physiology 2 -GI secretory products-Locations of GI secretory cells-Gastric parietal cell (not in book) Flashcards
In pernicious anemia, destruction of gastric ____ cells leads to deficiency of ____ required for vitamin B12 uptake in the ____.
Parietal; intrinsic factor; terminal ileum
A patient has chronic abdominal pain and numerous peptic ulcers refractory to proton pump inhibitors. What tumor should be suspected?
Gastrinoma, which is a gastrin-secreting tumor that results in high levels of acid secretion
Describe how pepsin is activated.
It is activated by vagal stimulation of increased acid output, which cleaves inactive pepsinogen to active pepsin
What is the primary role of pepsin? What cells secrete it, and where are these cells found?
Functions in protein digestion; secreted by the gastric chief cells
Bicarbonate is secreted by ____ cells and ____ glands; its function is to ____ acid.
Mucosal; Brunner; neutralize
A patient with a gastrinoma can be expected to also have excessive activation of which pro-enzyme?
Pepsinogen (activated by acid, the release of which is stimulated by gastrin)
Produced by these cells found in this organ, pepsinogen becomes pepsin when there is a high acid content in the stomach.
Chief cells of the stomach
Increased levels of what three molecules cause parietal cells to release gastric acid?
Acetylcholine, histamine, and gastrin
Decreased levels of which hormones will cause parietal cells to secrete gastric acid?
Somatostatin, GIP, prostaglandin, secretin
Where is bicarbonate typically trapped in the GI system?
Bicarbonate is trapped in the mucus that covers the gastric epithelium.
A patient has vitamin B12 deficiency. What part of the GI system could be damaged, impacting vitamin B12 levels?
Parietal cells of the stomach or the terminal ileum (the latter is where vitamin B12 is absorbed as a complex with intrinsic factor)
Where are bicarbonate-secreting mucous glands found? What about bicarbonate-secreting Brunner glands?
Stomach, duodenum, salivary glands, pancreas; duodenum
A patient presents with pallor and macrocytic anemia. She has atrophic gastritis and thus makes antibodies acting at which stomach cells?
Parietal cells (this is pernicious anemia)
HCl and intrinsic factor are released by ____ cells in the ____ of the stomach.
Parietal; body
A patient who received atropine would have ____ (increased/decreased) production of intrinsic factor
Decreased
____ is produced by chief cells in the ____ of the stomach.
Pepsinogen; body
Name three types of secretory cells found in the duodenum and their associated products
I cells (cholecystokinin), K cells (glucose-dependent insulinotropic peptide [GIP], S cells (secretin)
Somatostatin is made by ____ cells in the ____ of the stomach
D, antrum
What influence does atropine have on the gastrointestinal secretory cells?
Blocks vagal stimulation of parietal cells only
Gastrin stimulates the production of which two substances?
Histamine (causes acid secretion) and intrinsic factor
Name four substances that are secreted directly into the lumen of the stomach
Mucus, pepsinogen, intrinsic factor, and HCl
Does gastrin stimulate the basal or apical surface of the parietal cells?
Basal surface (gastrin is secreted into circulation to stimulate enterochromaffin-like and parietal cells)
What cells does gastrin act on to increase acid secretion through histamine release?
Enterochromaffin-like cells
The proton pump of parietal cells can be found on which side of the cell?
The luminal side
