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Health and hygiene

Diseases And Their Causes

Have you ever wondered that if the air contains so many microorganisms, then why do we not get infected by these microbes?

The body has many natural ways to prevent diseases. They defend the body against diseases and are called natural defence system of the body. There are various organs in our body which prevent the entry of disease causing microorganisms in our  body.

The body has its own defence mechanism through which it tries to prevent the entry of microorganisms. There are two lines of defence in the body. They are:

  • Non-specific defence mechanism
  • Specific defence mechanism

Non-Specific Defence Mechanism

These mechanisms do not allow the entry of microorganisms in the body. They are found in

  • Skin − It keeps away the microbes and prevents their entry in our body.

  • Mucus membrane in nose − It has cilia which trap the dust and microbes that may enter otherwise in our body as we breathe. It forms a sticky coating to trap the bacteria.

  • Tears − Tears wash away the bacteria out of our eyes.

  • Hydrochloric acid in the stomach − It kills the bacteria that enter the stomach along with food.

  • Blood cells − They destroy the germs present in the blood. For example: WBCs.

  • Hairs: Hairs in the nose.

The skin, mucous membranes, hair, etc. form the first line of defence while W.B.C forms the second line of defence.



Health and Diseases

Solved Examples


Example 1

Can you explain the difference between a healthy and a disease-free state of the human body?


The state of not having any disease is not the same as being healthy. Good health is the ability of an individual to realize his or her full potential. Consider, for example, an athlete who is tired after running about hundred metres. The athlete cannot be called a diseased person. However, he is not healthy either. Therefore, one can have poor health without having any identifiable disease.

Types of Health

Personal Health and Community Health 

Did You Know?

  • The word ‘hygiene’ is derived from the Greek word ‘Hygieia. In Greek mythology, Hygieia is the goddess of health, cleanliness and sanitation.

Concept Builder

Personal hygiene

Here are certain healthy habits that we all must follow to maintain personal hygiene.

  • Bathing regularly to remove sweat and…

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