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Smooth muscle contraction - Coggle Diagram
Smooth muscle contraction
inhibition
SNS
Vasoconstriction
Less blood flow to GI in fight or flight
decreases secretion, motility and blood flow
Hyperpolarization of membrane potential
Norepinephrine, sympathetics
VIP, NO
secreted by ENS
Excitatory
PNS
Vasodilation
Increased blood flow to GI
enhances activity of most GI: increases secretion, motility and blood flow
Substance P
acetylcholine
secreted by ENS
depolarization
stretch, acetylcholine, parasympathetics
Inhibition of inhibitory neurotransmitters allows for peristalsis
Activated: no movement
Inactive movement occurs down GI tract
Peristalsis
Mixing
Tonic smooth muscle
Phasic smooth muscle
layers of smooth muscle
Mucosa
Submucosa
Muscularis externa
serosa/fibrosa
Slow waves
causes NO smooth muscle contraction
aka BER
Controlled by Interstitial cells of Caja
Pacemaker of gut
Slow changes in resting potential
Electrical activity controlled by gap junctions
Spike potential
True action potential that elicit muscle contraction
occurs when slow wave passes over area primed by exposure to NT from ENS
Autonomic Modulation: PNS
M1
Glands
M3
Intestine
Secretion
Stomach
increased motility
sensory nerve fibers
stimulated by irritation
excessive detection of gut
presence of specific chemical substances in gut
salivary glands
esophagus
stomach
gall bladder
pancreas
intestine
colon
recutm
anus
apendix
liver
GI processes
Motility
Secretion
absorption
Circulation
control (neural/hormonal)
20% of CO to intestines during rest
splanchnic circulation
Blood supply in GI
empties into hepatic portal vein
Filtered by liver before taken back to heart
Mesenteric circulation
Blood flow in intestines
Most absorption in small intestine