Difference between revisions of "White blood cell"
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| − | '''White blood cells''' are a component of [[blood]]. As part of the body's [[immune system]], their function is to protect the body from disease and infection. White blood cells come in several varieties, each with a different role to play in neutralizing harmful foreign substances. White blood cells, like all [[blood cells]], are produced in the [[bone]] marrow. | + | '''White blood cells''' are a component of [[blood]]. As part of the body's [[immune system]], their function is to protect the body from disease and infection. White blood cells come in several varieties, each with a different role to play in neutralizing harmful foreign substances. White blood cells, like all [[blood cells]], are produced in the [[bone]] marrow. |
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| + | They are also known as leukocytes. There are five main types of leukocytes, and these types are produced from immature cells in the [[lymphatic system]] in response to the body's needs. For example, infection with bacteria will cause more [[macrophage]]s to be produced and fewer NK cells, in response to "alarm signals" called [[chemokine]]s. Macrophages then exit the bloodstream, migrate towards the site of infection, and attempt to neutralize the invading pathogens. Others begin producing antibodies or recruit other systems to help. | ||
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| + | The immune system of all [[vertebrates]] has [[memory]], which in this context means that it keeps a record of invaders it has previously encountered. Immune memory is not completely understood, but involves the cells that contributed most to fighting off the infection being stored away in the bone marrow. This system is why you will not usually get [[chickenpox]] if you have already had it, and is also why vaccines work (the vaccine looks similar to a pathogen such as [[polio]], so the immune system will "remember" it and then be ready if it should ever encounter the real thing). | ||
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==See Also== | ==See Also== | ||
Revision as of 04:24, October 30, 2011
White blood cells are a component of blood. As part of the body's immune system, their function is to protect the body from disease and infection. White blood cells come in several varieties, each with a different role to play in neutralizing harmful foreign substances. White blood cells, like all blood cells, are produced in the bone marrow.
They are also known as leukocytes. There are five main types of leukocytes, and these types are produced from immature cells in the lymphatic system in response to the body's needs. For example, infection with bacteria will cause more macrophages to be produced and fewer NK cells, in response to "alarm signals" called chemokines. Macrophages then exit the bloodstream, migrate towards the site of infection, and attempt to neutralize the invading pathogens. Others begin producing antibodies or recruit other systems to help.
The immune system of all vertebrates has memory, which in this context means that it keeps a record of invaders it has previously encountered. Immune memory is not completely understood, but involves the cells that contributed most to fighting off the infection being stored away in the bone marrow. This system is why you will not usually get chickenpox if you have already had it, and is also why vaccines work (the vaccine looks similar to a pathogen such as polio, so the immune system will "remember" it and then be ready if it should ever encounter the real thing).