Physiology Flashcards
2 main types of gut motility
segmentation: isolated, mixing
peristalsis: coordinated contraction for movement
BERs
myogenic, rhythmic waves of depolarization that increase in frequency from 3Hz in the somach to 12Hz in intestines. When coupled with NTs (ACh) this causes peristaltic contractions.
3 stages of swallowing
Voluntary phase of chewing and moving bolus
Pharyngeal phase: soft palate moves up, larynx raises, glottis closes, breathing is inhibited (guiding to esophagus)
Esophageal: UES opens, peristalsis starts
What nerve controls esophageal motility?
Vagal
Hormone that promotes gastric emptying
Gastrin from antral or duodenal G cells
Hormone that inhibits gastric emptying
CCK from duodenum
Function of the MMC?
clears bacterial overgrowth and remaining SI contents during fasting. Occurs on 90 minute cycle.
What hormone mediates MMC?
Motilin
How much secreted fluid is lost per day in feces?
100-200mL of 10L
Which nerve mediates defecation?
Pelvic nerve, a spinal reflex
What molecule mediates mucus production/secretion?
Prostaglandins
4 phases of gastric acid production
Basal: circadian rhythm, highest in PM, lowest in AM
Cephalic: vagal mediated, 30%, ACh release
Gastric: neuro and hormonal, 50-60%, vasovagal reflex
Intestinal: hormonal with gastrin release, 5-10%
Direct pathway of acid secretion
ACh binds M3 to increase Ca
Gastrin binds CCKbR to increase Ca
Histamine binds H2R to increase cAMP
ALL LEAD TO H/K-ATPase phosphorylation
Indirect pathway of acid secretion
ACh and Gastrin act on ECL cells to increase Histamine release