2.1 muscle Flashcards
What is a motor unit?
motor neuron and all of the muscle fibers it innervates
what is a neuromuscular junction?
an interface between neuron and fiber
a muscle fiber is innervated by how many motor units?
ONE, never innervated by more than 1
in a motor unit, all muscle fiber types?
are the same
How can size affect control in a motor unit?
*More fibers per nerve= less control
*less fibers per nerve= fine contorl
(absolute best contorl is 1:1)
What are the 3 types of muscle fibers?
1) Type 1= slow twitch; oxidative (SO)
2) Type 2a= fast twitch; oxidative AND glycolytic (FOG or FO)
3) Type 2b= fast twitch; glycolitic (FG or FX)
Do you produce more force going quickly or slowly? why?
Slowly, use more fiber types
*think of sprint and marathon runners
What is Bowditch’s law?
At threshold for excitement, the intensity of the response is not determined the intensity of the stimulus
What are 5 ways to grade/change muscle tension?
1) temporal
2) spatial summation
3) length of contraction
4) speed of contraction
5) size of muscle
temporal
increase response by increasing the NUMBER or frequency of stmiulus
what is tetanus? What muscle type is this not in?
when a muscle is in constant tension
**can’t have in cardiac muscle because of refractory period
spatial summation
increasedtension as a result of increasing muscle fiber requitment
what is the order of muscle fiber recruitment? Why?
SMALL FIRST b/c it has lowest threshold for recruitment
*type 1, type 2a, type 2b
strength of contraction is dependent and independent of?
the strength of a contraction is INDEPEN of intensity, but DEPENDENT on the frequency of the stimulus
length of fibers associated with? affects what muscles?
associated with joints
*affects all muscles
