White blood cells

Definition

White blood cells (WBCs) are crucial components of the immune system, responsible for defending the body against infections and foreign invaders. They circulate in the blood and are produced in the bone marrow.

5 Must Know Facts For Your Next Test

1. White blood cells can be classified into five major types: neutrophils, lymphocytes, monocytes, eosinophils, and basophils.
2. Neutrophils are the most abundant type of white blood cell and are often the first responders to bacterial infections.
3. Lymphocytes include B cells and T cells, which play key roles in adaptive immunity by producing antibodies and killing infected cells.
4. A high white blood cell count can indicate an infection or inflammation, while a low count may suggest bone marrow problems or autoimmune diseases.
5. White blood cells use chemotaxis to move towards sites of infection or injury by following chemical signals.

Review Questions

• What are the five major types of white blood cells?
• How do neutrophils respond to bacterial infections?
• What roles do B cells and T cells play in adaptive immunity?

Related terms

Red Blood Cells: Cells that transport oxygen from the lungs to tissues and carbon dioxide from tissues to the lungs.

Platelets:

Small cell fragments involved in blood clotting to prevent excessive bleeding.

Bone Marrow: The soft tissue inside bones where blood cells, including white blood cells, are produced.