Motility DSA

Question 1

Phasic contractions involve what parts of GI tract

Answer 1

esophagus, antrum, SI

Question 2

tonic contractions include what parts of the GI tract

Answer 2

fundus, LES, ileocecal, internal anal sphincter

Question 3

freq of slow waves in:

• stomach
• duod
• ileum

Answer 3

stomach: 3
duod: 12
ileum: 8-9

Question 4

mechanism of slow wave

Answer 4

Ca2+ in during depolarization and K+ out for repolarization

Question 5

what is a bundle of SM called

Answer 5

syncytium

Question 6

where are the intestinal cells of cajal located

Answer 6

btwn inner circular and outer longitudinal sm layers

Question 7

calcium sodium channels

Answer 7

• allow lots of calcium and small number of sodium ions in

- slow to open and close = long duration of AP

Question 8

slow wave and AP

Answer 8

slow waves allow Na+ but not Ca2+, once reaches threshold Ca2+ rushes in and spike potential occurs which is a contraction

Question 9

SM gut fibers

Answer 9

increase in actin and decrease in myosin little troponin

-intermediate filaments and dense bodies: anchor points for contractility

Question 10

mechanism of contraction gut

Answer 10

1) calcium binds calmodulin which activates protein kinase

2) PK phosphorylates myosin which then acts with actin for a contraction

Question 11

decreased calcium = ___ of myosin by

Answer 11

dephos of myosin by phosphatase

Question 12

calcium sources and which source acts where

Answer 12

ECF: muscle for body of esophagus
SR: LES