ANATOMY

Detailed explanation-1: -According to this theory, muscle contraction takes place by sliding of thin filaments over thick filaments. The signal that initiates the muscle contraction is sent by the central nervous system with the help of a motor neuron (nerve cell that passes from the central nervous system to the muscle).

Detailed explanation-2: -Sliding Filament Model of Contraction For a muscle cell to contract, the sarcomere must shorten. However, thick and thin filaments-the components of sarcomeres-do not shorten. Instead, they slide by one another, causing the sarcomere to shorten while the filaments remain the same length.

Detailed explanation-3: -By studying sarcomeres, the basic unit controlling changes in muscle length, scientists proposed the sliding filament theory to explain the molecular mechanisms behind muscle contraction. Within the sarcomere, myosin slides along actin to contract the muscle fiber in a process that requires ATP.

Detailed explanation-4: -According to the sliding filament theory, a muscle fiber contracts when myosin filaments pull actin filaments closer together and thus shorten sarcomeres within a fiber. When all the sarcomeres in a muscle fiber shorten, the fiber contracts.

Detailed explanation-5: -This process is fueled by ATP, which acts as an energy source. ATP is hydrolysed in the heads of molecules of myosin causing a change in the shape of the head and binding to actin filaments.