Nutrition Concepts !!Class Notes : September 13, 2013 September 13, 2013 !Digestion and Absorption !!- Digestion Review: !Saliva- helps dissolve food. Only particles in solution Portion of food after chewed- bolus What do we share with the digestion and absorption?- pharynx Food through esophagus through diaphragm Epiglottis stops food from going down air pipe. Air pipe- trachea !After diaphragm- Esophageal sphincter which prevent reflux !Stomach- muscular elastic, water enzymes and hydrochloric acid with PH of 2, super acidic Salivary enzymes work in that acidity? No What digestion occurs in the stomach as a result of hydrochloric acid- protein dissolve What protects the stomach? Mucus secreted by the cells of the stomach's wall pyloric sphincter after stomach !Major site of digestion- small intestine (ileum, duodenum, jejunum) Pancreas does what?- secrete insulin, glucose homeostasis, manufactures (digestive) enzymes and secretes to the duodenum through pancreatic duct, releases bicarbonate to neutralize acid chyme that enters the small intestine Hydrochloric acid from stomach is neutralized by bicarbonate in the pancreas !enzymes- ace Gastric lipase- fats from the stomach !Hydrolysis- addition of water to break down into smaller pieces !Liver- (digestion) manufactures bio salts which are emulsifiers for fat. Bring fat into suspension into the water so the enzymes can break them down Gall bladder removed- yes digests fat. Bio salts come from the liver, so can be directly delivered. But can’t store them anymore. Fat malabsorption- leads to diarrhea Prevents back flow !Appendix- Houses bacteria and lymph cells (plays a big part in our immune system) Large intestine- lower part of the intestine that finishes digestion. Absorbs water and minerals; passes waste (fiber, bacteria, and unabsorbed nutrients) alone with water to the rectum Bacterial fermentation !- Absorption: Date Sept 13, 2013 Class Nutrition Concepts Page OneSmall Intestine ! -majority of absorption - ten feet long - surface area !absorption techniques ! simple diffusion (high concentration to low concentration) (some nutrients such as water and small lipids cross into intestinal cells freely) ! facilitated diffusion (some nutrients such as the water-soluble vitamins are absorbed by facilitated diffusion. They need a specific carrier to transport them from one side of the cell membrane to the other. Alternatively, facilitated diffusion may occur when the carrier changes the cell membrane in such a away that the nutrients can pass through ! ACTIVE TRANSPORT= requires energy !!Small intestine- the folds increase surface area Villi each covered with microvilli Crypts- lie in between the microvilli Artery- bringing nutrients Veins- taking away !Depends on the size of the nutrient what happens to it Lymph (itself) = fluid similar to blood but doesn't have platelets or red blood cells Fat soluble vitamins- A, D, E, K !Lymphatic System- bypass liver and enter bloodstream closer to the heart !The Vascular System- ! Blood !Arteries- take blood from the heart Veins- takes blood to the heart !Capillaries- they take oxygens to the cells, and from intestines, pick up nutrients !Heart to arteries to capillaries to veins back to the heart (blood flow) !Goes through Hepatic Portal Vein what happens in the liver? filtration- detoxification because it goes back to the heart Page
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