Transcript PowerPoint to accompany

PowerPoint Lecture Outlines
to accompany
Hole’s Human
Anatomy and Physiology
Tenth Edition
Shier w Butler w Lewis
Chapter
17
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
1
Chapter 17
Digestive System
Functions of Digestive System
• ingestion
• mechanical digestion
• chemical digestion
• propulsion
• absorption
• defecation
2
Major Organs
3
Alimentary Canal Wall
4
Movements of the Tube
• mixing movements
• peristalsis
5
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
6
Palate
• roof of oral cavity
7
Salivary Glands
8
Secretions of Salivary Glands
• Parotid glands
• clear
• water, serous fluid
• rich in amylase
• Sublingual glands
• primarily mucus
• most viscous
• Submandibular glands
• primarily serous
fluid
• some mucus
9
Swallowing Mechanism
• soft palate and uvula raise
• hyoid bone and larynx elevate
• epiglottis closes off top of trachea
• longitudinal muscles of pharynx contract
• inferior constrictor muscles relax and esophagus opens
• peristaltic waves push food through pharynx
10
Swallowing Mechanism
11
Esophagus
12
Stomach
13
Lining of Stomach
14
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 B12
absorption
15
Phases of Gastric Secretion
• Cephalic phase
• triggered by smell, taste, sight, or thought of food
• parasympathetic impulses trigger gastric juice secretion
• 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
16
Regulation of Gastric
Secretions
17
Gastric Absorption
• some water
• certain salts
• certain lipid-soluble drugs
• alcohol
18
Mixing and Emptying Actions
19
Enterogastric Reflex
regulates the rate at which chyme leaves the stomach
20
Pancreas
21
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
22
Regulation of Pancreatic
Secretions
• acidic chyme
stimulates release of
secretin
• secretin stimulate
release of pancreatic
juice
23
Liver
24
Hepatic Lobule
25
The Paths of Blood and Bile in
Hepatic Lobule
26
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
• deaminates amino acids
• forms urea
• synthesizes plasma proteins
• converts some amino acids to other amino acids
• stores glycogen, vitamins A,D, B12, iron, and blood
• phagocytosis of worn out RBCs and foreign substances
• removes toxins from blood
• produces and secretes
27
Composition of Bile
• water
• bile salts
• emulsification of fats
• absorption of fatty acids, cholesterol, and fat-soluble
vitamins
• bile pigments
• cholesterol
• electrolytes
28
Gallbladder
29
Regulation of Bile Release
• fatty chyme entering
duodenum stimulate
gallbladder to release
bile
30
Three Parts of Small Intestine
31
Mesentery
• suspends portions of the
small intestine from the
posterior abdominal wall
32
Intestinal Villus
33
Intestinal Epithelium
34
Wall of Small Intestine
35
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
36
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
37
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
38
Absorption in the
Small Intestine
• fatty acids and glycerol
• several steps
• absorbed into
lymph and blood
39
Movements of the
Small Intestine
• mixing movements
• peristalsis – pushing movements
• segmentation – ringlike contractions
• overdistended wall triggers peristaltic rush
resulting in diarrhea
40
Large Intestine
41
Large Intestinal Wall
42
Functions of Large Intestine
• little or no digestive function
• absorbs water and electrolytes
• secretes mucus
• houses intestinal flora
• forms feces
• carries out defecation
43
Movements of Large Intestine
• slower and less frequent than those of small intestine
• mixing movements
• peristalsis
• mass movements usually follow meals
44
Feces
• water
• electrolytes
• mucus
• bacteria
• bile pigments altered by bacteria provide color
• smell produced by bacterial compounds
45
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
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