Muscle physiology 3 Flashcards

1
Q

what are the 2 ways to increase strength of a contraction?

A
  1. More motor units (synchronization)
  2. Increase frequency of stimulation to motor unit neuron
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2
Q

_______ motor units recruited first, then _________ recruited

A

Slow-twitch/weak, fas-twitcht/strong

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3
Q

______ twitch is not strong, but resistant to fatigue

A

Slow

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4
Q

______ twitch is strong but fatigue easily

A

Fast

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5
Q

Synchronous activation of motor units increases strength by _____ effect

A

additive

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6
Q

_______ units are usually inhibited but can be activated in rare conditions

A

Largest/Very strong

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7
Q

Nerve bundle is stimulated with _________________, and this recruits more and more motor units

A

increased amount of current

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8
Q

______ means “same load/tension”. the weight on your muscles stays constant and this measures shortening. these type of exercises involve movement where weight isnt changing (squat, bench press, walking, swimming)

A

Isotonic

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9
Q

In isotonic contraction, the ________ helps to stretch elastic properties of skeletal muscle

A

Latent period

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10
Q

does muscle shortening occur during the latency period?

A

YES that’s what builds up tension. This period is due to elastic properties prior to you noticing the weight is moving

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11
Q

does mass change in isotonic movements?

A

NO

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12
Q

Work = (______)( ______)

A

(Force)(distance)

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13
Q

if you move an object you are creating ______

A

work

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14
Q

if you have the same amount of load, but double the amount moved, what happens to work? (EX: moving 10kg 1cm vs 2cm)

A

this doubles the work!
(10x1) vs (10x2)

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15
Q

Same load = _____ tension = _____ force (but work can change dependent on distance)

A

same, same

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16
Q

How can you increase the force needed to lift a heavier load?

A

Recruit more motor units.
If you recruit more → displacement is faster with same weight → more force

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17
Q

Force = number of _________

A

crossbridges in parallel

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18
Q

Force = (______)(_______)

A

mass, acceleration

19
Q

Mass doesn’t change in isotonic system, so if you ______ you produce MORE force

A

accelerate

20
Q

How would recruitment of more motor units affect speed of contraction?

A

it would increase the speed of contraction (increase units/same mass = inc force = inc acceleration)

21
Q

How can marathon runners keep running so long but sprinters are exhausted after a short length?

A

long distance runners use ~⅓ of max force while sprinters use up max force in small amount of time

22
Q

what are the Factors influencing force generation?

A

inertia, force/velocity relationship

23
Q

Object must be accelerated to overcome ________ for it to be moved, and movement continues after contraction because the moving object has _____

24
Q

More inertia to overcome = prolonged ______

A

latency period

25
Relaxation following contraction for a bigger object = relaxation is _____ (slowed down or accelerated?)
accelerated
26
when is there maximum velocity to move an object?
when theres no weight! (you can jump faster/higher holding nothing rather than holding 50lbs)
27
Increasing the load ________ velocity of shortening
decreases
28
Power = (_______)(______)
(force)(velocity)
29
Velocity = (_______)/(________)
(distance)/(time)
30
Faster object is moving = _____ power it has
more
31
maximum power output is at _______ Fmax
1/3 (33%)
32
______ muscle contraction is when muscle length does NOT change. it measures tension/force (tension produced but no displacement). Joints do not move
Isometric
33
______ exercises are static, and contract your muscles without changing their length (think planks, wall-sits, anything that is static and not moving)
isometric
34
do you stretch elastic properties during isometric exercises?
there is NO slack, so you don't need to stretch elastic properties
35
__________ is when you summate mechanical events which increases cross bridges which increases force produced
Wave summation
36
More tension = _____ resistance
more
37
how does latency period for isometric compare to isotonic?
Latency period for isometric is very small compared to isotonic.
38
why is latency period for isometric so much shorter than isotonic?
-You don't need to overcome inertia/build up tension, because elastic component is stretched out prior to the contraction -Object does not move = no inertia to overcome = force buildup is rapid
39
if weight doesn't change but you move faster, you add more _____
force
40
_______ must be stretched by muscle contraction prior to moving the bone
Series elastic
41
______ system is useful to measure summation of contraction
isometric
42
do electrical events have a refractory period? do mechanical events?
-Electrical events in nerve/muscle DO have refractory period -Mechanical events do NOT have refractory period and will continue as long as Ca+ is there
43
_____ occurs when all sarcomeres are contracting at once in recruited motor units
Tetanus
44
Can you tetanize muscle groups at various tensions/weights?
yes! you still experience tetanus when you are holding up a pencil and when you are holding a 50lb weight. You recruit more motor units for heavier object