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Flashcards in Skeletal Muscle Deck (12)
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1
Q

Excitation-contraction

A
  1. Nerve a.p.
  2. Ach secretion by nerve ending
  3. End-plate potential
  4. Muscle a.p.
  5. Depolarise T-tubules + open Ca2+ channels of R
  6. Increase sarcoplasmic Ca2+
  7. Contraction
  8. Ca2+ pumped into S.R.
  9. Relaxation
2
Q

In contraction:

A
  • Length of actin and myosin doesn’t change
  • H- zone and I-band decrease in length
  • distance between z-discs and M-lines decrease
3
Q

Contractile response pattern

A

Latent, lag, contract, relax

4
Q

Stimulation frequency is dependant on

A

Wave summation + fused tetanus leading to strong contractile response

5
Q

Isometric

A

Muscle length constant but generates force for tension

6
Q

Isotonic

A

Force steady but length of muscle changes

7
Q

Types of isotonic contraction

A
  1. Concentric - muscle tension rises to meet resistance then remains the same as muscle shortens
  2. Eccentric- muscle lengthens due to resistance being greater than force being produced
8
Q

Force depends on

A
  1. no. active motor units
  2. cross-sectional area of muscle
  3. freq. of stimulation
  4. rate at which muscle shortens determined by force velocity conc.
  5. Isometric tension developed depends on muscle length -> declines at longer length
9
Q

Slow muscles are

A

Slow oxidative (light)

10
Q

Fast muscles are

A

a. Fast oxidative (darkest)

b. Fast glycolytic (intermediate)

11
Q

In a force-velocity curve max power =

A

1/3 of max. velocity of shortening

12
Q

Power =

A

Force x velocity of contraction