1 PowerPoint Lecture Outlines to accompany Hole’s Human Anatomy and Physiology Tenth Edition Shier  Butler  Lewis Chapter 17 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

2 Chapter 17 Digestive System Functions of Digestive System ingestion mechanical digestion chemical digestion propulsion absorption defecation

3 Major Organs

4 Alimentary Canal

5 Alimentary Canal Wall

Structure of the Wall Serosa- made of visceral peritoneum, moistens, protects and lubricates Muscular- smooth circular fibers-decreases diameter-smooth longitudinal-shortens tube Sumucosa- nerves, blood vessels, loose c.t., transports absorbed nutrients and nourishes Mucosa- epithelial, some c.t., some muscle secretes mucus, absorb, protect 6

7 Movements of the Tube mixing movements peristalsis

8 Innervation of the Tube submucosal plexus – controls secretions myenteric plexus – controls gastrointestinal motility parasympathetic impulses – increase activities of digestive system sympathetic impulses – inhibit certain digestive actions

9 Mouth ingestion mechanical digestion prepares food for chemical digestion

10 Tongue

11

12 Palate roof of oral cavity

13 Primary Teeth 8 incisors 4 cuspids 8 molars

14 Secondary Teeth

15 Section of a Tooth

16 Salivary Glands

17 Secretions of Salivary Glands Parotid glands clear water, serous fluid rich in amylase Submandibular glands primarily serous fluid some mucus Sublingual glands primarily mucus most viscous

Chemical Digestion in Mouth Saliva L per day Mostly water as a solvent so food can be tasted Mucin-causes food to stick together has lysozyme to kill bacteria Amylase-breaks down starch Neutralizes mouth acids-6.8, cleans mouth 18

19 Pharynx

Connects nasal and oral cavities with larynx and esophagus, lined with mucous mem., muscles constrict Nasopharynx- above soft palate has pharyngeal tonsils on walls, behind nose, passageway for air Oropharynx- below soft palate above epiglottis, palatine tonsils on walls, food/air Laryngopharynx- from epiglottis downward to the esophagus 20

21 Swallowing Mechanism soft palate and uvula raise-nasal air passage shut off hyoid bone and larynx elevate, epiglottis closes off trachea tongue pushes against soft palate longitudinal muscles of pharynx contract pulling pharynx up inferior constrictor muscles relax and esophagus opens peristaltic waves push food through pharynx to the esophagus, to the cardiac sphincter of the stomach

22 Swallowing Mechanism

23 Esophagus

24 Stomach

25 Radiograph of Stomach

26 Lining of Stomach

27 Gastric Secretions pepsinogen from chief cells inactive form of pepsin pepsin from pepsinogen in presence of HCl protein splitting enzyme hydrochloric acid from parietal cells needed to convert pepsinogen to pepsin mucus from goblet cells and mucous glands protective to stomach wall intrinsic factor from parietal cells required for vitamin B 12 absorption

28 Phases of Gastric Secretion Cephalic phase triggered by smell, taste, sight, or thought of food parasympathetic impulses trigger gastric juice secretion-gastrin Gastric phase triggered by presence of food in stomach gastrin released gastric juice secreted Intestinal phase triggered by movement of food into small intestine intestinal cells release intestinal gastrin secretion of gastric juice

29 Regulation of Gastric Secretions

30 Gastric Absorption some water certain salts certain lipid-soluble drugs alcohol

31 Mixing and Emptying Actions

32 Enterogastric Reflex regulates the rate at which chyme leaves the stomach

33 Pancreas

34 Pancreatic Juice pancreatic amylase – splits glycogen into disaccharides pancreatic lipase – breaks down triglycerides trypsin, chymotrypsin, and carboxypeptidase – digest proteins nucleases – digest nucleic acids bicarbonate ions – make pancreatic juice alkaline

35 Regulation of Pancreatic Secretions acidic chyme stimulates release of secretin secretin stimulate release of pancreatic juice

36 Liver

37 Hepatic Lobule

38 The Paths of Blood and Bile in Hepatic Lobule

39 Liver Functions produces glycogen from glucose breaks down glycogen into glucose converts noncarbohydrates to glucose oxidizes fatty acids synthesizes lipoproteins, phospholipids, and cholesterol converts carbohydrates and proteins into fats forms urea synthesizes plasma proteins converts some amino acids to other amino acids stores glycogen, vitamins A,D, B 12, iron, and blood phagocytosis of worn out RBCs and foreign substances removes toxins from blood produces and secretes bile

40 Composition of Bile water bile salts emulsification of fats absorption of fatty acids, cholesterol, and fat-soluble vitamins bile pigments cholesterol electrolytes

41 Gallbladder

42 Regulation of Bile Release fatty chyme entering duodenum stimulate gallbladder to release bile

43 Three Parts of Small Intestine

44 Mesentery suspends portions of the small intestine from the posterior abdominal wall

45 Intestinal Villus

46 Intestinal Epithelium

47 Wall of Small Intestine

48 Secretions of Small Intestine peptidase – breaks down peptides into amino acids sucrase, maltase, lactase – break down disaccharides into monosaccharides lipase – breaks down fats into fatty acids and glycerol enterokinase – converts trypsinogen to trypsin somatostatin – hormone that inhibits acid secretion by stomach cholecystokinin – hormone that inhibits gastric glands, stimulates pancreas to release enzymes in pancreatic juice, stimulates gallbladder to release bile secretin – stimulates pancreas to release bicarbonate ions in pancreatic juice

49 Regulation of Small Intestinal Secretions mucus secretion stimulated by presence of chyme in small intestine distension of intestinal wall activates nerve plexuses in wall of small intestine parasympathetics trigger release of intestinal enzymes

50 Absorption in the Small Intestine monosaccharides and amino acids through facilitated diffusion and active transport absorbed into blood electrolytes and water through diffusion, osmosis, and active transport absorbed into blood

51 Absorption in the Small Intestine fatty acids and glycerol several steps absorbed into lymph and blood

52 Movements of the Small Intestine mixing movements peristalsis – pushing movements segmentation – ringlike contractions overdistended wall triggers peristaltic rush resulting in diarrhea

53 Large Intestine

54 Large Intestinal Wall

55 Functions of Large Intestine little or no digestive function absorbs water and electrolytes secretes mucus houses intestinal flora forms feces carries out defecation

56 Movements of Large Intestine slower and less frequent than those of small intestine mixing movements peristalsis mass movements usually follow meals

57 Feces water electrolytes mucus bacteria bile pigments altered by bacteria provide color smell produced by bacterial compounds

58 Life-Span Changes teeth become sensitive gums recede teeth may loosen or fall out heartburn more frequent constipation more frequent nutrient absorption decreases accessory organs age but the effects are less noticeable

59 Clinical Application Hepatitis inflammation of the liver most commonly caused by viral infection can be caused by reactions to drug, alcoholism or autoimmunity Signs and Symptoms headache low fever fatigue vomiting rash foamy urine pale feces jaundice pain Hepatitis A – not washing hands or eating raw shellfish Hepatitis B – chronic; serum Hepatitis C – serum Hepatitis D – very severe; only produces symptoms if infected with B; serum Hepatitis E, F, G – more rare