According to the sliding filament theory, how does muscle contraction occur?

A. Both thick and thin filaments shorten as the muscle contracts.

B. A bands bunch up and shorten as myosin heads attach to thin filaments.

C. Myosin heads attach and detach from thin filaments, causing then filaments to shorten.

D. Myosin heads form cross bridges and pull thin filaments, causing them to slide.

the presence of acetocholene causes calcium to be released causing depolarization of the sarcoplasmic reticulum and changing its shape. the myofilaments together with actin allows the myosin to form cross bridges along the muscle fibers and releases ATP for movement of the muscle.

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genewho genewho · Answer 2 · 2021-11-11T19:06:19+01:00

According to the sliding filament theory, muscle contraction occurs when myosin heads form cross bridges and pull thin filaments, causing them to slide.

The sliding filament theory explains the way muscles contract; each sarcomere (functional unit of muscle) contains superimposed thin (actin) and thick (myosin) filaments that are interconnected by cross bridges.

Each myosin head contains 2 binding sites on it: the first for an ATP molecule and the other for actin.

Actin molecules serve as if it were a rope, to which the myosin head is attached.

During a force blow, the movement of the flexible myosin cross-bridges pushes the actin filaments toward the center of the sarcomere.

At the end of a force blow each myosin head releases the actin that is bound to it, then oscillates back and binds to a new actin molecule, to start another force blow.

This cycle is repeated an infinity of times, when the muscle contracts, myosin, accomplishes this task by converting the chemical energy of the ATP bond into mechanical energy.

Therefore, we can conclude that according to the sliding filament theory, muscle contraction occurs when myosin heads form cross bridges and pull thin filaments, causing them to slide.

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