Put the steps of muscle contraction in order from first (1) to last (5). the sarcomere shortens. calcium ions are released by a nerve cell. the sarcomere is relaxed. actin and myosin overlap completely. actin and myosin are activated.

Explanation:

For muscle contraction to occur it is necessary that the brain first sends signals to motor neurons that will quickly establish contact with muscle fibers.

At that time, the axons close to the muscle fibers will lose the myelin sheath, as a result of which, the axons will dilate forming a kind of plaque called the motor plaque. The main function of this motor plate is to allow the motor nerves to connect to the muscles.

Simultaneously, the nervous impulse will reach the aconic terminations of the motor nerves. This will cause the release of acetylcholine over the muscle fibers causing an action potential to occur. After that, the actin and misin filaments contract, as a result the sarcomere becomes decreased and as it decreases it causes muscle contraction.

In summary, muscle contraction happens as follows:

a "theory" a suggestion that is not 100 % accurate, or a figure. some people say its a theory because they of all the passed theory's about one subject. it depends sometimes theory might be accurate and sometimes they are.

the generally accepted parts of modern cell theory include: all known living things are made up of one or more cells. all living cells arise from pre-existing cells by division. the cell is the fundamental unit of structure and function in all living organisms.