Immune system
- Immunity is the protection against disease provided by the body's defence system or immune system. May be obtained actively or passively.
- Immune response is the action of lymphocytes in response to the entry of an antigen to the body.
- The body has many defences against pathogens entering e.g. skin, HCl in the stomach, ciliated epithelium in airways, blood clotting and white blood cells.
- An antigen is any molecule recognised by the body as foreign. They cover surface of pathogens and may be proteins, lipids, glycoproteins etc.
- An antibody acts against a particular antigen. It is made of globular glycoproteins and produced by B lymphocytes (part of the immune response). Antigens / antibodies are specific.
- The immune system depends on two types of white blood cells: phagocytes and lymphocytes.