NTDT200 Lecture Notes - Lecture 3: Pylorus, Pancreatic Juice, Chyme
6 Jan 2018
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Chapter 3: digestion, absorption and transport: digestion: process of breaking down food into nutrients that can be absorbed. Mouth: digestion begins here, crushing, mixing with fluids (ex: saliva, beverages, fluid from foods) Saliva protects teeth and lining of mouth, esophagus and stomach. Saliva contains water, mucus, salts and salivary amylase. Salivary amylase: starts process of breaking down carbohydrates. Esophagus: swallowed food called bolus, upper esophageal sphincter. Stomach: bolus transferred little by little into lower portion of stomach, food ground to semiliquid chyme, mixes with gastric juices. Hydrochloric acid (uncoils proteins: mucus protects stomach walls, pyloric sphincter regulates time in stomach and prevents backflow. Small intestine: duodenum, jeiunium and ileum (~10 feet) Surface area of tennis court: major site for absorption. Digestive secretions: pancreatic enzymes target all 3 macronutrients, pancreatic juice contains bicarbonate > reduces acidity of chyme as it enters small intestine, bile.
