The body's own defence

The idea

The natural ability of the body to fight diseases is called immunity, and the special system of the body that helps fight diseases is the immune system.

Same place, different result

Some people fall sick more often than others, even though they live in a similar environment and meet the same germs.

Why do you think this happens?

• Bodies differ in how well they fight disease
• Germs choose who to visit
• It is only luck

Same room, same germs

Riya and Sam are in the same room. Let the germs reach both of them.

Immunity

The natural ability of the body to fight diseases is called immunity. The special system of the body that helps fight diseases is the immune system.

• Word | Meaning
• Immunity | The natural ability of the body to fight diseases
• Immune system | The special system of the body that helps fight diseases

Notes

Immunity is the natural ability of the body to fight diseases. The immune system is the special system that helps fight diseases.

Check yourself

What is the natural ability of the body to fight diseases called?

Which system of the body helps fight diseases?

Two children share a room with the same germs. One stays well and the other falls ill. What may be different?

• Immunity — correct. Yes. Immunity is the body's natural ability to fight diseases.
• A pathogen. A pathogen is a disease-causing organism.
• A vector. A vector is an insect that carries pathogens.
• The immune system — correct. Yes. It is the special system that helps fight diseases.
• The digestive system. The digestive system breaks down food.
• The respiratory system. The respiratory system helps us breathe.
• Their immunity — correct. Yes. Bodies differ in their natural ability to fight diseases.
• The germs. The germs are the same in both cases.
• The room. They share the same room.