Muscle Contraction.

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Presentation transcript:

Muscle Contraction

Motor Unit Motor neuron + all controlled muscle fibers Neuromuscular junctions Connected fiber amounts vs. force produced

Muscle Contraction Step 1: Action potential moves down motor neuron.

Step 2: Acetylcholine (Ach) is released from synaptic vesicles. Step 3: Ach binds to sites on sarcolemma

Muscle contraction Step 4: Action potential moves down T-tubules to sarcoplasmic reticulum.

Stimulation of Skeletal Muscle

Step 5: Ca+ released. Ca+ binds to troponin causing it to change shape Step 5: Ca+ released. Ca+ binds to troponin causing it to change shape. Shape change releases it from tropomyosin (blocker). Step 6: Tropomyosin moves to reveal binding sites on actin (thin filament).

Step 7: Myosin (thick filament) + ATP attaches to actin. Step 8: Myosin heads move actin toward center of A band (power stroke)

Sliding Filament Hypothesis Hyperlink to SFH video: http://youtu.be/mejCXr7p37U

Muscular Contraction Step 9: ATP (energy) or Ca+ is gone, myosin detaches. Step 10: Contraction over Ca is pumped back to the SR Troponin reattaches Tropomyosin reattaches Binding sites covered = RELAXATION

Slow-Twitch vs Fast-Twitch Muscle Fibers Distance runner - aerobic respiration Slow-Twitch vs Fast-Twitch Muscle Fibers Sprinter- anaerobic glycolysis

Isometric and Isotonic Contractions Concentric Eccentric