Karius: Physio of Smooth Muscle Flashcards
When skeletal muscle is stretched, what happens to it’s ability to generate tension (force) ?
decreases
When skeletal muscle is stretched, what happens to it’s ability to generate tension (force) ?
WHY?
the cross bridges don’t have enough overlap
Considering skeletal muscle loses the ability to generate force the longer the muscles get, what would happen if the GI track were made of skeletal muscle?
the more it distended because of food, the less it would have the ability to recoil (retract)
muscles of the GUT, vasculature, and respiratory tract must be able to do 5 things
a. contract and maintain contraction for long periods of time, so they have to be energy efficient
b. contract periodically to mix contents of organ
c. maintain shape of organ
d. continue to generate active tension even when stretched
e. use relatively little ATP
in what locations do we find smooth muscle?
vasculature
GI
respiratory tract
urogenital tract
Skeletal muscles are innervated by
alpha motor neurons
smooth muscles are innervated by
intrinsic innervation
(GUT and TRACHEA)
neurons (Sensory and motor)
independent of CNS & PNS
extrinsic innervation
Autonomic nervous system allows CNS to control viscera
NT of Skeletal M.
acetylcholine
norepinephrine or epinephrine
causes contraction of vascular smooth muscle
inhibits gut smooth muscle
nitric oxide (NO)
major inhibitory influence on smooth muscle
acts via cGMP mechanism
from the slides
“one major difference between skeletal and smooth muscle is that smooth muscle can be…”
directly inhibited (caused to relax)
Varicosities
swellings in the axon where NT is released
muscarinic receptors are both
cholinergic and adrenergic (alpha and beta)
NO uses what kind of receptor?
it doesnt, it’s believed to diffuse across the membrane and act on the cGMP system
Skeletal muscle vs smooth m.
innervation
SK : alpha motorneurons
SM: multiple sources, intrinsic, AND, and sensory
