In the sliding filament theory, what happens to the thick and thin filaments during muscle contraction?

• A. The thin filaments are broken down, and the thick filaments remain unchanged.
• B. The thick and thin filaments slide past each other, increasing overlap.
• C. The thick and thin filaments shorten in length.
• D. The thick filaments are pulled apart, while the thin filaments remain stationary.

Answer: (B)

Verified step by step guidance

1. Begin by understanding the sliding filament theory, which explains the mechanism of muscle contraction at the molecular level.
2. Identify the components involved: thick filaments composed of myosin and thin filaments composed of actin.
3. During muscle contraction, the myosin heads on the thick filaments bind to the actin on the thin filaments, forming cross-bridges.
4. The myosin heads then pivot, pulling the thin filaments toward the center of the sarcomere, which increases the overlap between the thick and thin filaments.
5. Note that the filaments themselves do not shorten; instead, they slide past each other, resulting in the shortening of the sarcomere and thus muscle contraction.