The skin is the body's first line of defense. It acts as a physical barrier. When there are breaks in this barrier, such as cuts or sores, the body reacts to produce blood clots and a mesh work of fibrous tissue. The opening is thus blocked, which prevents germs that can cause disease, from entering the body. One important defensive mechanism involving blood is clotting.
Sometimes these invaders breach this first line of defense and enter the body. Some white blood cells called phagocytes, move out of the blood and to the infected areas. There they surround the invading micro-organisms, killing and removing them from the body before they can cause disease. This is our second line of defense.
The phagocytes can cope with any small, non-specific invasion by pathogens. If more dangerous, specific pathogens enter, then an immune response is activated. Another kind of white blood cell called lymphocytes that makes antibodies to attack, disarm, destroy and remove these foreign bodies. Any body that is foreign or different and causes antibody formation is called an antigen. This is our third line of defense.
When antigens such the measles virus, enter the body, lymphocytes recognize them and start to produce specific antibodies on a large scale to destroy the viruses. The immune response is very specific- only antibodies for that particular antigen are made.
Sometimes these invaders breach this first line of defense and enter the body. Some white blood cells called phagocytes, move out of the blood and to the infected areas. There they surround the invading micro-organisms, killing and removing them from the body before they can cause disease. This is our second line of defense.
The phagocytes can cope with any small, non-specific invasion by pathogens. If more dangerous, specific pathogens enter, then an immune response is activated. Another kind of white blood cell called lymphocytes that makes antibodies to attack, disarm, destroy and remove these foreign bodies. Any body that is foreign or different and causes antibody formation is called an antigen. This is our third line of defense.
When antigens such the measles virus, enter the body, lymphocytes recognize them and start to produce specific antibodies on a large scale to destroy the viruses. The immune response is very specific- only antibodies for that particular antigen are made.
