Transcript chapter_17_powerpoint_l

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
Consists of the alimentary canal and
accessory organs
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Alimentary Canal
About 8 meters long
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Movements of the Tube
• mixing movements
• segmentation
• peristalsis
4
Mouth
• ingestion
• mechanical digestion
(mastication)
• prepares food for
chemical digestion
•Parts
•Cheeks
•Lips
•Tongue
•Palate
•uvula
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Tongue
•Taste
•Moves food
•Forms bolus
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Palate
• roof of oral cavity
•uvula
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Primary Teeth
• 8 incisors
• 4 cuspids
• 8 molars
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Secondary Teeth
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Salivary Glands
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Secretions of Salivary Glands
•Saliva
•Moistens food particles
•Helps bind the food particles together to form bolus
•Begins chemical digestions of carbohydrates (salivary
amylase)
•Helps clean the mouth
•Major salivary glands
• Parotid glands
• Submandibular glands
• Sublingual glands
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Pharynx
Connects nasal and oral
cavities with the larynx
and esophagus
3 parts
• Nasopharynx
• Oropharynx
• Layrngopharynx
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Swallowing Mechanism
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Esophagus
Straight, collapsible tube
about 25 cm long
Carries food from
pharynx to stomach
Lower esophageal
sphincter (cardiac
sphincter) - controls the
opening to the stomach
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Stomach
J-shaped, pouchlike
organ 25-30 cm long
3 regions
• Cardiac region
• Fundic region
• Body
• Pyloric region
Wall contain three
layers of muscle
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Lining of Stomach
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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
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Gastric Absorption
• some water
• certain salts
• certain lipid-soluble drugs
• alcohol
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Mixing and Emptying Actions
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Pancreas
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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
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Regulation of Pancreatic
Secretions
• acidic chyme
stimulates release of
secretin
• secretin stimulate
release of pancreatic
juice
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Liver
Largest internal organ
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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 bile
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Composition of Bile
• water
• bile salts
• emulsification of fats
• absorption of fatty acids, cholesterol, and fatsoluble vitamins
• bile pigments
• cholesterol
• electrolytes
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Gallbladder
Stores bile until it is released into the small intestine
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Regulation of Bile Release
• fatty chyme entering
duodenum stimulate
gallbladder to release
bile
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Three Parts of Small Intestine
Tubular organ 5.5 - 6.0 m long
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Intestinal Villus
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Wall of Small Intestine
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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
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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
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Absorption in the
Small Intestine
• fatty acids and glycerol
• several steps
• absorbed into
lymph and blood
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Movements of the
Small Intestine
• mixing movements
• peristalsis – pushing movements
• segmentation – ringlike contractions
• overdistended wall triggers peristaltic rush
resulting in diarrhea
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Large Intestine
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Functions of Large Intestine
• little or no digestive function
• absorbs water and electrolytes
• secretes mucus
• houses intestinal flora
•Absorbs vitamins K, B12, thiamine and
riboflavin produced by the bacteria
• forms feces
• carries out defecation
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Movements of Large Intestine
• slower and less frequent than those of small
intestine
• mixing movements
• peristalsis
• mass movements usually follow meals
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Feces
• water
• electrolytes
• mucus
• bacteria
• bile pigments altered by bacteria provide color
• smell produced by bacterial compounds
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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
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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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Clinical Application
Ulcers
• Sores in the lining of stomach
• most commonly caused by helicobacter pylorus
• can be caused by reactions to drug and certain foods
Signs and Symptoms
• pain
•Blood in feces
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Clinical Application
Gastric Reflux Disorder
• recurrent heartburn
•Can cause the lining of the esophagus to wear away
•Treat with acid reducers and/or surgery
Signs and Symptoms
• pain
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