Physical Evidence That Supports the Sliding Filament Theory of Muscle

Question

Physical evidence that supports the sliding filament theory of muscle contraction includes
A) constant distance between Z lines during contraction.
B) decreased width of the H band during contraction.
C) increased width of the I band during contraction.
D) decreased width of the A band during contraction.
E) the I band + H band distance is constant during contraction.

Accepted Answer

The sliding filament theory of muscle contraction is supported by the observation that the width of the H band decreases during contraction. This occurs because the actin filaments slide closer together, shortening the muscle without changing the length of the filaments themselves.