Final Exam GI Physiology: Glandular Stomach Flashcards
What protects the glandular stomach against microorganisms?
HCl
What protects the glandular stomach against HCl and abrasive ingesta?
Mucin
What is responsible for lubrication of the glandular stomach?
Mucin
The glandular stomach is the initial site of ______ of protein.
hydrolysis
The glandular stomach functions to produce and secrete GIF (gastric intrinsic factor). What is the function of GIF?
It binds to Vitamin B12 and protects it from being digested
What secretes GIF?
The acinar cells of the exocrine pancreas
What is Vitamin B12 essential for?
The maturation of RBCs
What are the types of cells found in the glandular stomach?
Peptic Chief Cells
Parietal Oxyntic Cells
Mucus Neck Cells
What do peptic chief cells do?
Produce enzymes likes pepsinogen, lipase, prorennin, and urease. Little water follows.
What do parietal oxyntic cells do?
Produce HCl and GIF. Water follows.
What do mucus neck cells do?
Produce mucin and HCO3-. Water follows.
HCO3- production is increased by what?
Cholinergic agents and prostaglandins
HCO3- production is decreased by what?
alpha- adrenergic agonists and phospholipase A2 and COX inhibitors
Parietal cells actively transport _____ and ______.
H+ and Cl-
What is alkaline tide?
The alkaline blood leaving the stomach is called alkaline tide.
What are the 3 powerful AGONISTS of parietal cell HCl secretion?
ACh
Histamine
Gastrin
What are some endogenous ANTAGONISTS of parietal cell HCl secretion?
Somatostatin
Prostaglandins
CCK
Secretin
What does ACh act on?
Muscarinic receptors
What does ACh inhibit?
Inhibits secretion of somatostatin
What does ACh promote?
Promotes the secretion of histamine and gastrin
What does Histamine act on?
H2 receptors
Where is Gastrin produced?
From G-cells in the gastric and duodenal mucosa
What does Somatostatin inhibit?
Inhibits release of gastrin
What does CCK do?
Acts to decrease acid by binding to gastrin/CCK receptors with little excitation
Where is secretin produced?
It is an endocrine product of the duodenal mucosal cells
What drugs influence parietal cell activity and therefore production/secretion of HCl?
Atropine H2 Receptor Blockers Inhibitors of H+-K+ ATPase Glucocorticoids COX Inhibitors
What does the administration of glucocorticoids/COX inhibitors do?
Increase acid production/secretion
In general, the cephalic phase and gastric phase of glandular stomach activity are _________.
Stimulatory
In general, the intestinal phase of glandular stomach activity is ________.
Inhibitory
What acts as a feedback inhibitor of acid production in the stomach?
Somatostatin
What inhibits paracrine and endocrine secretions at many sites in the body?
Somatostatin
When you think INHIBITION, you should think __________.
Somatostatin
What does the following?: Increases peptic cell secretion Promotes contraction of LES Promotes contraction of pyloric sphincter Increases gastric motility Is a potent mitogen Is trophic to many cells in the stomach
GASTRIN!
What does the following?:
Is vasodilatory in effect
Increases gastric motility
HISTAMINE
What does the following?:
Inhibits histamine-secreting cells in the stomach
Inhibits CCK-secreting cells and secretin-secreting cells in the small intestine
Slows nutrient absorption in the small intestine
Inhibits exocrine secretion in the pancreas
Inhibits secretion of glucagon by a-cells of the pancreas
Inhibits secretion of insulin by b-cells of the pancreas
SOMATOSTATIN= INHIBITION
What does Ghrelin do?
Stimulates the release of Growth Hormone by the adenohypophysis
T or F: CCK is an anorexigenic substance.
True
T or F: Ghrelin is an orexigenic substance.
True
The relative concentrations of which two substances modulate the gut’s message to the brain as it pertains to food intake?
CCK and Ghrelin
