Where are oxyntic glands found and what are the cell types?
Body and fundus (proximal 80% of stomach)
Parietal and chief cells
Oxyntic glands secrete ____,____, and ___
HCl
Intrinsic factor
Pepsinogen
Parietal cells are located ____ and secrete ____
Body of stomach
HCl and intrinsic factors
Chief cells are located ____ and secrete____
Body of stomach
Pepsinogen
G cells are located _____ and secrete_______
Antrum of stomach
Gastrin
Mucous cells are located ______ and secrete ______
Antrum of stomach
Mucus pepsinogen
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
What stimulate the secretion of acid from parietal cells?
Acetylcholine from PNS
Gastrin
Histamine
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
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
Which factors inhibit gastric acid secretion?
Prostaglandin inhibits ECL cells
Somatostatin inhibits ECL and G cells.
Somatostatin is released from which cells?
D cells in the stomach
True/false: both somatostatin and prostaglandin directly inhibit IP3/Ca2+ and thereby inhibit H+ secretion
False; they directly inhibit cAMP
Which cellular mechanisms can stimulate H+/K+ ATPase at the apical membrane of parietal cell?
IP3/Ca2+
cAMP
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)
Which cell secretes histamine? Which receptor does histamine bind to on parietal cell?
Enterochromaffin-like (ECL) cells
H2 receptor
Which parietal cell receptor stimulate cAMP production en route to secretion of H+?
H2 (histamine receptor)
H2 is receptor for _____. CCKb is receptor for _____. M3 is receptor for ______
Histamine
Gastrin
Ach
True/false: stimulation of ECL secretion is controlled by gastrin
True
Which cell secretes gastrin?
G cell
What is intrinsic factor important for?
B12 absorption in the ileum
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
Which cell secretes pepsinogen?
Chief cells
What activates pepsinogen to become pepsin?
HCl
Pepsin is proteolytic in ____ acidity. Inactive when pH is ____
High (aka low pH: 1.8-3.5)
Above 5
When does pepsinogen secretion occur?
Ach release from vagus nerve or enteric nervous plexus
Acid in stomach
What secretes mucus and gastrin?
Pyloric glands
True/false: mucous cells secrete small amount of pepsinogen
True
Which cell secretes large amounts of viscid mucus?
Surface mucous cells
What is the pH of surface mucus that covers the stomach surface?
Alkaline. Protexts from acidity
What can cause damage to protective barrier of gastric mucous?
Gastric ulcer
What could be causes of peptic ulcer?
Overproduction of H+/ pepsin
Or loss of protective barrier
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
In duodenal ulcers H+ secretion is _______ than normal. Whereas in gastric ulcers, H+ secretion is ______. Gastrin level in both cases would _____
Higher
Lower
increase
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
With duodenal ulcers, gastrin secretion _____ in response to food, which would ___ H+ secretion and _____ parietal cell mass
Increases
Increase
increase
What is the name of the syndrome that produces the highest rates of gastrin and H+ secretion?
Zollinger-Ellison syndrome
What is the cause of Zollinger-Ellison syndrome?
Gastrinoma- tumor in the pancreas
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
True/false: there is no feedback to decrease gastrin release from the G cells so the H+ levels increase significantly
True
Which phase of gastric secretion is stimulated via neural signals?
Cephalic phase
Which phase of gastric secretion is stimulated via food entering stomach creating a vagovagal reflex?
Gastric phase
What constitutes the intestinal phase of gastric secretion?
Food in the upper portion of small intestine can cause gastrin release into blood
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
What is Secretin and where is it released from?
Opposes stomach secretion, released from S cells in the duodenum
