Digestive System

  1. mucous neck cells
    produce a sticky alkaline substance that coats the stomach mucosa
  2. parietal cells
    • secrete HCl and intrinsic factor
    • HCl makes stomach acidic, which is necessary for activation of pepsinogen
    • acidity also helps in food digestion by denaturing proteins
  3. chief cells
    produce pepsinogen
  4. enteroendocrine cells
    releases histamine, serotonin, somatostatin, and gastrin
  5. rennin
    • produced in infants
    • breaks down the milk protein (casein)
  6. hormone ghrelin
    • produced by the stomach
    • stimulates hunger
  7. cholecystokinin (CCK)
    • produced in duodenum
    • stimulus: fatty chyme
    • targets pancreas & gallbladder to increase output of pancreatic juice and bile
  8. Gastric inhibitory peptide (GIP)
    • produced in duodenum
    • stimulus: glucose, fatty acids, amino acids
    • targets stomach (inhibits HCl release) and pancreas (stimulates insulin release)
  9. gastrin
    • produced in stomach G cells
    • stimulus: food in stomach
    • targets stomach (increase HCl secretion) and causes relaxation of ileocecal valve
  10. histamine
    • produced in stomach mucosa
    • stimulus: food in stomach
    • targets stomach and makes parietal cells release HCl
  11. secretin
    • produced in duodenum
    • stimulus: acidic chyme
    • inhibits gastric gland secretion and increases output of pancreatic juice
  12. serotonin
    • produced in stomach 
    • stimulus: food in stomach
    • causes contraction of stomach muscle
  13. somatostatin
    • produced in stomach and duodenum
    • stimulus: food in stomach
    • inhibits gastric secretion, GI blood flow (inhibiting intestinal absorption) and bile release
  14. vasoactive intestinal peptide (VIP)
    • produced in enteric neurons
    • stimulus: chyme containing partially digested food
    • induces smooth muscle relaxation in the stomach and inhibits acid secretion
Card Set
Digestive System