BIO 1109 Lecture Notes - Lecture 5: Gastrointestinal Tract, Starch, Epiglottis
18 Oct 2015
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Document Summary
There are 2 stages of digestion. a)mechanical digestion-physically breaking up large chunks into small bits (chewing), then mixing it up b)chemical digestion- digestive enzymes called hydrolases act on food polymers and break them into monomer units. 3. absorption-monomer units move into the blood & are transferred throughout the body The whole wall is composed of smooth muscle. The inside surface is exposed to the environment. 1. mechanical digestion-breaks up food and mixes it with saliva. 2. chemical digestion-amylase hydrolyzes starch into the disaccharide maltose. Tongue-mixes and shapes food into a ball for swallowing. Esophagus-tube with 2 layers of smooth muscle in wall. Peristalsis-rhythmic contraction to move food through digestive tract. Sphincters are rings of muscle that control flow through the tube. Muscular sac with an extra 3rd layer of muscle. Inner lining(epithelium) is wrinkled-contains gastric glands which secrete gastric juice. Gastric glands produce- hydrochloric acids which activates pepsin-pepsin is the enzyme which hydrolyzes proteins into small polypeptides.
