GI 2 Flashcards
zymogen
inactive form of digestive enzymes
mucins
viscous glycoprotein secretions that protect GI cells and lubricate the contents
goblet cells
aka mucus cells, but in the intestines and not in stomach or salivary glands
Two purposes of motility:
- moves food from mouth to anus
- mechanically mixing food breaks into smaller particles
Motility is determined and modified by:
properties of smooth muscles and chemical input from nerves, hormones, and paracrine signals
Increased _____________ is the signal for smooth muscle contraction
cytosolic calcium
slow waves
spontaneous depolarizations in GI smooth muscle
phasic smooth muscle
cycles between contraction and relaxation (ex. intestine)
tonic smooth muscle
is usually contracted (ex. a sphincter that relaxes to allow material to pass)
Slow waves likely originate from…
interstitial cells of canal (ICC)
interstitial cells of canal (ICC)
a network of modified smooth muscle cells serving as the pacemaker for slow wave activity
What are the 3 basic patterns of contraction?
migrating motor complex, peristaltic contractions, segmental contractions
migrating motor complex (motilin)
sweeps food remnants and bacteria out of the upper GI tract and into the large intestine (between meals)
peristaltic contractions
responsible for forward movement; contraction of circular muscle behind a mass of food
bolus
a mass of food
segmental contraction
responsible for mixing; small segments alternatively contract and relax (no net forward movement)
_____ and ________ are the primary regulated functions in the GI system.
motility and secretion
ENS is formed by…
submucosal and myenteric plexus
Short reflexes are integrated entirely within the..
ENS
Long reflexes are integrated within..
the CNS
Myenteric plexus is responsible for..
motility
Submucosal plexus is responsible for..
secretion from GI secretory cells
cephalic reflex
If a long reflex begins in the brain
ENS receives info from the VNS via…
autonomic neurons
