1. PART 3
The Digestive System

2. Digested residue contains few nutrients
The Large Intestine
Digested residue contains few nutrients
Small amount of digestion by bacteria
Main functions
Absorb water and electrolytes
Mass peristaltic movements force feces toward the rectum
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3. Gross Anatomy of Large Intestine
Subdivided into
Cecum, vermiform appendix, colon, rectum, anal canal
Special features of large intestine
Teniae coli
Thickening of longitudinal muscularis
Haustra
Puckering created by teniae coli
Epiploic appendages
Fat-filled pouches of visceral peritoneum
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4. Gross Anatomy of Large Intestine
Cecum
Blind pouch
Beginning of large intestine
Vermiform appendix
Contains lymphoid tissue
Neutralizes pathogens
Colon
Divided into distinct segments
Ascending, transverse, descending, and sigmoid colon
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5. Gross Anatomy of Large Intestine
Rectum
Descends along the inferior half of the sacrum
Anal Canal
The last subdivision of the large intestine
Lined with stratified squamous epithelium
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6. Gross Anatomy of Large Intestine
Figure 22.22a
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7. Gross Anatomy of Large Intestine
Figure 22.22b
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8. Vessels and Nerves of the Large Intestine
First half of large intestine
Arterial supply - superior mesenteric artery
Innervation
Sympathetic innervation – superior mesenteric and celiac ganglia
Parasympathetic innervation – vagus nerve
Copyright © 2008 Pearson Education, Inc., publishing as Benjamin Cummings

9. Vessels and Nerves of the Large Intestine
Distal half of large intestine
Arterial supply - inferior mesenteric artery
Innervation
Sympathetic innervation – inferior mesenteric and hypogastric plexuses
Parasympathetic innervation – pelvic splanchnic nerves
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10. Defecation Reflex Figure 22.23
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11. Microscopic Anatomy of Large Intestine
Villi are absent
Contains numerous goblet cells
Intestinal crypts – simple tubular glands
Lined with simple columnar epithelial tissue
Epithelium changes at anal canal
Becomes stratified squamous epithelium
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12. Mucosa of the Large Intestine
Figure 22.24
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