Ask Emily

28 07 2011

What causes ear wax?

You do! Ear wax comes in two types. One is a thick, yellow wax, known as the “wet” type. The other is a greyish, flaky kind of wax, known as the “dry” type and most common among people of Asian origin and American Indians. Either way, its job is to clean, disinfect, and moisturize your ears, which makes it sound like a beauty product.

In reality, it is a health product that your body makes as a line of defense against things that might harm you, from bacteria to fungi to, yes, insects. For this reason, unless your ear wax is causing a health problem, medical folk recommend that you just leave it alone. It will cycle through and out of your ear, renewing as it goes.

Which type you have—wet or dry—depends on a single mutation in a single gene. Researchers have noted that Asians, especially people from East Asia, have ear wax that is dry and whitish. People whose ancestors are from Europe and Africa almost invariably have ear wax that is sticky and brown or yellow. If a person doesn’t dump cholesterol and other smooth fatty things into their ear wax, then the wax will consist primarily of dead skin flakes, the dry type.

Whether or not you make one or the other traces back to a single change in a single gene. This gene encodes a protein that makes ear wax . . . wet. With the single change in the genetic alphabet, a person doesn’t make wet wax. Researchers have even used this single change to trace the course of human migration throughout the world. Who knew ear wax could be so informative and useful?

I know that a fever is when my body’s temp goes up, but why does it go up? Why is THAT the reaction to whatever is going on in my body?

Let’s start by talking about bedbugs. One of the potential treatments for a bedbug infestation is to turn up the heat in the house to a level that bedbugs can’t survive. Turns out, the little bloodsuckers aren’t too fond of high temperatures. Many things that invade your body are like those bedbugs. They’re pretty comfortable at your normal temperature, but high heat can disable the molecules that keep them functioning. That’s why, when your body’s defense system recognizes an invader, one response may be fever.

Cells that detect these invaders can send out chemical signals with a great name: pyrogens. Pyro, of course, refers to fire or flame, and these chemicals travel to the brain’s thermostat center. There, they signal the brain to readjust the body’s temperature . . . kicking it up a few notches.

To a point, this higher temperature is thought to make things uncomfortable for microbes while not harming you too much. When a strong fever response takes things too far, fever can be harmful, but you might be surprised at exactly how high a fever needs to be to cause harm to you. According to the experts, a fever won’t cause brain damage unless it exceeds a very specific 107.6 F (42 C).

This general defense—it doesn’t target the specific invader; instead, it just relies on wholesale heating—is one of your body’s first responses to infectious invaders like bacteria or viruses. Meanwhile, your body is likely also getting to work on more specific tactics to deal with the unwanted intruders.

Do you have a question for Emily? Send it to: pkids@pkids.org

By Emily Willingham

Image courtesy of CuriousGeoff


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