The Immune System
Self vs. Non-Self
Every cell in our body has a unique set of proteins. When a phagocyte or T-Cell encounters another cell, it checks the set of proteins to see if they match the body. If they don't, it will act and attack the foreign cell. The cells also destroy self-organizing immature B-Cells throughout the body.
Two Types of Responses
The body responds to foreign invaders through two ways; Innate immunity and adaptive immunity. Innate immunity deals with the nonspecific defense mechanisms that first come into play against foreign antigens such as physical barriers like skin and chemicals in blood. Adaptive immunity deals with a specific response to the antigen. The body studies the particle and then creates specific immune cells to eliminate it.
Roles of Immune Cells
The immune cells are important to the overall health of the body and are responsible for removing foreign particles and organisms that could potentially cause harm. Some cells are uses specifically for reactions to these particles while others patrol the body through the blood stream. Other cells cause inflammation of tissue as a defense against foreign objects in the body.
Difference Between Active and Passive Immunity
Active and Passive immunity can come both naturally and artificially. Natural active immunity occurs when the person is exposed to a pathogen, develops the disease, and becomes immune because of the primary immune response. Artificial active immunity can be acquired from vaccines which causes the primary immune response. Artificial passive immunity is short term and comes from injections of antibodies that are not naturally produced. Natural passive immunity occurs during pregnancy when antibodies are passed down from mother to child.
Vaccines work by mimicking an actual infection. The body responds like it would with a normal infection and works to learn about and eliminate the foreign molecules. Once the body has succeeded, the information it gathered is stored and can be used if the body is exposed to the foreign particles again in the form of the actual infection as opposed to the vaccine. Taking a vaccine allows the body to gain the information it needs without going through the symptoms of the disease because a weakened version of the infection is introduced with the vaccine.