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Skeletal Muscle- Excitation

Skeletal Muscle- Excitation. Prof. K. Sivapalan. Muscle Types. Skeletal muscle- attached to skeleton Striated muscle- striations under light microscope. [40 % of the body, other types 10 %]. Smooth muscles- no striations- many subtypes.

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Skeletal Muscle- Excitation

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  1. Skeletal Muscle- Excitation Prof. K. Sivapalan

  2. Muscle Types • Skeletal muscle- attached to skeleton • Striated muscle- striations under light microscope. [40% of the body, other types 10 %]. • Smooth muscles- no striations- many subtypes. • Cardiac muscle- found in heart, striated but different from skeletal muscles Skeletal Muscle Excitation

  3. Muscle Structure • Skeletal muscles connect two structures (bones) through tendons or directly. • Muscle cell is known as muscle fiber, 10-80 µ in diameter, extending from one end to the other end of the muscle. • It is multinucleated, rich in mitochondria, full of myofibrils. • Innervated by one axon at its middle through the motor-end plate. • Sarcolemma is excitable as nerves. [RMP -90] • Sarcoplasmic reticulum forms a tubular system that transmits the action potential into the sarcoplasm. Skeletal Muscle Excitation

  4. Skeletal Muscle Skeletal Muscle Excitation

  5. Myofibrils Skeletal Muscle Excitation

  6. Myofibrils Skeletal Muscle Excitation

  7. Motor End Plate Skeletal Muscle Excitation

  8. Stimulation of the Muscle • Action potential reaches the motor end plate • Calcium entry into axonal terminal • Release of acetyl choline • Ligand gated channels- increase Na+ entry- threshold level • Action potential spreads along the sarcolemma Skeletal Muscle Excitation

  9. Sarcotubular System Skeletal Muscle Excitation

  10. Excitation – Contraction Coupling • Action potentials spread along the Transverse tubular system. • The terminal cisterns release Ca++ • Calcium ions facilitate binding of actin and myosin. • Calcium is transported back into sarcoplamic reticulum and back into terminal cistern. • Removal of calcium results in relaxation Skeletal Muscle Excitation

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