Section 2: Muscle Mechanics Lec 2-1 Flashcards

1
Q

Ft

A

total force

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2
Q

Fc

A

contraction force

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3
Q

Fp

A

passive force

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4
Q

l0

A

length for greatest tension

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5
Q

isometric contraction

A

no shortening of the sarcomere

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6
Q

force is dependent on

A

of crossbridges (muscle, fiber, myofibril)

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7
Q

species differences in sarcomere length at peak tension due to :

A

myosin: length is constant at ~1.6 microm
actin: frog .95 microm
actin: human 1.27 micrometers

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8
Q

true or false: mammals are able to generate force over larger ranges of sarcomere lengths than the frog

A

true

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9
Q

parallel elastic (PE) elements

A

connective tissue surrounding contractile elements

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10
Q

series elastic (SE) elements

A

connective tissue in series with contractile elements (tendon, sarcomeres, titon, nebulin)

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11
Q

summation

A

-increasing force due to increased frequency of stimulation

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12
Q

summation is due to

A

decreased time for deactivation between stimuli

-partly, but not entirely, due to slow Ca++ ATPase

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13
Q

tension=

A

F(muscle/sarcomere length)/ # of crossbridges

**this is true for twitch, submax, and MVC

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14
Q

isotonic contraction

A

constant load, muscle allowed to shorten

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15
Q

slope

A

distance/time or velocity of contraction

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16
Q

latency period

A

the time to lengthen the series elastic elements until tension equals load to be lifted

17
Q

power

A

work/time or FxD/time or force x velocity

18
Q

peak power occurs at _____ of peak force (Po)

19
Q

true or false: a small female subject performing the eccentric exercise could easily fatigue a large man

20
Q

vO2 was significantly less for the eccentric work than for the concentric exercise. what is the equation?

A

VO2 concentric= 5 x VO2 eccentric

21
Q

eccentric contractions

A

lengthening of muscle while it is activated to contract
F external > F muscle
force» peak isometric force

22
Q

what does the force response suggest?

A

muscle is very resistant to lengthening

23
Q

velocity reponse

A

has almost no effect on force

24
Q

Much of daily movement is a combination of _____ and ______ contractions

A

concentric and eccentric contractions

25
concentric contractions F/V due to
F/V due to time to move to the active state and attach myosin heads *** the faster the contraction the fewer the attachments****
26
eccentric contractions F/V due to
number of crossbridges which physically have to be broken
27
at high concentric velocities force is
Force is low and independent of length
28
at low concentric velocities force is
force is strongly determined by length
29
at eccentric velocities force is
force is determined mostly by length very little by velocity
30
factors which affect the isometric tension in a submaximally activated muscle:
- average overlap of actin strands and myosin heads - Free ca++ concentration in cytosol - force/Ca++ (calcium sensitivity)
31
calcium sensitivity defined as
force produced at a given Ca++
32
proposed mechanism for enhanced Ca++ sensitivity
changes in actin-myosin filament spacing
33
Free Ca++ in the cytosol is due to
the number of troponin binding cites occupied
34
optimal length of individual motor units varies within a given muscle suggesting that:
at a given muscle length, different motor units have different mean sarcomere lengths
35
consequences of optimal length of individual motor units varying within a given muscle
- decreases peak force | - extends the length span for available force leading to smooth muscle performance through Greater ROM