Lecture 16 Muscle 2

Hydrolysis of atp transfers energy to myosin head and

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Unformatted text preview: in head and detaches it from actin. • Hydrolysis of ATP transfers energy to myosin head and reorients it • Contraction continues if ATP is available and calcium level in sarcoplasm is high Transverse (T) Tubule sarcoplasmic reticulum only at I and A bands Sarcoplasmic Reticulum Lateral Sacs Foot Proteins ryanodine receptors Dihydropyridine Receptor Excitation-Contraction Coupling: power stroke Muscle Mechanics – motor unit, motor unit recruitment, and muscle tension Motor Unit The'Motor'Unit • Motor'unit – One'motor'neuron'and'the'muscle' fibers'it'innervates • • Number'of'muscle'fibers'varies' among'different'motor'units Number'of'muscle'fibers'per' motor'unit'and'number'of'motor' units'per'muscle'vary'widely – Muscles'that'produce'precise,'delicate' movements'contain'fewer'fibers'per' motor'unit – Muscles'performing'powerful,'coarsely' controlled'movement'have'larger' number'of'fibers'per'motor'unit Motor Unit Recruitment weak stronger few more and more Motor Unit Recruitment Muscle Tension -...
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