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[r0cinante] Biological Systems

Key Concepts:

Terms in this set (177)

1. mastication- chewing with incisors, cuspids, molars
2. saliva- salivary amylase which hydrolyzes starch to disaccharides, lingual lipase which digests fat, lysozyme which attack bacterial cell walls
3. bolus- ball of digested food

1. pharynx- throat, has openings to trachea and esophagus
2. epiglottis- cartilage flap to cover up trachea
3. upper esophageal sphincter- muscular ring at top
4. lower esophageal sphincter- muscular ring near stomach

1. acidity- gastric pH is 2 due to HCl secretion by parietal cells, functions: destroys microorganisms, acid-catalyzed hydrolysis of proteins, converts pepsinogen to pepsin, can also denature important proteins like antibodies!
2. pepsin- pepsinogen (zymogen) is secreted by chief cells and converted to pepsin, catalyzes proteolysis
3. motility- churns food, creates chyme (food + secretions)
4. pyloric sphincter- regulates food entering duodenum, cholecystokinin is hormone that signals to close it
5. gastrin- G cells secrete this hormone that stimulate acid and pepsin secretion, histamine binds to parietal cells to stimulate acid secretion

small intestine (wall):
1. villi- multicellular projections that make up brush border
2. hepatic portal vein- villi have capillaries that connect
3. lacteals- lymphatic vessels to absorb fat
3. Peyer's patches- lymphocytes to monitor for pathogens
4. 3 segments: duodenum, jejunum, ileum

small intestine (duodenum):
1. pancreatic duct- brings exocrine secretions (digestive enzymes) from pancreas
2. common bile duct- brings bile (waste vehicle, digest fat) from gallbladder
3. sphincter of Oddi- bile and pancreatic ducts empty here
4. duodenal enzymes- enterokinase (creates trypsin), brush border enzymes (hydrolyze disaccs/dipeps to monos)
5. duodenal hormones- cholecystokinin (to digest fat), secretin (to increase pH from stomach since duodenal pH must neutral), enterogastrone (to stop stomach emptying)

large intestine:
1. ileocecal valve- separate small intestine from large
2. function: absorb water and minerals, form feces
3. segments: cecum, appendix, rectum, anal sphincter
4. colonic bacteria- supply vitamin K, outcompete dangerous bacteria for space

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