Cholinergic Nerve

H20 HCO~3 Digestive enzymes

FIGURE 8-15 Biological actions of secretin and CCK on the acinar pancreas, which result in the secretion of H20, HCCV, and digestive enzyme.

disperse the oil droplets. As yet there is no detailed mechanism describing how CCK mediates gallbladder emptying. The CCK-A receptor (see Table 8-5) is present in the gallbladder, and occupancy of this receptor by a CCK antagonist specifically blocks gallbladder emptying.

3. Intestinal Secretion

Several gut hormones, including VIP, GIP, secretin, CCK, and glucagon, and prostaglandins Ej, E2, and ¥2a have been shown to affect the small intestine and colon by either inhibiting the active absorption of electrolytes and H20 or stimulating the secretion of H20 and electrolytes. Both VIP and the prostaglandins are potent stimulators of the adenylate cyclase-cAMP system,

TABLE 8-11 Major Organic Components of Human Bile-

Component

Concentration (mg/ml bile)

Dihydroxycholanic acids Cholic acid

Phospholipid (mostly lecithin)

Protein

Cholesterol

Bilirubin

Hexose and hexosamine

0 0

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