HPED 2507 Lecture 5: Digestive System
6 Oct 2016
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Document Summary
Human body is composed of trillions of cells organized into tissues, organs and body systems. Human beings are in a continual state of renewal: bones, heart and blood vessels, and nerves. Each day 5% of our body weight is replaced by new tissue. Intestinal tract lining cells replaced every 3 days. Skin cells and red blood cells replaced every 10-120 days. After a meal your brain and hormones coordinate the digestive system to digest and absorb food. Digestion break food down into its components see def"n pg 77: mechanical aspects. Chewing, muscular action of gi tract: chemical aspects. Complete when cho, pro & fat reduced to sub that can be absorbed, & when vitamins and mineral are released. Chewing: breaks down large molecules and adds saliva. Peristalsis: wavelike muscular contractions of the gi tract that push contents along. Stomach action: circular, longitudinal & diagonal muscles chyme released 3 times/min into intestine.
