Gastric Secretion Physiology

  1. Where are oxyntic glands found and what are the cell types?
    • Body and fundus (proximal 80% of stomach)
    • Parietal and chief cells
  2. Oxyntic glands secrete ____,____, and ___
    • HCl
    • Intrinsic factor
    • Pepsinogen
  3. Parietal cells are located ____ and secrete ____
    • Body of stomach
    • HCl and intrinsic factors
  4. Chief cells are located ____ and secrete____
    • Body of stomach
    • Pepsinogen
  5. G cells are located _____ and secrete_______
    • Antrum of stomach
    • Gastrin
  6. Mucous cells are located ______ and secrete ______
    • Antrum of stomach
    • Mucus pepsinogen
  7. True/false: gastric blood has lower pH than arterial blood when H+ is being secreted
    False; gastric blood has a higher pH when H+ is secreted
  8. What stimulate the secretion of acid from parietal cells?
    • Acetylcholine from PNS
    • Gastrin
    • Histamine
  9. Where does Na+ go in parietal cell? Cl-? H+? K+? HCO3-? H2O?
    • Na+ and HCO3- go out into the interstitial fluid (HCO3- out to protect the stomach cells)
    • While H+ is secreted into the lumen and ultimately K+ as well. Cl- drags water into the Lumen too
  10. HCO3/Cl- exchanger is found on _____ membrane of parietal cell. H+/K+ ATPase is found ____ on parietal cell. K+/Na+ ATPase is found on _____ on parietal cell.
    • Basolateral
    • Apical
    • Basolateral
  11. Which factors inhibit gastric acid secretion?
    • Prostaglandin inhibits ECL cells
    • Somatostatin inhibits ECL and G cells.
  12. Somatostatin is released from which cells?
    D cells in the stomach
  13. True/false: both somatostatin and prostaglandin directly inhibit IP3/Ca2+ and thereby inhibit H+ secretion
    False; they directly inhibit cAMP
  14. Which cellular mechanisms can stimulate H+/K+ ATPase at the apical membrane of parietal cell?
    • IP3/Ca2+
    • cAMP
  15. Which receptors on the parietal cell work through IP3/Ca2+ to stimulate gastric acid secretion?
    • M3 receptor (for Ach from vagus nerve)
    • CCKb receptor (for gastrin)
  16. Which cell secretes histamine? Which receptor does histamine bind to on parietal cell?
    • Enterochromaffin-like (ECL) cells
    • H2 receptor
  17. Which parietal cell receptor stimulate cAMP production en route to secretion of H+?
    H2 (histamine receptor)
  18. H2 is receptor for _____. CCKb is receptor for _____. M3 is receptor for ______
    • Histamine
    • Gastrin
    • Ach
  19. True/false: stimulation of ECL secretion is controlled by gastrin
  20. Which cell secretes gastrin?
    G cell
  21. What is intrinsic factor important for?
    B12 absorption in the ileum
  22. True/false: pernicious anemia develops if intrinsic factor is overly secreted and B12 is not absorbed for RBC maturation in bone marrow
    FALSE; pernicious anemia develops if IF is NOT secreted and B12 is not absorbed
  23. Which cell secretes pepsinogen?
    Chief cells
  24. What activates pepsinogen to become pepsin?
  25. Pepsin is proteolytic in ____ acidity. Inactive when pH is ____
    • High (aka low pH: 1.8-3.5)
    • Above 5
  26. When does pepsinogen secretion occur?
    • Ach release from vagus nerve or enteric nervous plexus
    • Acid in stomach
  27. What secretes mucus and gastrin?
    Pyloric glands
  28. True/false: mucous cells secrete small amount of pepsinogen
  29. Which cell secretes large amounts of viscid mucus?
    Surface mucous cells
  30. What is the pH of surface mucus that covers the stomach surface?
    Alkaline. Protexts from acidity
  31. What can cause damage to protective barrier of gastric mucous?
    Gastric ulcer
  32. What could be causes of peptic ulcer?
    • Overproduction of H+/ pepsin
    • Or loss of protective barrier
  33. True/false: H+ secretion is decreased in gastric ulcers and this leads to an increase in gastrin secretion
    True; H+ secretion decreased because some of it leaks into the mucosa
  34. In duodenal ulcers H+ secretion is _______ than normal. Whereas in gastric ulcers, H+ secretion is ______. Gastrin level in both cases would _____
    • Higher
    • Lower
    • increase
  35. True/false: H pylori can inhibit somatostatin secretion and inhibit HCO3 secretion in the duodenum
    True. This is how H pylori can cause ulcers—gets too acidic
  36. With duodenal ulcers, gastrin secretion _____ in response to food, which would ___ H+ secretion and _____ parietal cell mass
    • Increases
    • Increase
    • increase
  37. What is the name of the syndrome that produces the highest rates of gastrin and H+ secretion?
    Zollinger-Ellison syndrome
  38. What is the cause of Zollinger-Ellison syndrome?
    Gastrinoma- tumor in the pancreas
  39. In Zollinger-Ellison syndrome, pancreatic lipases is inactivated because the pH is _____, and this could could lead to ______.
    • Low (which means high in H+)
    • Steatorrhea
  40. True/false: there is no feedback to decrease gastrin release from the G cells so the H+ levels increase significantly
  41. Which phase of gastric secretion is stimulated via neural signals?
    Cephalic phase
  42. Which phase of gastric secretion is stimulated via food entering stomach creating a vagovagal reflex?
    Gastric phase
  43. What constitutes the intestinal phase of gastric secretion?
    Food in the upper portion of small intestine can cause gastrin release into blood
  44. What can signal the stomach to slow gastric emptying?
    • Distention of small intestine- food in the upper small intestine will trigger the release of Secretin
    • Acid in duodenum
    • Protein breakdown products or irritation of the mucosa
  45. What is Secretin and where is it released from?
    Opposes stomach secretion, released from S cells in the duodenum
Card Set
Gastric Secretion Physiology
GI Midterm- Physiology