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25 Cards in this Set
- Front
- Back
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Components of the Neuromuscular System
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- Muscle Structure
- Sliding Filament Theory - Muscle Activation - Neural Factors |
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Muscle MACrostructure
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- Epimysium
- Endomysium - Perimysium - Sarcolemma (= cell membrane) - Sarcoplasm (= cell cytoplasm) |
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Muscle MICrostructure
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- Myofibril (= composed of sarcomeres)
- Sarcomere (= smallest functional unit of muscular system) - Tropomyosin |
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What is tropomyosin?
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Covers the active sites on actin when contraction is occurring.
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Length-Tension Relationship
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(y-axis = tension; x-axis = length of muscle)
- Total tension = combination of active tension & stretching - Force generation increases when muscle is slightly stretched |
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Resting Phase
(Muscle Activation) |
Ca+ stored in sarcoplasmic reticulum
Few myosin x-bridges attached to actin |
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Excitation Phase
(Excitation-Contraction -> Muscle Activation) |
- AP travels down to axon terminal, stimulates release of ACh
- Depolarization of sarcolemma & t-tubules - Receptors in SR activate & release Ca+ - Ca+ binds to troponin & shifts tropomyosin - Active sites on actin are now exposed |
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Contraction Phase
(Excitation-Contraction -> Muscle Activation) |
- Cock & bind (myosin head cocks back & binds to active site on actin)
- Pull ("power stroke") myosin is pulling on actin filament towards the sarcomere |
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Recharge Phase
(Muscle Activation) |
- Repeat of x-bridge cycling
- cock-bind-pull-release - Requires Ca+, 2 ATP, myosin ATPase |
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Relaxation Phase
(Muscle Activation) |
- Neuron does not release ACh (leads to no more depolarization & Ca+ is actively pumped in SR)
- Active sites on actin are recovered - Muscle fibers return to normal length |
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Does lactate cause fatigue?
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No
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Lactate increases..
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- H+
- Pi - NH4+ |
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What is the rate limiting enzyme in anaerobic glycolysis?
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Phosphofructokinase (PFX)
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What does the "phosphagen system" do?
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provides ATP for short term, high intensity activities
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What is "glycolysis"?
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the breakdown of sugars (CHOs) to resynthesize ATP
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List the 3 biological energy systems:
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1. Phosphagen
2. Glycolysis (fast/aerobic, slow/anaerobic) 3. Oxidative ("aerobic") |
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The electron transport chain is part of which energy system?
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the Oxidative System
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What are the primary substrates for the Oxidative System?
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- CHOs
- Fats |
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What is the cutoff (in seconds) for use of the phosphagen energy system?
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15 seconds
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What is the duration (in seconds) for use of the glycolysis system?
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30 seconds to 2 minutes
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What is the duration (in minutes) for use of the oxidative system?
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Past 2 minutes
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Phosphagen Depletion:
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- 5-30s of high-intensity exercise
- CrP decreases ~50-70% |
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ATP regeneration - half-life:
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20 seconds - about 50%
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ATP regeneration (in %) @ 40 seconds
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75% repleted
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ATP regeneration (in %) @ 1 minutes
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87.5% repleted
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