GI Regulation Flashcards
What are the four functions of the GI tract?
Motility
Secretion
Digestion
Absorption
Parasympathetic stimulation has what effect on the gut?
stimulates gut motility
Sympathetic stimulation has what effect on the gut?
inhibits gut motility
Vagus nerve innervates what parts of the GI tract?
Mouth through the transverse colon
Vagus nerve provides parasympathetic innervation
ok
Pelvic nerve supplies parasympathetic innervation to the descending colon.
ok
What are the two layers of longitudinal muscle in the gut?
circular and longitudinal muscle
Which of these two smooth muscle layers is closest to the mucosa (inner lining of the stomach)
Circular
When circular muscle contract, the gut….
shortens
When longitudinal muscles contract, the gut…
lengthens
Vagus nerve in the GI is what percent afferent?
75%
Sympathetic nervous system
innervates muscles/ secretory systems
Vagal- vagal reflex
Both the afferent and efferent responses are vagus nerve controlled
Enteric nervous system…
Primarily made up of the elements of the two plexi (myenteric and submucosal).
Digestive tract is stimulated by both parasympathetic and sympathetic nervous systems
truth
Primary parasympathetic innervation is via what?
Vagus Nerve
Gastrin
17 amino acid peptide with all of its activity in the C-Terminus (four amino acids on the end- Trp, Met, Asp, Phe)
What chemical modifications on gastrin prevent it from being degraded by the amino and carboxy peptides as it moves through the liver?
- Pyroglutamate
- NH2 group
Remember, gastrin is by the GI tract so it goes into the portal circulation which means its going to pass through the liver.
CCK
Cholecystokinin
When a hormone ends in -in, it does what
stimulates
Cholecystokinin does what
stimulates gallbladder, stimulates pancreas, slows gastric motility, relaxes sphincter of oddi
What happens when you de-sulfate the tyrosine residue of CCK
It becomes gastrin pretty much…has gastrin like activity
What is the definition of a physiological dose of a GI hormone
a dose that doesn’t increase blood levels anymore than what you would see in response to a meal.
6 sections of the GI tract according to Johnson’s hormone diagram
- Fundus, Antrum, Duodenum, Jejunum, Ileum, Colon
Gastrin secreted in what segments
Antrum and Duodenum mostly
CCK secreted where?
Duodenum, Jejunum, ileum to an extent
Secretin secreted where?
Duodenum
GIP
Duodenum and Jejunum
know the releasers slide
ok
Gastrin does what
Acid secretion and mucosal growth
CCK does what?
Pancreatic bicarb secretion, pancreatic enzyme secretion, Gallbladder contraction (major), pancreatic growth, ALSO inhibits gastric emptying (amajor)
Secretin does what
Pancreatic bicarb secretion (major)
Bile bicarb secretion
Pancreatic growth
Inhibits acid secretion (probably not significantly in man)
GIP does what?
Insulin release
Motilin does what
Gastric motility and Intestinal motility
What are the three neurocrines?
- VIP (vasoactive intestinal peptide)
- Bombesin
- Enkephaline
VIP does what?
relaxes sphincters, relaxes gut circular muscle, stimulates intestinal secretion, stimulates pancreatic secretion
Bombesin does what?
Also called Gastrin releasing Peptide (GRP)
It is the vagal mediator for gastrin release
Enkephaline does what?
Stimulates smooth muscle contraction and inhibits secretion
Know somatostatin and histamine as the two paracrines
ok
Pt presents with duodenal ulcer, diarrhea, and steatorrhea. What endocrine cell tumor of the GI might tey have?
Gastrinoma (zollinger-ellison syndrome)
What is zollinger ellison syndrome?
Tumor that leads to the over production of gastrin which leads to the over production of acid
Werner Morison Syndrome?
Also called pancreatic cholera
Over production of VIP
Clinically presents as diarrhea, metabolic acidosis, dehydration, hypokalemia,
