Question

How muscles are able to contract and relax?

Answer 1

Answer:

Muscle fibers can contract because they are made of proteins, called actin and myosin, that form long filaments (or fibers). When muscles contract, these protein filaments slide or glide past one another, shortening the length of the cell. When your muscles relax, the length extends back to the previous position.

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Answer 2

Answer:

Muscle fibers can contract because they are made of proteins, called actin and myosin, that form long filaments (or fibers). ... When your muscles relax, the length extends back to the previous position. Nearly all movement in the body is the result of muscle contraction. You can control some muscle movements.

Explanation:

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