A&P 1 exam 3 (part 1)
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A&P 1 exam 3 (part 1)
anatomy physiology fall 2014 bio 259
General Principles of Muscle Contraction Fall 2014
single motor neuron and all of the muscle fibers it innervates
the basic and smallest unit of skeletal muscle contraction
if control is important, you want motor units to be
if control is not important, you want motor units to be ?
motor units depend on?
what muscle does
low intervation ratio?
few muscle fibers per motor neuron
high intervation ratio?
more muscle fibers per motor neuron
is control important in low intervation or high intervation ratio?
low intervation ratio
high intervation ratios give you
where are motor units found with low intervation?
extrinsic eye muscles
muscles that move fingers ( like able to pick up a feather and bowling ball)
example of high innervation?
moving large parts of body like the leg, thigh, quads or hamstrings)
in high innervation you do not need?
precise control but minimum amount of power
what does brain control?
motor units and variation between muscles
responsible for contracting motor units
role of nervous system
2 types of muscle contraction
in isotonic contraction, what happens to the muscle fibers?
they shorten, which gives them movement
what happens to muscle fibers in isometric contraction?
muscle fibers do not shorten
moveable force? immoveable force?
generating a force depending on strength and resistance
what happens when there is a combination of isotonic and isometric contractions?
elevating and holding
what is the only thing a muscle fiber can do?
when a muscle receives a nervous impulse what happens?
what can only be initiated with a nervous impulse?
contraction and skeletal muscle
all or none response (invariant)
how does the twitch response length of time vary?
duration varys from muscle to muscle
different muscles have a different length of ?
shortest twitch response?
1/100th of a second
longest twitch response?
1/10th of a second
where is a short twitch response found?
in eye muscles
where is a long twitch respond found?
twitch response happens at what level?
time it takes when neuron arrives at motor unit to when contraction actually occurs
what is a muscle twitch initiated by?
a nervous impulse, stimulus
minimum stimulus strength
is required stimulus is above this, it will generate twitch response
if required stimulus is below this, it will not generate a twitch response
if you see a twitch, then is was atleast ____ and will always get the same response and amount
do muscle fibers twitch at organ level?
contraction of whole muscles and is variable
organ level contraction
the force of organ level contraction depends on?
the number of motor units
min force ?
1--- 1 motor units
max force organ level contraction?
all motor units are contracting
in organ level contraction, the CNS determines?
the number of motor units that will contract
what is variation based on with organ level contraction?
recruitment of motor units
where does recruitment take place?
in the CNS
don't change twitch, but use multiple and overlapping twitches to get the job done
high enough to arrive again before other twitch relaxes
partial twitch fusion where things partially overlap
complete twitch fusion
increase frequency more and stimulus arrive during contraction phase of previous twitch
during what is there no relaxation because the frequency is high enough
this only works for a short period of time
increase duration of contraction by twitch fusion
motor unit stays in ____ until you stop stimulating is or if you run out of energy
twitches get greater and greater
common result of twitch fusion but doesn't always occur
when happens with a higher twitch?
sarcomeres pull 2 times closer together
during summation, when a twitch hits the point where it levels off, the sarcomere is?
only works for seconds?
made up of motor units and prolongs partial contraction
tonus helps to
spread out duration of a single motor unit
what only works for partial contraction
during contraction ATP must be synthesized as fast as?
it is used up
problem with ATP during contractions?
muscle doesn't have enough ATP
transfer PCr to ADP, which then goes to ATP? this happens during?
muscle fiber types?
red fibers rely on?
oxidation of glucose for energy
have a slow twitch, oxidative and darker in color
have a fast twitch, powerful, glycolytic and lighter in color
white fibers contraction?
contract quicker, less time to contract
how is the proportion of red vs white fibers determined?
muscle function and genetics
red vs white fibers use muscle function? when
whether speed and contraction or durability is more important
red vs white fibers use genetics when?
sprinters have high proportion of what type of fibers?
marathon runners have high proportion of what type of fibers?