Vrushali Khadse
Dec 2, 2023
Mechanism of contraction of muscle?
1 view
1 view
1 answer
Sort By
ChatGPT
Dec 2, 2023
The mechanism of muscle contraction involves a complex series of events that occur at the molecular level. Here is a simplified explanation of the process:
1. Nerve impulse: A nerve impulse, or action potential, is generated by the nervous system and travels down a motor neuron to reach the muscle fiber.
2. Calcium release: The action potential triggers the release of calcium ions from the sarcoplasmic reticulum, a specialized network of membranes within the muscle fiber. Calcium ions bind to a protein called troponin, which is part of the thin filaments within the muscle fiber.
3. Cross-bridge formation: The binding of calcium to troponin causes a conformational change in the thin filaments, exposing binding sites for myosin, a thick filament protein. Myosin heads bind to these sites, forming cross-bridges between the thick and thin filaments.
4. Power stroke: When ATP (adenosine triphosphate) is hydrolyzed, the myosin heads undergo a conformational change, pulling the thin filaments towards the center of the sarcomere (the basic unit of muscle contraction). This is known as the power stroke.
5. Sliding filament theory: The power strokes of multiple myosin heads cause the thin filaments to slide past the thick filaments, resulting in the shortening of the sarcomere. This process occurs simultaneously in all sarcomeres within a muscle fiber, leading to muscle contraction.
6. ATP reattachment: After the power stroke, the myosin heads release the ADP (adenosine diphosphate) and phosphate molecules. ATP then binds to the myosin heads, causing them to detach from the thin filaments.
7. Relaxation: The calcium ions are actively pumped back into the sarcoplasmic reticulum, which causes the troponin to return to its original conformation. This blocks the myosin binding sites on the thin filaments, preventing further cross-bridge formation and allowing the muscle to relax.
It is important to note that this is a simplified explanation of the mechanism of muscle contraction, and there are many more intricate details and regulatory proteins involved in the process.
1. Nerve impulse: A nerve impulse, or action potential, is generated by the nervous system and travels down a motor neuron to reach the muscle fiber.
2. Calcium release: The action potential triggers the release of calcium ions from the sarcoplasmic reticulum, a specialized network of membranes within the muscle fiber. Calcium ions bind to a protein called troponin, which is part of the thin filaments within the muscle fiber.
3. Cross-bridge formation: The binding of calcium to troponin causes a conformational change in the thin filaments, exposing binding sites for myosin, a thick filament protein. Myosin heads bind to these sites, forming cross-bridges between the thick and thin filaments.
4. Power stroke: When ATP (adenosine triphosphate) is hydrolyzed, the myosin heads undergo a conformational change, pulling the thin filaments towards the center of the sarcomere (the basic unit of muscle contraction). This is known as the power stroke.
5. Sliding filament theory: The power strokes of multiple myosin heads cause the thin filaments to slide past the thick filaments, resulting in the shortening of the sarcomere. This process occurs simultaneously in all sarcomeres within a muscle fiber, leading to muscle contraction.
6. ATP reattachment: After the power stroke, the myosin heads release the ADP (adenosine diphosphate) and phosphate molecules. ATP then binds to the myosin heads, causing them to detach from the thin filaments.
7. Relaxation: The calcium ions are actively pumped back into the sarcoplasmic reticulum, which causes the troponin to return to its original conformation. This blocks the myosin binding sites on the thin filaments, preventing further cross-bridge formation and allowing the muscle to relax.
It is important to note that this is a simplified explanation of the mechanism of muscle contraction, and there are many more intricate details and regulatory proteins involved in the process.
0
