山东大学：《医学生理学 Medical Physiology》课程教学资源（PPT课件讲稿，人体生理学 Human Physiology）Chapter 6 Gastrointestinal Physiology Gastrointestinal Regulation and Motility Part IV Gastrointestinal Secretions

Chapter 32 Gastrointestinal Secretions

1 Chapter 32 Gastrointestinal Secretions

Exocrine of the Gi tract Composition Ingest 2 1/d Function Saliva 1.5ld water pH68-70 A. Digest food B. Dilute the food into iso- Gastric secretion 2 osmotic fluid ld,pH1.5-3 C. Provide a favorable pH for Bile 0.5 l/d ph ll 78-8.0 the digestive enzymes intestine Pancreatic Juice ab D. Provide mucus for 1.5 ml/d ph8.0-84 8.5ld Intestinal secretion 1.5 lubrication and protection ldpH78-8.0 Cole of all parts of the absorbs 0.4 alimentary tract 1 Id 0.1 l/d water Regulation ex excreted

2 Exocrine of the GI tract Composition Function A. Digest food B. Dilute the food into iso￾osmotic fluid C. Provide a favorable pH for the digestive enzymes D. Provide mucus for lubrication and protection of all parts of the alimentary tract Regulation Saliva 1.5 l/d pH 6.8-7.0 Ingest 2 l/d water Gastric secretion 2 l/d, pH 1.5-3 Bile 0.5 l/d pH 7.8-8.0 Pancreatic juice 1.5 ml/d pH 8.0-8.4 Intestinal secretion 1.5 l/d pH 7.8-8.0 Small intestine absorbs 8.5 l/d Colon absorbs 0.4- 1 l/d 0.1 l/d water excreted

I. Salivarysecretien

3 I. Salivary secretion

Salivary gland s Parotid gland Accessory parotid gland Parotid duct Sublingual gland Submandibular duct Submandibular gland

4 Salivary gland

Secretion Saliva: water, ions, mucus, enzmes Acinar Cells:腺 HCO Primary secretion is 泡细胞 plasmet like(isotonic) Acinus Acinar cells ∠ Kt Duct Ducts are relatively impermeable to wate Secretory duct cells H 5

5 Secretion Saliva: water, ions, mucus, enzymes Acinar Cells: 腺 泡细胞

Functions of secretion 1. Moisten food 2. Begin chemical digestion(a amylase, tE 粉酶) 3. Adjust appetite 4. Bacteriostatic action(抑菌作用 ( bacteriolysis,溶菌素)

6 Functions of secretion 1. Moisten food 2. Begin chemical digestion (a amylase, 淀 粉酶) 3. Adjust appetite 4. Bacteriostatic action （抑菌作用) (bacteriolysin, 溶菌素)

Control of salivary secretion Fear reflexes Nausea Sleep Secretion rate depends Tired Dehydration entirely on neural control Higher centers brai both parasympathetic(Ach, M receptor)(water Taste secretion) Salivatory nuclei Chew ing and sympathetIc (na,B srel-7G receptor)(enzyme) SNS (CAMP) PNS(P3) lead to increased Secretion secretion Vasodilation Acinus Duct Cell contraction Metabo|sm↑ Sal vary gland

7 Control of salivary secretion Secretion rate depends entirely on neural control both parasympathetic (Ach, M receptor) (water secretion) and sympathetic (NA, β receptor) (enzyme) lead to increased secretion Fear Sleep Tired Dehydration Nausea Secretion Vasodilation Cell contraction Metabolism SNS (cAMP) PNS(IP3)

I. Gastricsecretion

8 II. Gastric secretion

Functions of stomachy Temporary store of ingested material Dissolve food particles and initiate digestive process Control delivery of contents to small intestine Sterilise ingested material Produce intrinsic factor (vitamin B12 absorption)

9 • Temporary store of ingested material • Dissolve food particles and initiate digestive process • Control delivery of contents to small intestine • Sterilise ingested material • Produce intrinsic factor (Vitamin B12 absorption) Functions of Stomach

Oesophaqus Lower Oesophageal Sphincter Fundus Duodenum Pylorus Body 10 Antrum

10 Oesophagus Lower Oesophageal Sphincter Fundus Body Antrum Duodenum Pylorus