GI - Physiology (GI Regulatory substances) Flashcards
Pg. 345 in First Aid 2014 Sections include: -GI regulatory substances
What cells are the source of cholecystokinin? Where in the GI system are these cells found?
I cells (duodenum, jejunum)
What cells are the source of gastrin? Where in the GI system are these cells found?
G cells (antrum of stomach)
What cells are the source of glucose-dependent insulinotropic peptide? Where in the GI system are these cells found?
K cells (duodenum, jejunum)
Where in the GI system is Motilin found?
Small intestine
What cells are the source of secretin? Where in the GI system are these cells found?
S cells (duodenum)
What cells are the source of somatostatin? Where in the GI system are these cells found?
D cells (pancreatic islets, GI mucosa)
In what general structure(s) is Vasoactive intestinal polypeptide (VIP) found? Give 3 areas in the body in which it is found in this (these) structure(s).
Parasympathetic ganglia in sphincters, gallbladder, and small intestine
What are the 4 actions of cholecystokinin (CCK)?
(1) Increase pancreatic secretion (2) Increase gallbladder contraction (3) Decrease gastric emptying (4) Increase sphincter of Oddi relaxation
What 2 factors regulate cholecystokinin, and how?
Increased by fatty acids, amino acids
What does CCK act on to cause pancreatic secretion?
CCK acts on neural muscarinic pathways to cause pancreatic secretion
What are the 3 actions of gastrin?
(1) Increase gastric H+ secretion (2) Increase growth of gastric mucosa (3) Increase gastric motility
What regulation factors increase versus decrease gastrin? Note: There are 4 factors for increasing gastrin.
INCREASE: by stomach distention/alkalinization, amino acids, peptides, vagal stimulation; DECREASE: by stomach pH < 1.5
In what syndrome is gastrin markedly elevated?
Markedly elevated in Zolinger-Ellison syndrome
Chronic use of what medication increases gastrin? What other 2 substances are potent stimulators of gastrin?
Increased by chronic PPI use; Phenylalanine and Tryptophan are potent stimulators
What are the 2 categories of action by glucose-dependent insulinotropic peptide? What occurs in each category?
EXOCRINE: decrease gastrin H+ secretion; ENDOCRINE: increase insulin release
What 3 factors regulate glucose-dependent insulinotropic peptide, and how?
Increased by fatty acids, amino acids, oral glucose
What is another name for glucose-dependent insulinotropic peptide?
Also known as gastric inhibitory peptide (GIP)
Compare the use of oral versus IV glucose in response to GIP secretion.
An oral glucose load is used more rapidly than the equivalent given by IV due to GIP secretion
What is the action of motilin?
Produces migrating motor complexes (MMCs)
What is the regulation of motilin?
Increased in fasting state
Give an example of a motilin receptor agonists. How are such drugs used?
Motilin receptor agonists (e.g., erythromycin) are used to stimulate intestinal paralysis
What are the 3 actions of secretin?
(1) Increase pancreatic HCO3- secretion (2) Decrease gastric acid secretion (3) Increase bile secretion
What factors regulate secretin, and how?
Increased by acid, fatty acids in lumen of duodenum
What effect does increased HCO3- due to secretin have, and what does this allow?
Increased HCO3- neutralizes gastric acid in duodenum, allowing pancreatic enzymes to function