Ch. 6 pt 1 Flashcards
T/F: There is only one motor end plate per muscle fiber
True
Tension is progressively elevated until a maximum value for a fiber is reached
summation
prolonged exposure causes fatigue leading to gradual decline in the level of tension produced
tetanus
one of the muscle’s characteristic properties, __, is the ability to respond to a stimulus
irritability
skeletal motor units in mammals that respond to a single stimulus by developing tension in twitch-like fashion are called __ __ cells.
twitch type
rank the types of motor units, placing the ones activates first at the top
1.) type lla, or FOG, fibers
2.) type llb, or FG, fibers
a contraction involving the shortening of a muscle is known as a __ contraction
concentric
during the elbow flexion phase of a forearm curl, which of the following acts as a primary agonist?
the brachialis
parallel elastic component is derived from the __
muscle membranes
series elastic component is derived from the __
tendons
muscle fibers
threadlike cells of a muscle
sarcolemma
membrane surrounding a muscle fiber
sarcoplasm
specialized cytoplasm of a muscle fiber
T/F: antagonists oppose the actions of agonists by developing eccentric tension the same time that agonists are causing movement
true
the fibers of motor units that contract to reach maximum tension quickly after being stimulated
fast twitch type
the fibers of motor units that contract to reach maximum tension gradually after being stimulated
slow twitch type
the fibers are oriented largely in parallel with the longitudinal axis of muscle
parallel fiber arrangement
the fibers lie at an angle to a muscle’s longitudinal axis
pennate fiber arrangement
the formula that defines net torque generated in a joint
T⌄m = F⌄m x d⌄t
a(n) __ contraction describes a contraction involving no change in muscle length
isometric
__ contraction occurs when muscular tension produces a torque larger than the resistive torque at a joint
concentric
a(n) __ contraction occurs when an opposing joint torque exceeds that produced by tension in a muscle
eccentric
muscles that act to stabilize a body part against a particular force assume the role of __
stabilizer(s)
a __ __ refers to a single motor neuron and all muscle fibers it innervates
motor unit
what is true about the tension in a twitch fiber following a stimulus of a single nerve impulse
it rises to a peak value in less than 100 msec and then immediately declines
what represents torque produced by a muscle at a joint
T⌄m
what represents the muscle force
F⌄m
what represents muscle moment arm
d⌄t
those muscles which prevent unwanted accessory actions produced by agonists play the role of __
neutralizers
when rapid, successive impulses activate a fiber already in tension
summation
when a fiber is repetitively activated so that its maximum tension level is maintained for a time
tetanus
internal forces
due to tension in other muscles
external forces
due to the weight of an object being lifted
Which of the following is true of motor units?
There is only one motor end plate per muscle fiber
The net torque generated at a joint is the __
vector sum of the muscle torque and the resistive torque
a muscle that acts to slow or stop the movement of a body segment at a joint plays the role of a(n) __
antagonist
T/F: slow twitch (ST) fibers usually fatigue more quickly than do fast twitch (FT) fibers
false
