1 Phagocytes and lymphocytes are the cells of the immune system.2 The diagram shows how to recognise phagocytes and lymphocytes in microscope slides and photomicrographs of blood.3 Phagocytes originate in the bone marrow and are produced there throughout life. There are two types: neutrophils that circulate in the blood...

A person is immune to a disease if the pathogen that causes the disease is unable to reproduce in the body and cause illness. This happens when the body already contains, or is able rapidly to make, large quantities of antibodies against the antigens associated with the pathogen.ImmunityActive immunity occurs when...