Lecture 6 - (long chains of amino acids) to shorter chains...

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Gastrointestinal System Complex polymers to simple nutrients Absorb nutrients with maximal efficiency Exclude anti-nutrients (bacteria, toxins, etc.) Food passing GI system is not “in” your body (English Channel) GI system accomplishes digestive process by: o Liquification-turn food into a watery solution so that enzymes break chemical bonds o In the mouth- liquification and mechanical disruption. Not necessary but speeds up the process. Salivary amylase begins digesting starches to simple sugars. o Food in mouth causes cells in stomach to produce hydrochloric acid (HCl) and muscles in stomach contract. HCl lowers pH of food from 7 to about 2. Kills bacteria, inactivates enzymes Low pH denatures proteins and unwind to disrupt 3D structure Activates pepsin: enzyme in the stomach that slices proteins
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Unformatted text preview: (long chains of amino acids) to shorter chains o Stomach muscle action mixes and emulsifies fats o large drops to small droplets that stay dissolved. o Exit of food from stomach to small intestine controlled by pylorous (pyloric sphincter) Exit of food SLOWED BY: 1. fiber and/or fat in the diet 2. Stress In small intestine, sodium bicarbonate (baking soda) from pancreas neutralizes stomach acid and brings mixture to neutral pH Bile (made in liver, stored in gall bladder) coats fat droplets and keeps them from re-forming large drops Specialized fat-digesting enzymes called lipases digest fats Bile absorbed and recycled back to the liver Starch is digested by pancreatic amylase to simple sugars. Protein molecules digested to amino acids by proteases...
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This note was uploaded on 10/19/2011 for the course KIN 110 taught by Professor Lass during the Spring '08 term at UMass (Amherst).

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