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32 terms

Digestion

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Digestion
Four stages: Ingestion, Digestion, Absorption, Egestion
Tongue
Functions: Helps position food in mouth; roll food into bolus; mixes food with saliva, has taste buds
Salivary Glands
Produce saliva which contains amylase.
Amylase
Enzyme for digesting starches into disaccharides. Hint: found in saliva.
Esophagus
Leads from pharynx to stomach. covered with mucus along inner surface. composed of circular and longitudinal muscles. Pushes food down through peristalsis.
LES (Lower Esophageal Sphincter)
control entrance of food into stomach.
Stomach (first part)
pH of 2-3. Inner wall folded into ridges called RUGAE (to increase surface area). Has about 40 mil cells lining interior. secrets 2-3 L of gastric juice/day.
Gastric juice
Contains HCl pepsinogen, mucus and gastrin. Hint hint.
Pepsin
Breaks down proteins proteins into long chain polypeptide. Activated form of pepsinogen (activated by HCl, inactivated by HCO3- ions).
Chyme
Partly broken down food
Renin
an enzyme that coagulates milk proteins in the stomach (to permit more time to digest milk)
Gastrin
Hormone that increases gastric secretions when partially digested proteins appear in the stomach or when the stomach distends.
Pyloric Sphincter
Control food's entry into small intestine. _______ sphincter.
Small intestine
Food passes from stomach into this. Site of absorption as well as a majority of digestion. About 5.5 to 6 meters long and attached to rear of abdomen by membrane called mesentary.
Duodenum
Makes up first 25-30 cm of small intestine. Hint: comes before jejunum; and ileum. This part of intestine operates at pH of about 9.0.
Secretin
released when acidic materials enter the small intestine. Stimulates pancreas to release HCO3- ions (bicarbonate ions). Heavily stimulated to be released by high acidity in chyme.
Gastric Inhibitory Peptide; GIP; Enterogastrone
Inhibits gastric secretions; slows motility in the stomach. Most strongly stimulated to be released with a high fat content in chyme; enables fatty meals to remain in stomach longer than non-fatty meals
Erepsin
Converts peptones (short chain peptides) into amino acids. Produced in the duodenum and pancreas.
Disaccharases
Convert disaccharides into monosaccharides. Produced in the duodenum.
Enterokinases
Activates trypsin from pancreas. Converts trypsinogen into trypsin. Produced in the duodenum.
Villi
To increase the surface area in the stomach, the small intestine is folded into _________;
Microvilli
Villi have cell membranes that have finger-like projections called _____
Lacteals (lymph vessels)
Absorb fatty acids/ and glycerol.
Capillary network
Absorb monosaccharides and amino acids.
CCK (cholecystokinin)
Form the small intestine (when fats are present). Stimulates increased pancreatic secretions of digestive enzymes and gall bladder contractions.
Gall bladder
Stores and injects bile into the duodenum.
Bile
Physically, digests fats to increase surface area for lipases to act on chemically.
Pancreas
Produce trypsinogen Erepsin, Amylase and Lipases.
LIver
Produce bile to emulsify fats Stores glycogen; detoxify blood; deaminates proteins; stores vitamins A, D, B12; manufactures proteins for blood clotting and vitamins.
Large Intestine
Site of Reabsorption.
Rectum
Stores solid waste (feces).
Colon
Last part of the large intestine. Cancer of this part is caused by prolonged storage of waste.When contacted by waste, it has receptors that initiate bowel movement.