How is the immune system able to find and recognize such small invaders in the vast area of the body? There are three main reasons that the immune system is able to accomplish this feat. The first reason that the immune system is so effective at finding and recognizing invaders so well is because it sends out an exceptionally large number of immune cells that continuously patrol every inch of the body looking for invaders. These patrolling immune cells could be considered the Army. This army of soldier cells called phagocytic cells travel through the blood stream searching for pathogens. You were born with one division of this army, called the innate immune system and acquired the second division, the adaptive immune system, after birth through exposure to pathogens. These immune cells are able to immediately recognize certain microbes and pathogens and then destroy them.
The second reason that the immune system is able to find and recognize invaders is because each of these patrolling immune cells has many hyper- sensitive recognition receptors. The receptors could be thought of as little hands that cover each cell. A receptor is able to feel and touch, which allows it to recognize intruders. Each cell carries the equivalent of a thousand receptors or hands. As a result, collectively, these immune cells are able to effectively and to carefully patrol vast areas of the body, by searching, touching, feeling, and thus finding intruders. The third reason that the immune system is able to find and recognize intruders so well are because theses immune cells are very intelligent. Each cell has a very large nucleus , or brain, for thinking. The nucleus is filled with DNA. This brain power allows the immune cell the ability to distinguish between the self and intruder. In conclusion, the reason that the immune system is able to search and find invaders so well is because it is able to send out large numbers of incredibly clever immune cells to patrol the body with hypersensitive receptors that can and find invaders.