Midterm paper

MODULE 10 LO2 Digestive System: Small Intestinal Functions Dr. Lisa Brinn [email protected]

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Mucosal Cells • Enterocytes (absorptive cells)

v Represent 80% of total epithelial cells v Functions:

o Nutrient absorption o Secretion of salts, nutrients, and water

• Goblet cells v Secretes mucus

o Lubricate chyme o Protective barrier

Intestinal Crypts • Enteroendocrine cells

v G cells – secrete gastrin in response to presence of chyme o Stimulates muscle contraction

v I cells – secrete CCK o Pancreas – stimulates secretion of pancreatic juices o Gallbladder - stimulates release of bile o Stomach - controls emptying, suppresses appetite o Small intestine – triggers bowel motility

v K cells – secretes gastric-inhibitory peptide (GIP) in response to chyme entering small intestine o Stimulates insulin secretion

v M cells – secretion of motilin o Accelerates gastric emptying and stimulates intestinal motility o Stimulates production of pepsin

v S cells – secretes secretin in response to acidic chyme o Osmoregulatory function o Inhibitory effect on gastric emptying and motility

• Stem cells – quickly dividing cells • Paneth cells – secrete bacteria killing enzymes

Paneth Cells • Intestinal flora

A. Control population of bad bacteria B. Responsible for manufacturing essential vitamins

Ø Vitamin K o Anti-calcification, anti-cancer, bone-forming o Insulin-sensitizing

Ø B-complex o Thiamine (B1) o Riboflavin (B2) o Pantothenic acid (B5) o Biotin

Ø Folate o + B12 = breaks down folate → create new proteins and forms RBCs

Lamina Propria • Capillaries

v Absorb and carry nutrients → hepatic portal circulation • Lacteals

v Transport large lipids-protein complexes → venous circulation