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IMMUNE SYSTEM. HEALTHY LIFE STYLE A sound mind in a sound body!
What Is the Immune System and What Does It Do
The immune system defends people against germs and microorganisms every day.
Sometimes problems with the immune system can lead to infection and disease.
About Cells There are two basic types of leukocytes: •the phagocytes are cells that chew up invading organisms; •the lymphocytes are cells that allow the body to remember and recognize previous invaders and help the body destroy them.
Leukocytes are produced or stored in many locations in the body, including the thymus, spleen, and bone marrow. For this reason, they are called the lymphoid organs. There are also groups of lymphoid tissue in the body, primarily in the form of lymph nodes, that house the leukocytes. The leukocytes circulate through the body between the organs and nodes by means of the lymphatic vessels. Leukocytes can also circulate through the blood vessels. In this way, the immune system works in a coordinated manner to monitor the body for germs or substances that might cause problems.
All of these specialized cells and parts of the immune system offer the body protection against disease. This protection is called immunity. Humans have three types of immunity — innate, adaptive, and passive.
Innate Immunity Everyone is born with innate immunity, a type of general protection that humans have. Many of the germs that affect other species don't harm us. For example, the viruses that cause leukemia in cats or distemper in dogs don't affect humans. Innate immunity works both ways because some viruses that make humans ill — such as the virus that causes HIV/AIDS — don't make cats or dogs sick either.
Innate immunity also includes the external barriers of the body, like the skin and mucous membranes (like those that line the nose, throat, and gastrointestinal tract), which are our first line of defense in preventing diseases from entering the body. If this outer defensive wall is broken (like if you get a cut), the skin attempts to heal the break quickly and special immune cells on the skin attack invading germs.
Adaptive Immunity We also have a second kind of protection called adaptive (or active) immunity. This type of immunity develops throughout our lives. Adaptive immunity involves the lymphocytes and develops as children and adults are exposed to diseases or immunized against diseases through vaccination.
Passive Immunity Passive immunity is "borrowed" from another source and it lasts for a short time. For example, antibodies in a mother's breast milk provide an infant with temporary immunity to diseases that the mother has been exposed to. This can help protect the infant against infection during the early years of childhood.
Everyone's immune system is different. Some people never seem to get infections, whereas others seem to be sick all the time. As people get older, they usually become immune to more germs as the immune system comes into contact with more and more of them.
Things That Can Go Wrong With the Immune System Disorders of the immune system can be broken down into four main categories: immunodeficiency disorders (primary or acquired); autoimmune disorders (in which the body's own immune system attacks its own tissue as foreign matter); allergic disorders (in which the immune system overreacts in response to an antigen); cancer of the immune system.
And if you're lucky enough to be healthy, you can help your immune system keep you that way by washing your hands often to avoid infection, eating right, getting plenty of exercise, and getting regular medical checkups.
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