Key area 4.2 Specific defences

Question	Answer
Specific defences Immune surveillance	A range of white blood cells which constantly circulate and monitor the tissue If tissue is damaged cells release cytokines which increase blood flow resulting in specific white blood cells to accumulate at the site of infection
Antigen	A molecule that can produce an immune response in the body
Specific defences Clonal selection theory	Lymphocytes have a single type of membrane receptor for one antigen. Antigen binding leads to repeated lymphocyte division resulting in a clonal population of lymphocytes
Specific defences T lymphocytes	A.K.A Helper T cells These cells secrete cytokines which activate B lymphocytes and phagocytes.
Specific defences T lymphocytes	A.K.A Cytotoxic T cell This destroys infected cells by apoptosis
Specific defences B lymphocytes	The cytokines released by Helper T cells stimulate specific B cells to clone themselves. Each clone produces a specific antibody molecule that will recognise a specific antigen surface molecule and pathogen or toxin.

Resource summary

	Created by Dayna Underwood about 8 years ago