Flashcards in Wk1 GI Phys Overview Deck (44):
4 major layers of GI wall?
3. Muscularis Externa
Three sub-layers of the GI mucosa:
2. Lamina propria
3. Muscularis mucosae
Primary component of the GI sub-mucoa:
submucus nerve plexus
Three sub-layers of the GI muscularis externa:
1. Circular muscle
2. Myenteric nerve plexus
3. Longitudinal muscle
Main difference between small intestine and colonic mucosa?
Small intestine has villi (increased surface area)
Colon is flat to lumen
Why such high rate of turnover in GI epithelial cells?
prevents accumulation of mutations due to toxin exposure
Organs with two layers of mucus:
Organ with one layer of mucus:
What protects protein core of mucus from proteases?
**carbohydrate side chains attract water to form gel
Exocrine digestive enzymes are secreted via?
Zymogen docking and dumping stimulated by increase in which two substances?
Small bowel overgrowth of bacteria causes increase in organic acid production and pulls water into lumen from the blood stream leading to:
Infection causing an excess secretion of chloride drawing water into the lumen causes?
antidiarrheal that slow transit time leading to increased fluid absorption:
Average transit time of the esophagus:
Average transit time of the stomach:
Average transit time of the small intestine:
Average transit time of the colon:
Biochemical characteristic of smooth muscle sphincters:
maintain tone without increase in intracellular Ca2+
Slow wave electrical activity of SM cells initiated by?
interstitial cells of Cajal
Increased AP generation of SM cells caused by increased?
Review SM contraction on slide...
NT released by enterochromaffin cells?
role of serotonin in the gut?
afferent gut sensation
Excitatory NT's of the enteric nervous system:
Inhibitory NT's of the enteric nervous system:q
vasoactive intestinal peptide
45 and 46
NT's that generally decrease GI SM contractility:
(Sympathetics....fight or flight)
NT's that generally increase GI SM contractility:
(parasympathetics....rest and digest)
Primary excitatory NT from sensory cells and motoneurons to muscle, epithelium, secretory cells and interneuronal junctions; increases intracellular Ca2+:
released from vagal nerve endings to stimulate G cell secretion of gastrin:
Gastrin releasing peptide
an excitatory transmitter generally co-released with acetylcholine:
relaxes smooth muscle in esophagus and stomach
stimulates fluid secretion and promotes dilation of GI vasculature
Vasoactive Intestinal Peptide (VIP)
an inhibitory transmitter co-release with VIP from inhibitory motoneurons
transmitter review table on slide...
G cells in antrum of stomach detect amino acids leading to pepsinogen and H+ release by parietal cells:
I cells in duodenum/jejunum detect fat and amino acids, secretion of pancreatic enzymes and bile salts involved in fat uptake:
S cell primarily in duodenum/jejunum detect acid stimulates secretion of pancreatic juice including BICARB and inhibits gastric motility:
K cells in D/J detect carbs and fat to inhibit gastric acid and stimulate insulin release from pancreas:
gastric inhibitory peptide or glucose dependent insulinotropic peptide
secreted by endocrine cells; released cyclically during fasting state to initiate Migrating Motor Complex
Paracrine regulator from ECL cells:
Paracrine regulator from D cells:
Vocab word: burping?