Question

Describe the four steps to skeletal muscle contraction at a molecular level

Answer 1

The four steps to skeletal muscle contraction at a molecular level are: 1) neurotransmitter release and depolarization, 2) calcium release and troponin-tropomyosin complex activation, 3) myosin binding to actin binding sites, and 4) power stroke and muscle contraction.

Step-by-step explanation:

1. The neurotransmitter acetylcholine (ACh) is released at the neuromuscular junction (NMJ) and triggers depolarization in the muscle fiber.
2. An action potential travels along the sarcolemma and triggers the release of calcium from the sarcoplasmic reticulum (SR).
3. Calcium binds to troponin, causing a conformational change in the troponin-tropomyosin complex, which exposes the actin binding sites.
4. Myosin heads of thick filaments bind to actin binding sites, forming cross-bridges. The myosin heads then undergo a power stroke, pulling the thin filaments towards the center of the sarcomere and causing muscle contraction.