Our body works like a machine. It performs many functions at the same time. There is different system in our body to perform different functions. The digestive system helps in digestion and absorption of the food we take. The absorbed food supplies energy with the help of respiratory system and circulated system. The nervous system helps in carrying impulses. The excretory system eliminates the waste materials produced in our body. All these systems and internal organs need protection from injury and shock.

If you press your hands, legs, back, head and shoulders, you will feel hard structures. These hard structures are bones. They form the skeletal system. It protects the systems and internal organs from injury.

The bony framework of the body is called the skeleton or skeletal system. The skeleton consists of bones and cartilage. Externally the skeletal system is covered with muscles and skin. The human skeleton is strong and hard.

If your body is strong, you will live long with good health.

To keep the bones and muscles in good shape and healthy condition, we must maintain good postures while doing different types of work. We should always keep the backbone straight. We must do good exercises regularly. We should develop good eating habit. We should always take nutritive food in required quantities. Bad habits like smoking and chewing tobacco result lung cancer and mouth cancer respectively.

It is not good to sit beside the people who are smoking. If you do so, it results in passive smoking and spoils your health.

Some people get themselves addicted to certain substance like heroin, cocaine, marijuana etc. they are harmful because they cause damage to the nervous system. People who get addicted to these drugs become slaves to them because they cannot give up such habits.