GI Regulation Flashcards
4 main GI functions
Motility
Secretion
Digestion
Absorption
2 functions of GI motility
Reduces particle size of material
moves material through gut in an orderly fashion
Parasympathetic GI mediators
Ach
What inhibits release of all GI peptides in the body
Somatostatin
What prevents the liver from decarboxylating Gastrin?
Amide group on the C terminus
What gastrin is released during a meal
G17
What makes CCK different than gastrin
Tyrosine residue at amino 7 is always sulfated (if not CCK acts like gastrin)
Mediators in secretin family
VIP, GIP, Glucagon, Secretin
Where are hormones located in endocrine cells
Basal aspect of the cell
Where is gastrin found
Mostly antrum (fasting gastrin released from duodenum)
5 GI hormones
Gastrin, CCK, Secretin, GIP, motilin
where is CCK found
Duodenum and jejunum
What releases gastrin
Protein break down productions, stomach distention, and nerve activation
What releases CCK
Protein and fat digestion products
What releases secretin
Acid
What releases GIP
Protein, fat, and carb breakdown products
What releases motilin
Nerve stilumation
Gastrin physiological effects
Acid secretion and mucosal growth
CCK effects
Inhibits gastric emptying and causes pancreatic and bicarb secretions
What potentiates secretin secretion
Bicarb released from CCK
Secretin functions
Inhibits acid secretion and stimulates pancreatic bicarb secretion
keeps acid out of the duodenum
GIP functions
Stimulates release of insulin and inhibits acid secretion
When is motilin activated
Only in fasting individuals to stimulate gut activity
3 Neurocrines in GI
VIP, Bombesin (GRP), Enkephalins
VIP functions
Relaxes sphincters and gut circular muscle by stimulating NO
Order of factors released to cause gut relaxation
Ach –> VIP –> NO
Bombesin (GRP) functions
Stimulates gastrin release (from vagus release)
Enkephalins function
Opiods, inhibits intestinal secretion and stimulates SM contraction
2 GI paracrines
Somatostatin and Histamine
Somatostatin functions
Inhibits gastrin release and acid secretion from parietal cells
What releases somatostatin
Acid and Vagus
Where is histamine found in GI
Entercromafin like cells in oxyntic glands
What does histamine release in the GI systems
Gastrin and Ach
Test for Gastrinoma
Secretin, will INCREASE gastrin in gastrinoma
What causes steatorrhea is gastrinomas
Tons of acid inhibits pancreatic enzymes
