What do muscles need so they can contract?

Answer 1

i know that you need a nerve impulse the second i think is calcium and i don't know what the third is.

Movement is initiated by muscles (forces) moving about levers (bones, etc humerus) about axes (our joints). In order for a muscle to contract a neural impulse in needed and in the abssence of a neural impulse calcium is reabsorbed into the; sarcoplasmic reticulum ( part of a single muscle fibre)

Answer 2

Muscles are mainly composed of alternating rows of myosine protein filaments and actin protein filaments. When the muscle is relaxed those rows are least overlapped. When the nervous impulse commands the muscle to contract these rows overlap making the muscle shorter in length and causing a mechanical function.

The muscle contraction process first happens by a motor neuron being activated. This produces an action potential that passes outward in a ventral root of the spinal cord where it is conveyed to a motor end plate on each muscle fiber. The action potential causes the release of packets of acetylcholine into the synaptic clefts on the surface of the muscle fiber. The acetylcholine causes the electrical resting potential under the motor end plate to change, and this then initiates an action potential which passes in both directions along the surface of the muscle fiber. At the opening of each transverse tubule onto the muscle fiber surface, the action potential spreads inside the muscle fiber. At each point where a transverse tubule touches part of the sarcoplasmic reticulum, it causes the sarcoplasmic reticulum to release Ca+2 ions. The calcium ions result in movement of troponin and tropomyosin on their thin filaments, and this enables the myosin molecule heads to "grab and swivel" their way along the thin filament. This is the driving force of muscle contraction.

Answer 3

alot of things but i ATP a good place to start

Answer 4

Actonin