ch10pt2 Flashcards
neural stimulation of sarcolemma (skeletal muscle contraction) causes
excitation-contraction coupling
action potential travels along _-___ to __
t-tubules, SR (sarcoplasmic reticulum)
______ is released from SR via ___ ___ ___ _______
calcium, voltage gated ion channels
_______ binds to _____, causing tropomyosin to uncover the ____ ____ on actin
calcium, troponin, active site
interaction between thick and thin filaments causes the muscle to
contract
Contraction of many muscle fibers produces ____ in the muscle
tension
intercellular connection between the nervous system and skeletal muscle fiber
neuromuscular junction (NMJ)
____ ____ (electrical stimulus) is transferred from neuron to the muscle fiber via a _____
action potential, neurotransmitter
Area where calcium ions release onto the sarcolemma
neuromuscular junction
type of motor neuron controlling skeletal muscles
somatic motor neurons
stretches from neuron to muscle
axon
end of each axon branch
synaptic terminal
One axon and all the fibers it stimulates
motor unit
Action potential stimulates ___ __ ____ of the fibers in a motor unit
all or none
Small motor units give _______ control
fine
Large motor units give _________.
strength
neurotransmitter used to pass signal from neuron to muscle fiber
acetylcholine
a narrow space separating the synaptic terminal of the neuron from the opposing motor end plate
synaptic cleft
enzyme which breaks down acetylcholine (ACh). present in synaptic cleft
acetylcholinesterase (AChE)
When the action potential reaches the neuron’s synaptic terminal, it triggers the exocytosis of ___ into the ________ _____.
acetylcholine (ACh), synaptic cleft
ACh diffuses across the
synatpic cleft and binds
to ACh receptors on the
_____ ___ _____. ACh
binding opens ligand-gated
sodium channels. Na+ ions rush into the ___________.
motor end plate, sarcoplasm
Action potential reaches a triad
Releasing Ca2+ , uncovering active sites on Actin, allowing Actin and Myosin interaction
excitation-contraction coupling
Interaction between Actin and Myosin. Shortening of the Sarcomere.
cross bridge cycle
must be present in order to free up active sight on actin
calcium
shortening of sarcomere (cross bridge cycle) requires myosin heads to be in “_______” position
cocked
___ loads myosin heads into ____ position, therefore requiring energy
ATP, cocked
ATP turns to ___ in order to free up energy bond for loading myosin head
ADP + P
myosin head pivoting
power stroke
myosin head lets go of actin
cross-bridge detachment
Duration of neural stimulus, Number of free calcium ions in sarcoplasm, Availability of ATP all affects
contraction duration
Ca2+ concentrations fall, Ca2+ detaches from troponin, active sites are re-covered by tropomyosin.
relaxation phase of skeletal muscle
_______ does not return muscle to original Length, _______ muscle must contract.
relaxation, opposite
A fixed muscular contraction after death. SR breaks down, calcium floods muscle cell, no ATP to bind to myosin and detach cross bridge.
rigor mortis
__ releases ____ when a motor neuron stimulates the muscle fiber
SR, Ca2+
Free ____ in the sarcoplasm triggers ___________
Ca2+, contraction
Contraction is an _____ process requiring ___
active, ATP
Relaxation and return to resting length are ______
passive
