Essay On Immune System

The Immune System: The Body's Three Lines of Defence

The immune system has the important job of protecting the body from foreign invaders. It is made up of a network of cells (including white blood cells), tissue and organs. The foreign invaders the immune system fight include viruses, bacteria, microbes and pathogens. In order to stop these foreign invaders, there is a process known as immune response that attacks in three different lines of defence. Without this immune response, the body would be constantly under invasion by pathogens trying to attack and induce illness.

These three lines of defence that make up the body's immune response are the physical and chemical barriers, the non specific response and the specific response. These

However, it is only a certain kind of white blood cell that comes out in the non specific response, and it is called a phagocyte - meaning 'cells that eat'. In a process known as phagocytosis, phagocytes can envelope any kind of pathogen within the body and, whilst the pathogen is inside the phagocyte, it can destroy it.

The Third Line of Defence:

The third line of defence in the body's immune response is the specific response. If there are still any pathogens in the body after the first responses have occurred they are targeted according to their type by the third defence. This third defence is a specific immune response, and it produces and binds protein molecules know as an antibodies to specifically target an antigen - which is typically a pathogen itself or a marker molecule on the surface of the pathogen. When the body becomes infected with a pathogen, certain antibodies are created by the third defence to attack that pathogen. Once these antibodies have been produced to fight off specific antigens they are remembered by the body and if the same antigen tries to invade again, it is instantly targeted and destroyed, as the body is now