The Immune Response

This lesson covers the specific immune response as required by the Edexcel GCSE Combined Science specification (1SC0). You need to understand the role of white blood cells (phagocytes and lymphocytes), the processes of phagocytosis, antibody production and antitoxin production, and the concept of memory cells.

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The Second Line of Defence

If pathogens get past the non-specific defences (skin, mucus, stomach acid), the body activates the immune response — a targeted attack by white blood cells (also called leucocytes).

White blood cells are produced in the bone marrow and travel throughout the body in the blood and lymphatic system. They can also leave blood vessels and move into tissues where infection is occurring.

There are two main types of white blood cell you need to know:

1. Phagocytes — engulf and digest pathogens
2. Lymphocytes — produce antibodies and antitoxins

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Phagocytes and Phagocytosis

Phagocytes are white blood cells that destroy pathogens by engulfing and digesting them. This process is called phagocytosis.

The Process of Phagocytosis