Anatomy and Physiology Digestive System Ch. 25
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44 terms
Terms | Definitions |
|---|---|
 mechanical digestion | the physical breakdown of food, and still maintains same chemical properties |
| chemical digestion | the chemical breakdown of food; changes the chemical of food through acids enzymes etc.; breakdown of polymers to monomers |
| accessory organs | teeth, tongue, salivary glands, liver, gallbladder, and pancreas; not part of the GI tract |
| mucosa | epithelium,, lamina propria, muscularis mucosae |
| submucosa | layer of tissue that is vascular and holds digestive glands |
| muscularis externa | inner circular layer and out longitudinal layer |
| serosa | areolar tissue, mesothelium; these layer help with peristalsis |
| enteric nervous system | in the esophagus, stomach and intestines, they regulate digestive tract motility, secretion and blood flow; regarded as part of autonomic nervous system |
| submucosal plexus | part of the enteric nervous system and is found near submucosa, controls secretions of submucosal glands and controls muscularis mucosae contractions |
| myenteric plexus | part of the enteric nervous system and is found between layer of muscularis externa; controls parastalsis |
| mastication | the act of the mouth that hastens of facilitates digestion, when food touches the mouth it triggers chewing reflex; chewing exposes more surface area for saliva with enzymes to reach |
| mastication muscles | buccinator, tongue, and orbicularis oris |
| digastric muscles | opens the mouth and connects to the bottom of the mandible |
| temporalis | prime mover of closing mandible |
| masseter | synergist for closing the mouth |
| pterygoids | side to side chewing |
| saliva | mostly water and a hypotonic solution; contains amylase which breakdown starches, mucus, which binds and lubricates food bolus, electrolytes like salts, phosphate and bicarbonate, lysozyme, IgA which is an antibacterial, and lingual lipase an enzyme that begins fat digestion in the mouth |
| intrinsic salivary glands | lingual, labial, and buccal glands and secrete saliva at a fairly constant rate |
| extrinsic salivary glands | parotid (mumps), submandibular, sublingual glands |
| esophagus | non-keratinized stratified squamous, consist of cardiac orfice and lower esophageal sphincter, which prevents stomach contents from regurgitating |
| chyme | in the stomach and is food broken down in to liquid substance |
| know anatomy of the stomach | know anatomy of the stomach and that stomach wall is simple columnar epithelium and that the stomach muscles mixes chyme |
| mucous cells | the cells int he stomach that lubricate and protects stomach lining |
| regenerative cells | stomach cells that regenerate the stomach lining |
| parietal cells | cells in the stomach that are most important; they secrete hydrochloric acid and intrinsic factor, the stomach cannot absorb B12 w/o this factor and a lack of it can cause pernicious anemia |
| lamina propria | int he stomach lining and contain glands that secrete into gastric pits, they secrete mucus |
| chief cell | secretes pepsinogen, which is the inactive form of pepsin, a protease; secretes gastric lipase, which breaks down lipids in food |
| enterendocrine cell (G cell) | secrete gastrin, which enhances gastric secretion |
| gastric secretions | parietal cell contains carbonic and hydrase, so it can use carbon dioxide and can convert it in the presence of water to carbonic acid. this is the result of the bicarbonate and the H+. H+ is pumped out by antiporter and K+ is pump in, this is the H+-K+ ATPase; bicarbonates are exchanged for Cl- from the blood plasma, this is called chloride shift. CL- is pumped into lumen in gastric gland to join H+ making hydrochloric acid |
| alkaline tide | the blood leaving the has higher pH when digestion is occurring because the bicarbonate accumulates in the blood when stomach produces HCl |
| HCl | responsible for cleaving pepsinogen and turning it into pepsin which is the active form of pepsinogen; activation lingual lipase, which is secreted in saliva; liquifies food and forms chyme; takes Fe3 and turns it into Fe2, a form of iron that can be absorbed ans used for hemoglobin synthesis; acts as antibacterial, which doesnt kill H. pylori |
| pancreas | an endocrine gland in which it secretes insulin and glucogen into the blood; an exocrine gland that secretes pancreatic juice, which is water, enzymes, zymogens, and sodium bicarbonate |
| pancreatic acinar cell | produce zymogens, which is an inactive enzyme and are activated into proteases. also secrete pancreatic amylase, which breaks down starch, lipase, whichh breaks down fat, DNase adn RNase |
| zymogens | inactive proteases like trypsinogen, chymotrypsinogen, procarboxypeptidase |
| activation of zymogens | trypsinogen is secreted into lumen and converted to trypsin by enterokinase. trypsin is autocatalytic and converts trypsinogen into still more trypsin; it also converts 2 other zymogens in order to digest dietary protein |
| small intestine | nearly all chemical digestion and nutrient absorption occurs here; has intestinal crypts |
| duodenum | first part of the small intestine that neutralizes stomach acids, emulsifies fats, and inactivates pepsin by pH increase, also has pancreatic enzymes |
| jejunum | part of the small intestine and most digestion and nutrient absorption occurs here |
| ileum | part of the small intestine and has villi, which contain blood vessels and lymphatic (lacteal), and microvilli , which have brush border cells that produce enzymes for final stages of digestion |
| carbohydrate digestion | salivary amylase stops working in the stomach because of pH, pancreatic amylase takes over and finishes starch digestion; brush border enzymes act upon oligosaccarides, maltose, sucrose, lactose and fructose |
| carbohydrate absorption | SGLT, a symport, absorbs galactose and help absorb glucose; fructose is absorbed by facilitated diffusion |
| protein digestion and absorption | pepsin becomes inactivated when passes into duodenum and mixes with pancreatic juice; pancreatic enzymes take over by hydrolyzing polypeptide into shorter oligopeptide; brush border enzymes finish by producing amino acids that are absorbed in to epithelial cells; amino acids move into cell by cotransporter amino acids move to blood stream by facilitated diffusion |
| fat digestion and absorption | broken down by emulsifying properties of bile, like lecithin and bile acids, this exposes the chyme to more surface area of the pancreatic lipases, the lipases cleave triglycerides into 2 free fatty acids and a monoglyceride; micelles in bile, which have a phospholipid and cholesterol core, transport lipids to intestinal epithelium, the lipids diffuse into cell and are reassembled into tryglycerides in the smooth ER, from here they are packaged into chylomicrons adn are exocytosed adn are absorbed by lacteal villus |
| large intestine histology | had mucosa, which is simple columnar and a canal of stratified squamous, lots of intestinal crypts which produce mucus and are glands sunken into lamina propria; muscularis externa has longitudinal muscle fibers (concentrated in the taeniae coli) and form pouches (haustra) |
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