"Why don't we get goose bumps on the face?"
We do get them on our cheeks, says Jessica Krant, MD, a board-certified dermatologist and assistant clinical professor at SUNY Downstate Medical Center. Goose bumps, or cutis anserine, occur where we have hair--pretty much everywhere except for our palms and soles of feet, Krant says. She breaks down the process: Each hair follicle contains a microscopic muscle called arrectores pilorum that contracts in response to the sensation of cold, or the feelings of fear or excitement. The reason most of us, especially women, don't notice goose bumps on our face is because the peach fuzz there is usually fine and short, and our facial skin muscles are less robust than those in our arms and legs. Krant adds that if you find goose-pimply bumps on any part of your body that don't seem to be affected by fear or temperature, you might have keratosis pilaris, an eczema-like condition caused by inflamed follicles.
"Does being overweight mean you'll get pregnant easily?"
We don't see a lot of images of fertility goddesses as skinny stick figures. And it's true that underweight women make a form of estrogen that can be too weak for successful conception, according to the American Society for Reproductive Medicine (ASRM). While obese women often have an overabundance of estrogen, this can affect their cycle to the point that they stop ovulating. Excess weight can influence fertility in other ways, too: A 2007 Dutch study of more than 3,000 couples (without any known ovulation problems) found that women with a body mass index of 30 or higher had significantly lower probability of becoming pregnant naturally, when compared with women with BMIs of between 21 and 29. This is why the ASRM stresses the importance of maintaining a healthy weight for those trying to conceive. By the way, having full hips won't even provide an advantage during childbirth; "It's the front-to-back dimension that creates the tightest squeeze," discovered Nathanael Johnson while exploring the science and history of childbirth (among other biological processes) for his book All Natural. So a tall, average-weight woman has the best chance of getting pregnant naturally and giving birth more easily.
"Why don't people who take nitroglycerin for their heart blow themselves up?"
This query usually exposes a childhood fascination with Roadrunner cartoons, says Billy Goldberg, MD, a New York emergency room physician and the co-author (with Mark Leyner) of two books about health trivia ("the kind of stuff everyone wants to know, but that doctors aren't taught in medical school," Goldberg says). For those who've forgotten: The coyote would blow himself up with explosive nitroglycerin--the same substance used in heart medication. In the commonly prescribed pill form, nitroglycerin helps increase blood flow to oxygen-deprived areas of the heart by dilating blood vessels. The medicinal dose of nitroglycerin in heart medication is infinitesimal compared with the amount in a stick of dynamite, explains Goldberg in Why Do Men Fall Asleep After Sex? It's also highly diluted for safe handling.
"Can sunshine make you sneeze?"
Goldberg says this is one of his favorite questions--mostly because he assumed it was too ridiculous to be true. While writing Why Do Men Have Nipples?, Goldberg and Leyner pored over medical textbooks and studies to find out that some people have a strange reaction to blazing sunlight that brings on an uncontrollable sneezing fit. This is due to something called the photic sneeze reflex--also known as autosomal dominant compelling helio-ophthalmic outburst, or ACHOO. A 2005 study of six Spanish families showed that there are usually two to three "achoo"s per episode of ACHOO. This reflex is relatively under-studied and not completely understood, says Goldberg, but it is thought to have something to do with an accidental crossing of nerve signals.
"Why does it feel so hot outside when it is 90 degrees if our body temperature is 98.6?"
This question comes up all the time, says Goldberg (most likely during the sweltering East Coast summers). The answer is found in the human body's way of regulating temperature. We're constantly producing heat as we burn calories and exert energy, says Goldberg, and the heat needs to escape. He explains that it's easier to release pent-up heat when the temperatures outside are moderate or cool. When the temps soar, the body increases blood flow to the skin to help the heat escape through sweat. The hotter it gets, the more sweat and energy the body needs to exert, and the harder it ends up working. As a result, you feel like you're burning up.
"If you're stranded on a desert island, should you drink ocean water or, um, your own 'water?'"
This is definitely one of the more far-fetched questions Goldberg has been asked in his 20-plus years as an emergency room doctor and assistant professor of emergency medicine at New York University. But the answer underscores the importance of staying hydrated at all times. Our drink of choice would have been seawater. But Goldberg informs us that we have it wrong: Seawater is three times as concentrated as human blood, and to process it, the body would need to excrete the excess salt through the kidneys as urine. As your body worked to flush out the salt, you'd lose precious fluids, and become even more dehydrated. Before long, your muscles would atrophy, your heart would pound out of rhythm, and you'd eventually die of dehydration. He says it's probably safer to drink urine than seawater, but you'd likely be too dehydrated to make enough to quench your thirst.
"Can pins and needles in your feet cause you to become paralyzed?"
Goldberg says he's seen many people end up in the ER because they've failed to respond to that weird prickly feeling, perhaps because they've been knocked out by alcohol, sleeping pills or a punch in the face. He explains that when you've been kneeling for too long (or doing something else that puts pressure on your leg), the arteries in that area can become compressed, preventing them from providing tissues and nerves with oxygen and glucose. This also blocks nerve pathways, causing some nerves to stop firing and others to go off like a 4th of July fireworks finale. When the brain receives these signals, it interprets them as that uncomfortable sensation of pins and needles. Prolonged pressure on the arteries can indeed lead to temporary or even permanent nerve damage, so it's important to respond to the feeling as soon as you notice it.