Immune or immune system includes defenses against pathogens in the body - viruses, bacteria, fungus, radiation, toxic substances, drugs. If pathogens are in small quantities, the immune system cope with the attack. There are some situations when the immune system is exceeded, is weak and needs help to cope with pathogens.
Immunity is a complex network composed of lymphoid organs (thymus, bone marrow, spleen, lymph nodes, appendix, tonsils), cells and molecules.
When the body is attacked by pathogens (also called antigens), the immune system make antibodies (immunoglobulins) that fight foreign substances. The immune system distinguishes between self (self) and foreign (nonself). Bones, muscles, tissues are their own structures, which are supported by our immune system. Foreign substances - viruses, bacteria, fungi, toxic substances - are always rejected immunity.
