When a Skeletal Muscle Contracts, What is Happening at the Level

Question

When a skeletal muscle contracts, what is happening at the level of the muscle proteins?
A)Thick filaments shorten.
B)Thin filaments slide relative to thick filaments.
C)Thin filaments depolymerize to shorten.
D)Calcium ions bind to tropomyosin, which allows actin to bind to myosin.
E)Tropomyosin binds to troponin, which allows calcium to bind to actin.

Accepted Answer

When a skeletal muscle contracts, the thin filaments slide relative to thick filaments. This is due to the myosin heads of the thick filaments binding to the actin of the thin filaments and pulling them towards the center of the sarcomere. This sliding mechanism is known as the sliding filament theory of muscle contraction.