Medical Mind Bogglers
Medicine and science have made great strides over the past 100 or so years. While experts focus on major problems, answers to everyday or common scenarios are often more elusive. For example, why do some people sneeze when they go out into the sun? Or why do the fingers get wrinkly after being submerged in water for a long time?
Sherry Seethaler, Ph.D., Science Writer with the University of California, San Diego, wanted to spark interest in medicine and science. As a weekly column writer, she often received questions by readers looking for answers to odd or strange things about health and the human body. She searched through studies and went directly to the experts to find the answers to those questions. Some of the questions and answers were published in her book, Curious Folks Ask. Here are some of the answers posted in her book:
Why do some people sneeze in response to sunlight?
This phenomenon is called the photic sneeze reflex, also known as the ACHOO (autosomal dominant compelling helio-ophthalmic outburst) Syndrome. Researchers estimate it affects about 25 to 33 percent of Americans. Some people will also sneeze in response to other light sources, such as a bright light in the ceiling or a camera flash. While the exact cause for the response isn’t known, scientists believe it may be triggered by crossed signals in the brain. The nerve responsible for facial sensation (the trigeminal nerve) and the sneezing reflex is located very near the optic nerve (the nerve through which visual information passes to the brain). When the eyes sense a source of bright light, the optic nerve fires a signal to tell the brain to constrict (narrow) the pupil to limit the amount of light entering the eye. That signal may be picked up by the trigeminal nerve and is interpreted as an irritation, triggering the sneeze reflex.
What causes the lump in the throat during emotional distress?
When the body senses some type of negative stress, it instinctively switches into a “fight or flight” mode. The sympathetic nervous system causes the glottis, an area in the throat, to open wider to allow more air to get into the lungs. Normally, the glottis constricts to keep food and liquids out of the lungs. The lump in the throat sensation occurs because the glottis is being told to open and close at the same time, creating a “tug of war” between the two reflexes of the body. Generally, the sensation lasts only a short time.
How can people claim to have “out-of-body” experiences?
Sci-fi enthusiasts may want to believe out-of-body experiences are related to connection with alternate universes. However, Seethaler says, even if those other universes exist, science shows we are unable to perceive them or connect with them. Instead, the phenomenon may have more to do with crossed sensory signals in the brain. Out-of-body experiences have been reported in epilepsy patients undergoing electrical stimulation of the brain.
Why do the fingers and toes get wrinkled after being immersed in water?
The outer layer of skin is made of dead skin cells, which absorb water. The extra moisture causes the cells to swell. The wrinkles develop to accommodate the increased size of the surface area caused by the swollen skin cells. Wrinkling doesn’t occur when the hands or feet are submerged in saltwater because the salt draws moisture out of the skin. Seethaler says constriction of blood vessels also appears to influence wrinkling. When a severed finger is reattached, it doesn’t wrinkle in water. Scientists believe nerve damage from the injury may impair the body’s ability to constrict blood vessels.
Can type 2 diabetes be cured?
This question was asked because a person taking medication for type 2 diabetes can often bring blood sugars back to a normal range by eating a healthier diet, getting more exercise and losing excess weight. In many cases, medications can then be stopped. But does this mean the person is cured of diabetes? Seethaler says the answer is no, because if the patient regains the weight, the diabetes will come back. In this case, the disease is under control, but not eliminated.
Why don’t we get cancer of the heart?
Cancers usually develop in epithelial cells, the cells that form the outer layer of skin and line the digestive tract, airways, urinary tract and reproductive systems. The heart, on the other hand, is a muscle. Cancer occurs when dividing cells mutate. Comparatively, epithelial cells divide at a much faster rate than muscle cells. Thus, there is more of a chance that an epithelial cell than a muscle cell will turn into cancer. Seethaler acknowledges that heart cancer isn’t unheard of. But when it occurs, the cancer is usually the result of a metastasis, or cancer that has spread from another part of the body.
Seethaler’s book contains answers to a lot of other interesting medical phenomena. It also has some answers to basic science questions and background on day-to-day inventions. The book is published by FT Press and retails for $19.99.
Schrock, Karen, “Looking at the Sun Can Trigger a Sneeze,” Scientific American, January 10, 2008, electronic version, http://www.scientificamerican.com.
Seehusen, Dean, M.D., and Sally Weaver, Ph.D., M.D., “Resident Research in Family Medicine,” Family Medicine, October 2009, Vol. 41, No. 9, pp. 663-669.
Seethales, Sherry, Curious Folks Ask, Upper Saddle River: FT Press, 2010.
Wade, N., “Beyond Body Experiences,” Cortex, February 2009, Vol. 45, No. 2, pp. 243-255.
