Muscle Contraction Flashcards
excitation
process in which action potentials in motor nerve lead to action potentials in muscle fibers
excitation-contraction coupling
events that link action potentials on sarcolemma to activation of myofilaments
- preparing them to contract
contraction
step where muscle fibers develop tension and shorten
relaxation
when nerve fiber stops stimulating and muscle fiber relaxes and returns to normal length
length tension relationship
tension/force of contraction depends on how stretched/contracted its was
muscle tone
state of partial contraction
muscle twitch
when a muscle is directly stimulated w/ an electrode and exhibits a quick cycle of contraction and relaxation
myogram
graph of a twitch
latent period
delay ~2 msec when muscle is first stimulated and doesn’t immediately respond
internal tension
force generated during latent period, causes no shortening of muscle
external tension
produced once elastic components are taunt to move resisting object and load
- contraction phase
Twitch depends on…
- how stretched muscle was before
- become weaker as muscle fatigues
- vary with temp
- state of hydration
- varies with stimulus frequency
recruitment/multiple motor unit summation
process of brining more motor units into play
size principle
smaller less powerful motor units with smaller/slower nerve fibers are activated first hen larger motor units after
temporal summation
result from two stimuli arriving close together in time
