The thymus is a gland in the chest which turns ordinary white blood cells into special T-cells that fight harmful microbes During an infection, lymph nodes may swell up with white blood cells that have swallowed up germs The adenoids in the nose arc one of the body’s defense centers, releasing cells to fight infections If you get a throat infection the tonsils release cells to fight it The spleen not only destroys worn-out red blood cells, but also helps make antibodies and phagocytes Lymph glands in the groin often swell up as the body fights an infection Sebaceous glands in the skin ooze an oil that is poisonous to many bacteria.
The body’s range of interior defenses against infection is amazingly complex. The various kinds of white blood cells and the antibodies the defenses make are particularly important.
The AIDS virus, HIV, attacks the body’s immune cells and prevents them from dealing with infections.
The immune system is the complicated system of defenses that your body uses to prevent or fight off attack from germs and other invaders.
Your body has a variety of barriers, toxic chemicals and booby traps to stop germs entering it. The skin is a barrier that stops many germs getting in, as long as it is not broken.
Mucus is a thick, slimy fluid that coats vulnerable, internal parts of your body such as your stomach and nose. It also acts as a lubricant (oil), making swallowing easier.
Mucus lines your airways and lungs to protect them from smoke particles as well as from germs. Your airways may fill tip with mucus when you have a cold, as your body tries to minimize the invasion of airborne germs.
Itching, sneezing, coughing and vomiting are your body’s ways of getting rid of unwelcome invaders. Small particles that get trapped in the mucous lining of your airways are wafted out by tiny hairs called cilia.
The body has many specialized cells and chemicals which fight germs that get i nside you.
Complement is a mixture of liquid proteins found in the blood which attacks bacteria.
Interferons are proteins which help the body’s cells to attack viruses and also stimulate killer cells (see lymphocytes).
Certain white blood cells are cytotoxic, which means that they are poisonous to invaders.
Phagocytes are big white blood cells that swallow up invaders and then use an enzyme to dissolve them (see antibodies). They are drawn to the site of an infection whenever there is inflammation.