WonderQuest:  On the web since 1997...      

Swallowing wrong, Feisty lemmings, Fahrenheit's 180 degrees

Q: What happens to food that goes down the wrong way when we swallow? --Lanney A, Sandia Park, New Mexico

[National Health Institutes] The swallowing reflex passes the food through the pharynx (the canal that connects the mouth with the esophagus). During this stage, the larynx (voice box) closes tightly and breathing stops to prevent food or liquid from entering the lungs.

A: It can go down the windpipe and end up in the lungs but probably not. Instead, we cough it out.

We swallow to get food from the mouth through the throat to the stomach without letting it come out the nose or down the windpipe. Various flaps and muscles work together to pull off this feat: five or six major nerves and 23 muscles. But the flaps work automatically and we barely notice. We swallow during a meal and throughout the day and night to clear saliva from our mouths: 2,400 times a day. But now and then something goes wrong.

When we have food or drink in our mouth and we're breathing, the food can go down the windpipe. We cough as our first line of defense. Almost always, we blow the foreign body out. Otherwise, it can slip down the windpipe. The second line of defense--mucous membranes--battles the stray particle in the trachea. Tiny flailing hair-like structures called cilia push the mucus containing the foreign object back and out. If this fails, the last defense line takes over in the air sacs of the lung: white blood cell macrophages surround the particle and wash it away through the bloodstream.

" The macrophages can clear only very small microscopic particles such as bacteria," says Gail Sullivan, assistant professor at the University of Virginia Health Science Center.

If all fails, bacteria from the food speck can infect the lung.

Q: Do lemmings commit suicide? --Jack W., McLean, Virginia

A: Mass suicides? No, but nobody knows why lemming numbers fluctuate so. What's more it isn't a local phenomenon. The numbers are high or low frequently over a large Arctic area at the same time.

Perhaps lemmings weed out their weak. When the population nosedives, the numbers hover scarily close to zero. It approaches species extinction. Yet the strongest lemmings--those most able to adapt to fast-changing conditions in the Arctic--survive and the species continues.

We've investigated many theories. None fit yet.

• Predators overeat lemmings? No, instead, lemmings control predator population. Animals that eat lemmings decline when lemmings vanish and increase when lemming populations baloon.
• Epidemic diseases sweep through lemmings? Nope, virtually no disease occurs during some declines.
• Low food supply and some starve? Food does vary but nobody has been able to show a cause and effect.

Lemmings are aggressive little creatures that fight together as their numbers increase. Overcrowding stress may change hormone levels, which can decrease birth rates. Also, with enough population stress, they kill each other. But they don't commit suicide by dashing into the sea.

The suicide misconception started in the mountains of Norway. Lemmings do get restless when their numbers are high and some wander downhill, which leads them to the sea or a lake. A few stray onto floating ice or jump in the water but there is no authentic account of mass suicides or of migrations moving in a given direction.

Further Surfing:

Canadian Wildlife Service: lemmings

Q: Why in the world did Fahrenheit develop such an awkward thermometer: 32 degrees for the water freezing point and 212 degrees for its boiling point?

A: It's true that the Celsius system beats Fahrenheit's for simplicity. Zero and 100 are certainly handier than 32 and 212.

Here's a key clue: there are 180 degrees between 212 and 32. Daniel Gabriel Fahrenheit made instruments in Amsterdam and liked 180 degrees. It's half the number of degrees in a circle. Moreover, it's a rational number (divisible by such handy integers as 2, 3, 4, and 5)and therefore useful in calculations.

Fahrenheit set the zero of his scale at the temperature ice melts when it's mixed 50-50 with salt: for practical reasons. This is a stable mixture whose temperature he could measure. Then he assigned the value of 30 degrees to the temperature at which pure ice melts. He measured the body temperature as 96 degrees and later the temperature of boiling water as 212 degrees. Oh, oh: he noticed that there are 182 degrees, not his desired 180, between 212 and 30. Fahrenheit arbitrarily changed the value for pure water's freezing point from 30 to 32 degrees. Now the difference between water's boiling and freezing point on Fahrenheit's scale was the value he wanted--180 degrees.

Fahrenheit invented his thermometer scale in 1709, thirty-three years before the Swedish astronomer, Anders Celsius, came up with his.

(Answered Nov. 8, 2002)