GENERAL HISTOLOGY

Detailed explanation-1: -According to the sliding filament theory, the myosin (thick filaments) of muscle fibers slide past the actin (thin filaments) during muscle contraction, while the two groups of filaments remain at relatively constant length.

Detailed explanation-2: -Muscle contraction occurs when sarcomeres shorten, as thick and thin filaments slide past each other, which is called the sliding filament model of muscle contraction. ATP provides the energy for cross-bridge formation and filament sliding.

Detailed explanation-3: -The sliding filament theory explains the process of muscle contraction during which the thin filaments slide over the thick filaments, which shortens the myofibril. Each muscle fibre has an alternate light and dark band, which contains a special contractile protein, called actin and myosin respectively.

Detailed explanation-4: -The sliding filament contraction occurs in the sarcomere region. The myosin filaments ratchet over actin filaments contracting the sarcomere. The I and H bands within the sarcomere compress and expand to facilitate the movement. The myofilaments do not expand and contract on their own.