BIO 208 Lecture Notes - Lecture 5: Muscular Layer, Soft Palate, Sensory Analysis
Document Summary
1: mechanical processing, digestion: chemical breakdown of food to absorbable bits, secretion: release of water, enzymes, acids, and buffers, absorption: movement of organic/inorganic bits into body, excretion, non speci c immunity, homeostasis. Processing of food: oral cavity, tongue and teeth. Lubrication and digestive secretions - salivary amylase-ptyalin. Oral phase: elevation of soft palate and movement of bolus into nasopharynx. Pharyngeal phase: initiation of involuntary swallowing re ex and closure of epiglottis. Sequential waves of contraction force food down the gi tract. Circular muscles behind bolus contract moving food forward and preventing back ow. Contraction waves of circular muscle propel food: segmentation. No propulsive force (no pattern of contraction) Bolus of food passes lower esophageal sphincter > enters the stomach for further processing: mechanical breakdown of food items, temporary storage of food, chemical breakdown of proteins, production of intrinsic factor (vit b12 uptake) Simple columnar e. t: cells of gastric pits. Communicates with gastric glands: gastric glands, parietal cells.
