Lecture Three Flashcards

(52 cards)

1
Q

what is the function of a muscle

A

generate force, allows for movement

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2
Q

what is the function of a motor neuron

A

signal muscle to contract allows for voluntary control

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3
Q

why are muscles and motor neurons important for exercise

A

exercise requires coordinated movements involving multiple muscle groups and varied amounts of force

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4
Q

what are the parts of a muscle

A

muscle- fasicle- fiber- myofibril- sarcomere- thick/thin

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5
Q

what are the structures in a muscle fiber

A

sarcolemma transverse tubules sarcoplasmic reticulum mitochondria nucleus

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6
Q

what is a muscle fiber that is enclosed by a plasma membrane called

A

sarcolemma

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7
Q

what in the muscle stores calcium

A

sarcoplasma reticulum

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8
Q

what is the purpose of calcium in the muscle

A

moves troponin off, allowing tropomyosin to dissociate and expose the actin for binding

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9
Q

what is a thin filament

A

actin

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10
Q

what is a thick filament

A

myosin

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11
Q

facts of sarcomere

A

smallest functional unit of a muscle composed of thick and thin filament

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12
Q

2/3 of all muscle protein is made of

A

myosin

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13
Q

what are thin filament proteins

A

actin troponin tropomyosin

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14
Q

what are the thick filament proteins

A

myosin

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15
Q

what is the function of an alpha motorneuron

A

conduct impulse signals from CNS to muscle and initiate a contraction

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16
Q

where are motorneurons grouped together

A

spinal cord

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17
Q

motor neurons innervates what fibers

A

alpha motorneurons

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18
Q

what composes a motor unit

A

neuron and muscle it innervates

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19
Q

smaller motor unit size is used for

A

dexterity

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20
Q

larger motor unit size is used for

A

force

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21
Q

what is the neuromuscular junction

A

area where nerve “connects” to muscle fiber

22
Q

what signals are used in the neuromuscular junction

A

acetylcholine

23
Q

what maximizes contact for ACh release and capture in neuromuscular junction

A

shape and structure

24
Q

what are the four muscle fiber types

A

Type 1 : slow twitch Type 2a Type 2b Type 2x

25
what happens for muscles with increased length
increased contraction velocity
26
what happens for muscles with increased CSA
increased force
27
if you increase CSA you increase what
force
28
what proteins are in abundance in strong and big muscles
contractile
29
what is muscle architecture
arrangement of muscle fibers relative to the axis of force generation
30
what is an agonist
prime movers, responsible for the movement
31
what is an antagonist
oppose the agonists to prevent overstretching of them
32
what is a synergist
assist the agonists and sometimes fine tune the direction of the movement
33
what is concentric
muscle shortens lowest force generated uses the most energy
34
what is isometric contraction
muscle does not change length
35
what is eccentric contraction
muscle lengthens generates greatest force/ resistive force uses the least amount of energy
36
why does concentric contraction use more energy
takes more energy to overcome force opposing force
37
what is muscle recruitment
the amount of muscle (individual fibers) that are actively contracting at a given point in time
38
recruitment of muscle fibers is controlled by the
nervous system
39
size of the motor unit is generally governed by the
fiber type of the muscle
40
muscle fibers are recruited according to the size of the motor unit
one motor unit at a time
41
what is the size principle of motor unit recruitment
small units to large units used by type one slow units to fast units/ firing freq
42
why are slow motor units recruited first
it requires a smaller neural input to cause a slow motor neuron to reach its threshold and depolarize smaller axon hillock which is easier to depolarize
43
slow motor units recruited first allows two things to happen
recruit slow, fatigue resistant fibers more often allows for a much finer gradation in force production which will enable greater motor control
44
what is a muscle twitch
force produced from a single electrical signal
45
what is contraction freq
number for signals per time period
46
what is summation
progressive increase force with additional signals occurs bc leftover calcium
47
what is tetanus
complete/ "fused" contraction in which force will not increase
48
what is force (tension) directly related to
amount of actin-myosin that are interacting
49
what is optimal length in the length-tension relationship
high tension due to maximal overlap of actin-myosin
50
if velocity increases then force
decreases
51
for velocity to increase, the cross bridge has to
detach faster and faster
52
why cant force increase when velocity increases
fewer cross bridges are engaged at a given moment in time to generate force