消化与吸收——生理课件.pptVIP

* Chapter 6 DIGESTION ABSORPTION § 1. Introduction ? Concept of digestion absorption * Mechanical chemical digestion ? Characteristics of digestive smooth muscles * General characteristics * Electrophysiological characteristics Resting potential (RP) Slow wave or basic electrical rhythm (BER) Action potential (AP) Electrical activities contraction of digestive smooth muscles ? Secretion of digestive glands * Main functions of digestive fluids ? Gastrointestinal innervation * Intrinsic (or enteric) nervous system Submucosal myenteric plexus * Extrinsic nervous system Parasympathetic sympathetic nerves ? Gastrointestinal hormones * General functions * Brain-gut peptides Intrinsic (or enteric) nervous system Extrinsic nervous system § 2. Digestion in the mouth esophagus ? Saliva its function * Nature Composition of saliva pH 6.6~7.1, 99% water Salivary amylase, lysozyme, salt, etc. * Functions of saliva Moisten the cavity solve food; keep the mouth clean; anti-bacteria; digest starch * Regulation of salivary secretion Pure neuroregulation Conditioned unconditioned reflex ? Mastication or chewing its effects * Definition * Effects Break up large food particles; mixes the food with saliva; aid swallowing ? Deglutition or swallowing * Definition * Process 1st, 2nd 3rd phase Peristalsis lower esophageal sphincter Peristalsis of the esophagus § 3. Digestion in the stomach ? Gastric juice its secretion * Nature, Compositions functions pH 0.9~1.5, colorless, 1.5~2.5 L/day Hydrochloric acid (HCl) Secreted by parietal cells Basic secretion: 0~5 mmol/h Max secretion: 20~25 mmol/h Mechanism of HCl secretion