MICROANATOMY

Detailed explanation-1: -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-2: -Sliding Filaments In essence, during contraction a sarcomere shortens like a collapsing telescope, as the actin filaments at each end of a central myosin filament slide toward the myosin’s centre, as described below.

Detailed explanation-3: -During muscle contraction, the I band is reduced in size as the overlap between the thick and thin filaments increases. The Z-lines come together, and so the sarcomere shortens as well.

Detailed explanation-4: -Because sarcomeres are joined end to end throughout an entire muscle fiber, their simultaneous contraction shortens the entire muscle. Each myosin filament has numerous heads, and each actin filament has numerous binding sites.

Detailed explanation-5: -During contraction, the ends of the sarcomeres are pulled closer together, thus shortening the length of the muscle fiber.