What is Muscular System and how does muscles work?

 Muscular System 

we know that our body make movement by the help of movable joints. Bones cannot move by themselves. The bones are attached which muscles and flexible like rubber plates. Muscles work by contraction and relaxation. White strong fibres which attach muscles with the bone are known as tendons. There are about 650 different muscles in our body. Muscles work in pairs. When one muscles contract the other is relax.

How does muscles work?

Muscles produce Movement in the body by pulling on the bones. Therefore, to separate muscles are needed to move a joint. When muscles contracts,it becomes shorter and thicker. When a muscle relaxes,it becomes longer and thinner. For example,the movement of arms are controlled by to muscles ---biceps and triceps.If we want to pull up our arms, the bicep which are are joined to the armsin front contract, while the triceps which are at the back of the arms relax . If you want to low down our arms ,our biceps relax while the triceps contract.