13 Lecture Outline: Digestive System Hole s HAP [Chapters 17 & 18] General Characteristics of the Alimentary Canal A. Functions 1. Ingestion 2. Mechanical digestion 3. Chemical digestion 4. Propulsion 5. Absorption 6. Defecation B. Components of Digestive system 1. Alimentary canal (GI tract) 2. Accessory organs C. Alimentary canal wall 1. Mucosa a. b. c. 2. Submucosa 3. Muscular layer
14 4. Serosa serous membrane adventitia D. Movements of the Tube E. Innervation of the Tube Submucosal plexus Myenteric plexus Parasympathetic Sympathetic Mouth A. Functions B. Parts of the Mouth 1. Cheeks and lips
15 2. Tongue papillae: 3. Palate o filiform o fungiform o circumvallate lingual frenulum Hard palate ankyloglossia 4. Tonsils Soft palate palatine lingual Uvula pharyngeal 5. Teeth Enamel Dentin Pulp cavity Dentition formula: 3 2 1 4 1 2 3 Molars Premolars Canines Incisors Secondary teeth
16 6. Salivary glands 3 pairs: a. Parotid b. Submandibular Pharynx A. Characteristics 3 divisions: Nasopharynx Oropharynx c. Sublingual secretions of the salivary glands: a. Parotid b. Submandibular c. Sublingual Saliva a. Components electrolytes, buffers, glycoprotein s, enzymes, wastes Laryngopharynx b. Functions moistens stimulates initiates
17 B. Swallowing Mechanism Soft palate, uvula, hyoid, larynx Epiglottis and closes off top of trachea Muscles: longitudinal muscle inferior constrictor muscles Peristaltic waves C. Deglutition bolus = 1. Buccal Esophagus A. Function o 2. Pharyngeal 3. Esophageal o B. Anatomy Esophageal hiatus Upper esophageal sphincter Lower esophageal sphincter C. Histology Mucosa Submucosa Muscular layer Adventitia
18 Stomach A. Functions 1. 2. 3. 4. B. Anatomy Features 4 regions: rugae: C. Gastric secretions 1. pepsinogen 2. pepsin 3. hydrochloric acid 4. mucus 5. intrinsic factor Gastric pits: Gastric glands: a) mucous cells b) chief cells c) parietal cells
19 D. Phases and regulation of gastric secretions Phases 1. Cephalic 2. Gastric 3. Intestinal Regulation of gastric secretions 1. 2. 3. 4. E. Gastric Activities Gastric Absorption Mixing & emptying Chyme = Rate of emptying: Enterogastric reflex F. Hormones Gastrin CCK (cholecystokinin) Secretin
20 Accessory Organs: Pancreas, Liver, and Gallbladder Pancreas A. Structure: head body tail pancreatic duct (Wirsung) hepatopancreatic ampulla hepatopancreatic sphincter B. Histology 1. Pancreatic acini 2. Pancreatic islets (Langerhans) a) Alpha cells BG levels b) Beta cells BG levels C. Pancreatic Juice pancreatic amylase pancreatic lipase trypsin, chymotrypsin, and carboxypeptidase nucleases bicarbonate ions D. Regulation of secretions
21 Liver A. Anatomy Lobes Ligaments Hepatic lobules Hepatic cells Hepatic sinusoids Kupffer cells Central veins B. Bile ducts and bile Bile ducts: right & left hepatic duct Composition of Bile: water bile salts o o bile pigments cholesterol electrolytes C. Liver Functions 1) CHO 2) Lipid 3) Protein 4) Storage 5) Removal 6) Detoxification 7) Synthesis
22 Gallbladder Regulation of bile release: Stores and concentrates bile releases bile > cystic duct stimulated by CCK between meals: hepatopancreatic sphincter around duodenal ampulla closes Small Intestine after a meal: CCK is released gall bladder to contract relaxes hepatopancreatic sphincter A. Divisions: Duodenum, Jejunum, Ileum Duodenum Jejunum Ileum B. Membranes 1. Peritoneum parietal visceral retroperitoneal 2. Mesentery 3. Omenta Lesser Omentum Greater Omentum
23 C. Histology 1. Plicae circulares 2. Mucosa Intestinal villi mucosa plicae villi epithelium brush border > (increases surface area 600 times) Each villus contains: a) b) 3. Submucosa 4. Muscular layer 5. Serosa D. Enzymes peptidase E. Hormones CCK sucrase, maltase, lactase lipase breaks down + enterokinase converts to Secretin
24 F. Regulation of Intestinal Secretions G. Absorption in the Small Intestine monosaccharides electrolytes fatty acids and glycerol H. Movements in the S.I. mixing movements peristalsis segmentation overdistended wall triggers peristaltic rush resulting in Large Intestine [cecum, ascending, transverse, descending, sigmoid colon; rectum, anus] A. Cecum ileocecal valve vermiform appendix vestigial part B. Anatomical features haustra diverticula taenia coli epiploic appendages ascending, transverse, descending, sigmoid colon
25 C. Rectum last 15 cm of GI tract rectal columns anus (anal orifice): terminal 23 cm internal anal sphincter external anal sphincter D. Large Intestine Wall Mucosa lack of villi lots of goblet cells intestinal glands Submucosa Muscular Layer Serosa E. Functions of the Large Intestine little or no digestive function absorbs water and electrolytes secretes mucus houses intestinal flora forms feces carries out defecation G. Movements of L.I. H. Feces water, electrolytes, mucus bacteria Color: bile pigments altered by bacteria Odor produced by bacterial compounds
26 Digestion and Absorption A. CHO digestion B. Lipid Digestion C. Protein Digestion D. Water Absorption
27 Life Span Changes Clinical Disorders
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