T Nation

Assignment on Skeletal Muscle

I’m doing an assignment and the question is “Describe the process of excitation and contraction of skeletal muscle.”

Are there any articles on here or links that might help me?

Thanks
Changarz

Uni or highschool?

Uni…

  1. Action potential arrives at synaptic terminal of a motor neuron and causes neuron membrane to release the neurotransmiter acetylcholine.

  2. Acetylcholine diffuses across neuromuscular junction and depolarizes the membrane of the muscle fiber, causing an action potential to sweep across the fiber and deep into it via T (transverse) tubules.

  3. This action potential triggers the release of Calcium ions from the sarcoplasmic reticulum into the cytoplasm.

  4. Calcium ions bind to troponin complexes, which causes the tropomyosin to expose the myosin binding sites on the actin fillaments.

  5. Myosin head hydrolizes ATP to ADP and inorganic phosphate, and is in its high-energy configuration.

  6. The high-energy myosin heads bind to actin, forming a cross-bridge.

  7. Releasing the ADP and P, the myosin relaxes to its low-energy state, moving the actin fillaments towards the center of the sarcomere (This is also referred to as the “Power Stroke”).

  8. A new molecule of ATP bonds to the myosin head, breaking the cross-bridge between the actin and myosin and returning the myosin head to its high-energy configuration.

  9. The muscle relaxes when the calcium ions leave the troponin complexes and return to the sarcomere, causing the tropomyosin to re-cover the myosin binding sites on the actin.

:slight_smile:

Thanks for the info