Regulators Of GI Function Part II Flashcards
G cells are located in _____ of stomach, along with ____. They are located in the _____ of the _____.
G cells release ____ which can be detected as far down as ____.
Gastrin starts off as propeptie, and major form is the ____ form. The _____ of the sequence has biological activty.
_____ receptor binds with _____.
_____ acts directly on ____ cells via previously mentioned receptor.
_____ acts indirectly via ____-mediated ____ release to stimulate ____ cells.
G cells are located in ANTRUM of stomach, along with DUODENUM. They are located in the BASE of the CRYPTS.
G cells release GASTRIN which can be detected as far down as ILEUM.
Gastrin starts off as propeptie, and major form is the SHORT form. The TERMINUS of the sequence has biological activty.
CCK2 receptor binds with GASTRIN.
GASTRIN acts directly on PARIETAL cells via previously mentioned receptor.
GASTRIN acts indirectly via ECL-mediated HISTAMINE release to stimulate PARIETAL cells.
Vagal activation stimulates multiple responses to regulate acid secretion; it modulates:
- ___ cells which release pepsinogen
- ____ cells which release HCl
- ___ cells which release histamine
- _ cells which release ______
Vagal activation stimulates multiple responses to regulate acid secretion; it modulates:
- CHIEF cells which release pepsinogen
- PARIETAL cells which release HCl
- ECL cells which release histamine
- G cells which release GASTRIN
Gastrin stimulates _____ and ____ proliferation in stomach and _____ (can result in ___ hyperplasia)
Factors that regulate gastrin release:
Meals (mainly ___), ____ gastric pH, ____ stimulation via ____ or ____.
Inhibition:
-______, ____ gastric pH, _____, ___
Gastrin stimulates GASTRIC MOTILITY and MUCOSAL proliferation in stomach and SI (can result in ECL hyperplasia)
Factors that regulate gastrin release:
Meals (mainly PROTEIN), HIGH gastric pH, VAGAL stimulation via G-RP or DISTENION.
Inhibition:
-FASTING, LOW gastric pH, SOMATOSTATIN, CCK
I cells are located in ____ ___ and release ___.
- Main receptor for this is ____
- ____ stimulates ____ contraction and relaxation of _____ of ____.
- also stimulates ______ enzyme secretion via _____.
- Inhibits _____ emptying and _____ secretion.
- main stimulatory factor for ____ release is ____-rich meal.
- ____-RP and ____ enzymes can modulate ___ secretion.
I cells are located in PROXIMAL SI and release CCK.
- Main receptor for this is CCK-1
- CCK stimulates GALLBLADDER contraction and relaxation of SPHINC of ODDI.
- also stimulates PANCREATIC enzyme secretion via VAGUS.
- Inhibits GASTRIC emptying and ACID secretion.
- main stimulatory factor for CCK release is LIPID-rich meal.
- CCK-RP and PANCREATIC enzymes (such as TRYPSIN) can modulate CCK secretion.
S cells are located in ____ ___ and ____.
- S cells are ___-sensors
- Releases _____, which stimulates ______ production in pancreatic ____ cells and _____ glands in _____.
- _____ also acts on cholangiocytes to make bile more ____.
- _____ reduces ___ secretion in stomach, also slows ____ ____< and inhibits _____ secretion.
S cells are located in PROXIMAL SI and BRAIN.
- S cells are pH-sensors
- Releases SECRETIN, which stimulates BICARB production in pancreatic DUCT cells and BRUNNERS glands in DUODENUM.
- SECRETIN also acts on cholangiocytes to make bile more DILUTE.
- SECRETIN reduces ACID secretion in stomach, also slows GASTRIN EMPTYING and inhibits GASTRIN secretion.
Molecular actions of Secretin:
-increases conductance of _____ channel leading to outflow of ____ into the lumen to stimulate ____ secretion.
-_____ regulates secretin secretion.
Molecular actions of Secretin:
-increases conductance of CFTR channel leading to outflow of CHLORIDE into the lumen to stimulate BICARB secretion.
-ACID regulates secretin secretion.
D cells are least abundant enteroendocrine cells. D cells release _____ which is generated from a propeptide.
D cells are closely coupled to _____ cells.
- _____ decreases ____ and ______ secretion, so it directly affects __ and ___ cells.
- _____ also decreases ______ and ___ secretion, and also inhibits _____ contraction.
D cells are least abundant enteroendocrine cells. D cells release SOMATOSTATIN which is generated from a propeptide.
D cells are closely coupled to TARGET cells.
- SOMATOSTATIN decreases ACID and PEPSINOGEN secretion, so it directly affects G and CHIEF cells.
- SOMATOSTATIN also decreases PANCREAS and SI secretion, and also inhibits GALLBLADDER contraction.
Motilin is most important during the _____ period, so it’s released cyclically during _____.
-enhances phase ___ contractions
Motilin is most important during the INTERDIGESTIVE period, so it’s released cyclically during FASTING.
-enhances phase THREE contractions
Ghrelin is produced in ____ and ______. It stimulates ____ contraction and enhances ____ emptying.
It also stimulates ____ and promotes weight gain.
It acts in _____ to trigger hunger. ____-rich meals suppress ghrelin release.
Ghrelin is produced in STOMACH and DUODENUM. It stimulates STOMACH contraction and enhances STOMACH emptying.
It also stimulates APPETITE and promotes weight gain.
It acts in PITUITARY to trigger hunger. CARB-rich meals suppress ghrelin release.
Serotonin-releasing cells in GI tract:
- only enteroendocrine cells found in _____
- AKA enterochromaffin cells
- chemoreceptors via _______
- most of our serotonin is found within these cells
- 5-HT intiates ____ and ______ activity in __ (initiated by mechanical stimulation of ____ ___)
- causes secretion of ______ and _____
- ______ effects on adjacent enterocytes
- causes vaso______
Serotonin-releasing cells in GI tract:
- only enteroendocrine cells found in COLON
- AKA enterochromaffin cells
- chemoreceptors via VILLI
- most of our serotonin is found within these cells
- 5-HT intiates PERISTALTIC and SEGMENTATION activity in SI (initiated by mechanical stimulation of MUCOSAL CELLS)
- causes secretion of CL and BICARB
- PARACRINE effects on adjacent enterocytes
- causes vasoDILATION
