Do you know that almost half of your body weight is made up of muscles! For example, if you weigh 40 kilograms, about 20 kilograms constitute pure muscle!
Muscles are the part of our body that allow us to move. They are made up of special tissues that can contract when they receive a signal from the brain.
The muscles are attached to bones by stretchable tissues called tendons. When the muscles contract they pull on the tendons which pull on the bones and cause our arms and legs to move.
There are about 650 muscles in our body and most of them are always at work. Some muscles are controlled by us. Others do their work without our thinking about them at all.
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Muscle actions can be voluntary or involuntary.
Involuntary muscles, found in the heart, diaphragm and intestines, are automatically controlled by the brain. You don’t have to think about making them work. For example, the heart beats about 60 to 80 times every minute without you having to think about it! All the actions by muscles are controlled by our brain. It sends and receives signals through the nerves.
Muscles in our arms and legs can be controlled by us are voluntary muscles.
The muscles that move your skeleton work in pairs. The reason for this is simple. Muscles pull, but they cannot push. To bend the arm, for example, the biceps muscle pulls the forearm up. To straighten the arm, the biceps’ teammate, the triceps, pulls the forearm down. Feel this for yourself. Your upper arm muscles get fatter as they pull, or contract, and thinner as they relax.