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26 Cards in this Set
- Front
- Back
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Actin
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Thin filaments
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Myosin
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Thick filaments
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I Band
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Band of just actin
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A Band
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Band of overlap between actin and myosin
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Z Disc
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Ends of actin attach to this disc
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Sarcomere
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Area of myofibril between two successive Z discs
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Titin (attachments and function)
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One end attaches to Z disc
Other end attaches to myosin Springy fiber that holds things in place |
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NT of nmj
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Acetylcholine (re: muscles)
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Action potential in muscle
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Causes sarcoplasmic reticulum to open, releasing Ca
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Filament that slides in muscle contraction
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Actin (re: muscle contraction)
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Band/disc that changes size in muscle contraction
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Z disc (re: muscle contraction)
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Myosin head
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Has ATPase activity; releases energy for the contraction
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Tropomyosin
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In resting state, block actin's active site
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Troponin
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High affinity for Ca
Responsible for pushing tropomyosin deeper into the actin Allows contraction to occur |
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Myosin head (re: contraction)
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Tilts forward, pulling the actin along
Immediately releases and tilts back Tilts forward again |
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Combination of myosin heads
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Since each works independently, the more heads causes increased force of contraction
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ATP and myosin head
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Before contraction, myosin cleaves ATP forcing the head perpendicular to the actin
ADP remains on the myosin head When myosin attaches to actin, it tilts forward creating force and releasing the ADP |
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Tension-length relationship
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When too long (no overlap of actin and myosin), produce very little tension
When too short (z discs pushing against the myosin), produce very little tension |
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Length for maximum force from whole muscle contraction
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Normal, resting length produces maximum force
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Load-velocity relationship
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With increasing load, the velocity decreases
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Phosphocreatine
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Allows ADP to form back into ATP quickly
Uses its own phosphate bond to generate energy |
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Maximum muscle efficiency
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Contraction at moderate velocity
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Isometric
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Muscle contraction without change in length
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Isotonic
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Muscle change in length, but no change in tension
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Slow muscle fibers (5 properties)
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Type I
Smaller fibers More vasculature More mitochondria More myoglobin |
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Fast muscle fibers (5 properties)
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Type II
Larger fibers Extensive sarcoplasmic reticulum Lots of glycolytic enzymes Less vasculature Fewer mitochondria |
