White blood cells

1. Their main job is to fight infection

White blood cells are part of the immune system.
They protect the body from pathogens such as bacteria and viruses.

2. There are different types of white blood cells

The main types you should know:

• Phagocytes – engulf and digest pathogens (phagocytosis)

• Lymphocytes – produce antibodies and antitoxins

Different types have different roles in defending the body.

3. They have a nucleus

Unlike red blood cells, white blood cells have a nucleus.
Some (like neutrophils) have a multi-lobed nucleus, which helps them move through tissues.

4. They can leave the bloodstream

White blood cells can change shape and squeeze through capillary walls to reach infected tissues.
This allows them to attack pathogens at the site of infection.

5. They are produced in the bone marrow

White blood cells are made in the bone marrow.
Some (like lymphocytes) mature in other parts of the body such as lymph nodes or the thymus.