Why Does Having a Fever Make You Feel Cold?

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During fever, why do we feel cold when our body temperature rises?

Nicole Van Groningen:

Anyone who has ever had the flu knows that fever isn’t uncomfortable because you feel hot—it’s uncomfortable because you feel freezing cold. You get goosebumps, you’re shivering, you’re piling on the covers.

Fever, also known as pyrexia, is defined as an elevation in body temperature above the normal range due to an increase in the body’s natural set point. Most people associate fever with infections, but fever can also frequently occur with autoimmune diseases, cancer, drug reactions, and even blood clots. Fever is not a direct result of these conditions, but rather a consequence of triggering the body’s inflammatory pathways. One key member of this inflammatory cascade is a group of molecules called pyrogens, which directly interact with the hypothalamus in the brain to produce fever.

The hypothalamus serves as the body’s thermostat. When triggered by pyrogens, the hypothalamus tells the body to generate heat by inducing shivering, goosebumps, and constriction of blood vessels near the surface of the skin. It even causes a subjective feeling of cold, which encourages behavioral responses to raise the body temperature, like reaching for the covers.

All of these things are adaptive when your body temperature falls below its usual set-point (about 98.6 degrees Fahrenheit), which typically occurs in cold weather. But they become abnormal in the setting of fever, when your hypothalamus signals to the body to raise its temperature well above the normal range.

If pyrogens suddenly disappear from the bloodstream, as is the case with intermittent fevers, the hypothalamus all of a sudden senses that things are way too hot, and tells the body to kick in its usual cooling-off mechanisms. That’s why people sweat profusely when their fever “breaks.”

This post originally appeared on Quora. Click here to view.

Does Washing Your Fruits and Vegetables Really Do Anything?

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Washing produce is one of those habits that some people follow religiously and others shrug off altogether. If you're someone who struggles to find the motivation to cook in the first place, you might fall into the latter group. But cleaning your fruits and vegetables at home isn't just an outdated precaution: As Popular Mechanics reports, a thorough rinse could mean the difference between a meal that nourishes you and one that leaves you sick.

Produce is one common carrier of norovirus—a foodborne viral infection that triggers such symptoms as nausea, vomiting, and diarrhea. There's no way to know whether your lettuce is contaminated with harmful bacteria before it hits your plate, but cleaning it with plain tap water does make it safer to eat. According to USA Today, rinsing produce is effective enough to remove 90 percent of the pathogens left on it by the growing, harvesting, and shipping process. Rinsing is also a good way to remove any of the visible matter you don't want eat, such as grit and soil.

Cleaning your fruits and vegetables is definitely an improvement over eating them straight from your crisper drawer, but be warned that this isn't a foolproof way to avoid food poisoning. Water won't remove all the microbes living on the surface of your food, and even an extremely thorough rinse isn't enough to make produce contaminated with potentially deadly bacteria like E. coli safe to eat. But that doesn't mean the risk outweighs the benefits of including produce in your diet.

If you have a pile of veggies that need to be prepared for dinner, the best way to make them safer for consumption is to rinse them under cold water and rub them in a bowl of water, starting with the cleanest items and progressing to the produce that's more soiled. Give all the food a final rinse before moving it to the cutting board. Peeling the outside of your produce and cooking it when possible is another effective way to kill or remove stubborn bacteria.

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What's the Difference Between Pigeons and Doves?

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To the layman, the difference between pigeons and doves has something to with color, maybe. Or location. Or general appeal (doves usually get much better press than pigeons do). But what’s the actual, scientific difference between doves and pigeons?

As it turns out, there isn’t one. Paul Sweet, the collection manager for the department of ornithology at the American Museum of Natural History, says the difference is more linguistic than taxonomic.

“The word dove is a word that came into English from the more Nordic languages, whereas pigeon came into English from French,” Sweet tells Mental Floss.

Both dove and pigeon refer to the 308 species of birds from the Columbidae family, Sweet says. There’s no difference between a pigeon and a dove in scientific nomenclature, but colloquial English tends to categorize them by size. Something called a dove is generally smaller than something called a pigeon, but that’s not always the case. A common pigeon, for example, is called both a rock dove and a rock pigeon.

“People just have their own classification for what makes them different,” Sweet says. “So in the Pacific, for example, the big ones might get called pigeons and the smaller ones might be called doves, but they’re actually more closely related to each other than they are to other things in, say, South America, that are called pigeons and doves.”

The difference boils down to linguistic traditions, so feel free to tell people you’re releasing pigeons at your wedding or that you’re feeding doves in the park. Scientifically speaking, you’ll be correct either way.

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