Everyday Mysteries
We know what hiccups are: rhythmic, uncontrollable contractions of the diaphragm, the large muscle that separates the chest from the abdominal cavity.
Chronic hiccups, lasting from days to years, can actually be a debilitating condition--even (rarely) fatal. Doctors treat them with tranquilizers and muscle relaxants, numbing of the throat, hypnosis, and, occasionally, surgery to sever one or both of the phrenic nerves, which carry motor impulses to the diaphragm. For less serious cases, there are, of course, hundreds of home remedies of varying utility. Some scientific evidence backs up bag breathing, sipping water without pausing for a breath, and other approaches that have the effect of elevating carbon dioxide in the blood. That appears to decrease the sensitivity of nerves in the brain that trigger the diaphragm.
The best explanation for why people hiccup at all is that hiccups seem to be just a vestige of fetal growth. The hiccup serves a useful purpose before we're born, as part of our prenatal exercise regimen. In the womb's liquid environment, the diaphragm flexes, in order to grow stronger. Meanwhile, the epiglottis closes, to prevent water from getting into the lungs.
Once we start breathing air, however, there is no apparent benefit to hiccups. We simply don't grow out of them. There is no question that the hiccup's more socially unacceptable cousin, the burp, aids in digestion. We hang on to it for good reason. But the hiccup, science seems to think, just is.
The acoustics of quality No musical instrument produces a pure tone. Accompanying each note is a series of overtones--which are what make a violin sound like a violin and a flute like a flute. Overtones are multiples of the basic pitch frequency; the number of overtones and their relative loudness determine a sound's quality.
Involuntary contractions How a hiccup happens 1. To keep food from entering the lungs, the epiglottis normally shuts when you swallow 2. In a hiccup, first the diaphragm suddenly contracts as if to draw air into the lungs, then the epiglottis shuts, interrupting the breath. [Illustration labels]: Epiglottis; Esophagus; Windpipe; Lungs; Diaphragm
advertisement
