1. PART 4
The Digestive System

2. Largest gland in the body
The Liver
Largest gland in the body
Performs over 500 functions
Digestive function
Bile production
Performs many metabolic functions
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3. Visceral Surface of the Liver
Figure 22.26
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4. Microscopic Anatomy of the Liver
Hepatocyte – functional cells of the liver
Portal triad composed of
Bile duct tributary
Branch of hepatic portal vein
Branch of hepatic artery
Kupffer cells – destroy bacteria
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5. Microscopic Anatomy of the Liver
Some functions of hepatocytes
Rough ER manufactures blood proteins
Smooth ER produces bile salts, detoxifies poisons
Peroxisomes detoxify poisons (alcohol)
Golgi apparatus packages secretory products
Mitochondria provide energy for liver processes
Glycosomes store sugar
Great capacity for regeneration
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6. Microscopic Anatomy of Liver
Figure 22.27a, c, d
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7. Stores and concentrates bile Expels bile into duodenum
The Gallbladder
Stores and concentrates bile
Expels bile into duodenum
Bile emulsifies fats
Cholecystokinin – released from enteroendocrine cells in response to fatty chyme
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8. The Gallbladder Figure 22.20
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9. The Pancreas Exocrine function Endocrine function
Acinar cells make, store, and secrete pancreatic enzymes
Enzymes are activated in the duodenum
Endocrine function
Produces insulin and glucagon
Regulates blood sugar
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10. The Exocrine Pancreas: Histology
Figure 22.29a, b
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11. Disorders of the Digestive System
Intestinal obstruction
Mechanical obstructions
Adhesions, tumors, or foreign objects
Nonmechanical obstruction
Halt in peristalsis
Trauma
Intestines touched during surgery
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12. Disorders of the Digestive System
Inflammatory bowel disease
Inflammation of intestinal wall
Crohn’s disease
Ulcerative colitis
Viral hepatitis
Jaundice and flu-like symptoms
Major types – A, B, C, and G
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13. Disorders of the Digestive System
Cystic Fibrosis and the Pancreas
Pancreatic ducts become blocked with mucus
Clogged ducts prevent pancreatic juices from entering small intestine
Leads to malabsorption of fats and other nutrients
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14. Embryonic Development of the Digestive System
Alimentary canal formed in week three
Encloses tubular portion of yolk sac
Vitelline duct
Landmark dividing into three regions
Forgut
Midgut
Hindgut
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15. Embryonic Development of the Digestive System
Figure 22.30a, b
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16. The Digestive System in Later Life
Middle age – gallstones and ulcers
Old age – activity of digestive organs decline
Fewer digestive juices and enzymes produced
Absorption is less efficient
Dehydration of fecal mass leads to constipation
Diverticulosis and cancer of digestive organs
Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings