Muscle III (WS 17)

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created 3 years ago by sh7606
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1

Tension Development in Muscle

1. Fiber length (before contraction)
2. Previous contractions and rate of stimulation
3. Extent of fatigue (depletion of resources)
4. Thickness of fibers

2

Energy Sources for Contraction

1. ATP- a primary source (allows for a few seconds of contraction)
2. Phosphocreatine- Immediate backup, replenishes ATP
3. Muscle Glycogen (in muscle) and blood glucose (in blood)
4. Muscle and Blood fatty acids- reserves

3

ATP and Phosphocreatine

ATP: Aerobic respiration Oxygen, Glucose or fatty acids, generates up to 36 ATP's per glucose

Phosphocreatine: Anaerobic respiration, fast contraction, no O2 needed, yields only 2 ATP per glucose

4

Muscle Fatigue

The muscle is unable to generate power or create tension
Sustained contraction of muscle over long time causes fatigue

Caused by a number of mechanisms

1. Central Factors: "feeling, perception" by CNS due to lactic acid- not true. muscle exhaustion
2. Peripheral: Depletion of ACH, ATP, and Glycogen stores
Accumulation of H+ or Pi levels, lactate, and high ECF K+

5

Tetanus

Two Types:
1. Unfused Tetanus- incomplete, bumps are closer together
Fiber partially relaxes

2. Complete/Fused Tetanus- due to a build up of calcium, is one big bump
A lot of inhibition and troponin, because when you contract so much, you rid of some of the elastic elements of the muscle
No relaxation, maximum tension

6

Fiber Thickness

Varies depending on 1) location and 2) extent of training

the number of fibers we have is fixed early in life, and is regulated by myostatin and cytokine