Question

How are muscles able to contract

Answer 1

Answer:

Muscles contract through a chain process of electrochemical signalling between the nervous system and muscles.

Explanation:

The muscle contraction is initiated by the nervous system by sending a signal. This signal also referred to as action potential travel through the motor neuron. This motor neuron releases a chemical signal to muscle when the electrical signal carried by it reaches the neuromuscular junction (a junction where motor neuron meets the muscles).  

The chemical message referred to as neurotransmitter binds to the receptors present on the muscle fibers. These receptors causes the influx of sodium ion which in turn trigger the release of calcium ion thereby initiating the contraction of muscles.

Answer 2

Answer:

Muscles are able to contract due to myosin's ability to “break down” (hydrolyze) ATP.

Explanation:

In muscle contraction, sarcomere shortening occurs: actin filaments “glide” over those of myosin, thanks to certain binding points that form between these two filaments, leading to the formation of actomyosin.

For this slip to happen, a large amount of two important elements participate: Ca ++ and ATP ions. In this case it is up to the myosin molecule to “break down” (hydrolyze) the ATP, releasing the energy needed for contraction to occur.