Chapter 6 DIGESTION ABSORPTION §l.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)
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)
r5 (T) LO mV 0(P) -35 70- Electrical activities contraction of digestive smooth muscles
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
• 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
U八Rn 黏膜层 點膜肌层 黏摸下层和 环形肌层 肌间神经丛 纵形肌层 传入纤维 浆膜层 交感神经 节后纤维 @ 脊髓传入纤维 迷走神经传入 Intrinsic 和传出纤维 (or enteric) nervous 齐0讲耀 system
Intrinsic (or enteric) nervous system
副交感神经系统 一一一一一交感神经系统 迷走神经 胸段 腹腔神经节 肠系膜下 腰段 神经节 骶段 Extrinsic nervous system
Extrinsic nervous system
2.Digestion in the mouth esophagus ●Saliva&its function Nature Composition of saliva pH6.6~7.1,99%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
§ 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
• 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
收缩波 舒张 Peristalsis of the esophagus
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 (HCI) Secreted by parietal cells Basic secretion:0~5 mmol/h Max secretion:20~25 mmol/h Mechanism of HCI secretion Functions:see next page
§ 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 Functions: see next page
60 0 30 10 0 0.5 1.0 1.5 壁细胞数(10细胞) Relationship between max volume of HCl secretion the number of parietal cells
Relationship between max volume of HCl secretion & the number of parietal cells