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27 terms

SGU Physiology - Muscles

STUDY
PLAY
fasiculus
made up of mm fibers
fiber
made up of myofibrils
actinin
prot in Z line, connects Actin to Z line
titin
connects Z line to M line
thin filament
2 globular actin chains wound in to a double helix
tropomyosin
sits betw 2 chains actin chains, length of 7 ctins
troponin I
bins to actIn, holds it in place
troponin T
binds to Tropomyosin
troponin C
binds to Ca2+
power stroke
the act of moving myosin and actin toward the M line to shorten the sarcomere
Ryanodine SR Ca2+ channels
open in response to volt-dep Ca2+ channels to further inc intracellular Ca2+
twitch
single stimulus of mm
active force
Max F gen by isometric twitch
preload
amt of F in mm before contraction
afterload
initial F developed by mm before shortening (F gen to lift load)
Vmax
measure of myosin ATPase activity (crossbridge rate)
recruitment
spatial summation, increases proportion of mm fibers stimulated
tetanux
max freq to get sustained contraction
unfused tetanus
tetanus with slight flux in F betw stimuli
fused tetanus
tetanus with no flux in F betw stimuli
motor unit
all the mm fibers innervated by the bundles of 1 motor neuron + the motorneuron itself
slow (oxidative)
type of motor units that are recruited first
temporal summation
increased frequency of stimuli
spatial summation
increased recruitment of motor units
dense bodies
connect myofibrils to cells in smooth mm
unitary smooth mm
smooth mm that has gap junctions, found in GI, uterus, bladder
multiunit smooth mm
under neural control => fine control, found in iris, bl vessels