Transcript Power Point - Delmar

Chapter 18
Digestive System
© 2009 Delmar, Cengage Learning
Digestive System
• Food must be converted by physical and
chemical changes before it can be used by
the cells; this process is called digestion
• Enzymes
• Alimentary canal
• Accessory organs
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Layers of the Digestive System
• Mucosa
– Innermost lining
• Submucosa
• Circular muscle
• Longitudinal muscle
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Lining of the Digestive System
• Peritoneum
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Parietal
Visceral
Mesentery
Greater omentum
• Peritonitis
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Functions of the Digestive System
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Break down food physically
Change food chemically
Absorb the nutrients
Eliminate the waste products of digestion
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Organs of Digestion
• Mouth (oral or buccal cavity)
• Tongue/accessory organ of digestion
• Salivary glands
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Teeth/Accessory
Organ of Digestion
• Gingivae or gums
• Teeth
– Food chewed or masticated
– Deciduous and permanent teeth
• Structure of the tooth
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Esophagus
• Muscular tube to transport swallowed food
to stomach
• Esophageal wall layers
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Mucosa
Submucosa
Muscular
External serous
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Stomach
• Fundus
– Upper part
• Body or great curvature
– Middle section
• Pylorus
– Lower portion
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Stomach
• Sphincters
– Cardiac sphincter
– Pyloric sphincter
• Four layers of the stomach wall
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Gastric Juices
• Enteroendocrine glands
– Secrete gastrin
• Parietal cells
– Produce HCL and intrinsic factor
• Chief type cells
– Produce pepsinogen
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Gastric Juices
• Mucus cells
– Secrete alkaline mucus
• Rennin
– Found in infants and children
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Small Intestine
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About 20 feet long
Same four layers as the stomach
Duodenum
Jejunum
Ileum
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Digestive Juices in
the Small Intestine
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Enzymes, secretin, and cholecystokinin
Pancreatic juices
Bile
Intestinal juices
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Absorption in the Small Intestine
• Villi
– Makes absorption possible
• Each villi contains a network of blood and
lymph capillaries
• Digested portion passes through the villi into
the bloodstream and lacteals
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Absorption in the Small Intestine
• Undigested portion passes on to the large
intestine
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Accessory Organs of Digestion
• Pancreas
• Liver
• Gallbladder
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Large Intestine
• Also called the colon
• About 5 feet long
• Ileum empties chyme through ileocecal valve
into large intestine
• Secretes mucus to lubricate passageway
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Large Intestine
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Cecum and appendix
Ascending, transverse, and descending colon
Sigmoid colon
Anal canal
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Digestive System Structures
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General Overview of Digestion
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Bolus
Peristalsis
Digestion of protein, fats, and carbohydrates
Absorption of nutrients
Undigested substance - feces
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General Overview of Digestion
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Action in the mouth
Action in the pharynx
Action in the esophagus
Action in the stomach
Action in the small intestine
Action in the large intestine
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Action in the Large Intestine
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Absorption
Bacterial action
Gas formation
Fecal formation
Defecation
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Metabolism
• Within the cells, nutrients are changed into
energy
• Aerobic metabolism
– Oxidation
• Anaerobic metabolism
– Krebs cycle
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Metabolism
• Anabolism and catabolism
• Thyroid hormones
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Animation – Digestion
Click here to play
Digestion animation
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Effects of Aging
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Decrease sensory ability of taste buds
Reduction of saliva
Loss of teeth
Slowing peristalsis
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Disorders – Digestive System
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Stomatitis
Gingivitis
Periodontal disease
Gastroesophageal reflux disease (GERD)
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Disorders – Digestive System
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Hiatal hernia
Heartburn
Pyloric stenosis
Gastritis
Gastroenteritis
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Disorders – Digestive System
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Enteritis
Ulcer
Inflammatory bowel disease (IBD)
Appendicitis
Hepatitis
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Disorders – Digestive System
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Cirrhosis
Cholecystitis
Gallstones
Pancreatitis
Diverticulosis
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Disorders – Digestive System
• Hemorrhoids
• Diarrhea
• Constipation
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