyte absorption. Ileocecal valve stops contents of large intestine from backing up into small intestine.
Teniae coli are 3 longitudinal strips of muscle on the large intestine that contract pulling the large intestine into pouches called haustra. Epiploic appendages are little pieces of fat filled visceral peritoneum along the large intestine.
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Anal canal-has mucous glands for lubrication. Internal sphincter is smooth muscle innervated by the autonomic nervous system releases when feces is ready to be expelled. External sphincter is skeletal muscle which voluntarily expels feces when we decide.
Digestion
Mechanical-cut up the food with teeth, churning of the stomach and segmentation in the small intestine.
Chemical-also makes food smaller but does this using secreted enzymes found in saliva, stomach, and small intestine.
Movement of food
Peristalsis-another type of movement in the GI tract (from esophagus through the large intestine). Characterized by waves of contractions moving "food" through the tract
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The Stomach
Function-stores food, mechanically and chemically digests food.
Anatomy
parietal cells (glands) produce hydrochloric acid and produce intrinsic factor which is needed for the absorption of vitamin B12 which is needed to produce erythrocytes. Chief cells (glands) secrete pepsinogen which is activated by the HCl in the stomach. This activated form called pepsin breaks down proteins.
Cardiac sphincter-prevents the reflux of acid into the esophagus. Pyloric sphincter-regulates the amount of chyme moving into the small intestine.
The Small intestine
Function-mechanical digestion (segmentation), chemical digestion (enzymes) and absorption.
Anatomy
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duodenal glands-secrete alkaline mucus which neutralizes stomach acid and protects the lining of the small intestine.
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Major functions
Break down food into pieces small enough to be absorbed into the circulatory system. Eliminate what can't be broken down.
Major Structures
GI tract includes the "tube" from mouth to anus. Accessory organs include: salivary glands, liver (makes bile), gallbladder (stores bile) and the pancreas (secretes enzymes).
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