The Immune System

The immune system is the body's defence against pathogens. Pathogens are microorganisms that cause disease and can be viruses, bacteria, fungi or protoctists.When the pathogens gain entry into the body, they rapidly multiply in number, using the body's resources. They destroy cells or produce toxins which are metabolites that interfere with the body's cellular activities.If not destroyed the pathogens will cause death to the organism.The immune system is a set of processes that destroys the pathogens.If the body's immune system overwhelms the pathogen the individual recovers from the disease.If the number of pathogens increases faster than they can be destroyed, the individual could die from the disease if not treated.The immune system consists of white blood cells produced in the bone marrow and circulating the body in tissue fluid, blood and the lymphatic system.