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.
