The Immune System Essay -- essays research papers

The Immune SystemThe immune system is a group of cells, molecules, and tissues that helpdefend the body against diseases and other unwholesome invaders. The immune systemprovides protection against a variety of potentially damaging substances thatcan invade the body. These substances include disease-causing organisms, suchas bacteria, fungi, parasites, and viruses. The bodys ability to resist theseinvaders is called immunity. A key feature of the immune system is its abilityto destroy foreign invaders while leaving the bodys own profound tissues alone.Sometimes, however, the immune system attacks and damages these healthy tissues.This reaction is called an autoimmune answer or autoimmunity.The immune system is composed of many parts that work together to fightinfections when pathogens or poisons invade the humans body. Pathogens aredisease-causing organisms such as bacteria and viruses. The immune systemreacts to foreign substances through a series of steps know as the immuneres ponse. some(prenominal) agent perceived as foreign by a bodys immune system is called anantigen. Several types of cells may be involved in the immune response toantigens.When an antigen enters the body, it may be partly neutralized bycomponents of the innate immune system. It may be attacked by phagocytes or byperformed antibodies that act together with the balance system. The humanimmune system cont...