What Weighs More, the Sunday Paper or Your Head?

We’re constantly stumbling upon fascinating “human body” facts, like “the surface area of our small intestine, laid flat, would cover a football field” or “there are 60,000 miles worth of blood vessels in the human body.” How, we ask, do people know these things?

Fun though it is to imagine, it’s unlikely that some compulsive human anatomist actually measured every blood vessel with a tape measure after one heck of a dissection or went half-barmy trying to squash 20 feet of human entrails totally flat. But then how? We made a few calls to find out.

We haven’t yet ascertained how it’s known that the nose and sinuses secrete two quarts of mucus daily. (A local nose surgeon, Dr. Robert Kotler, tells us that when he was in med school, 27 years ago, it was one quart; noses must be working overtime these days.)

The main thing we’ve learned is that it’s hard to track these superlatives down. Take our experience with the lung--whose surface area, don’t you know, would cover a tennis court if laid flat.

We called the American Lung Assn. of California and enlisted the help of spokesman Andy Weisser (pronounced “wiser,” not “wheezer”). Five of his colleagues confirmed the tennis court number. None knew how the measurement was made, but one cheerily volunteered that people breathe 30 pounds of air a day--which is equivalent to 3,500 gallons--and found reference to the tennis court fact in a 1986 educational pamphlet by lung expert Dr. John Luce of UC San Francisco.

We called Luce and posed our question. He burst out laughing.

“You find it everywhere--I’ve read it twice this week. I don’t have a clue where it comes from,” he said. “I’ve always wondered whether it includes just the playing surface or the backstop as well.”

Luce, who, like many docs, learned this fact in med school, sent us to his colleague Dr. John F. Murray.

To do the calculation, explains Murray, first you inflate a lung (lungs collapse when people die). Then you cut it up and examine the slices under the microscope. This lets you figure out how much of each sample is tissue, and how much air spaces. From there, getting the surface area is a simple matter of mathematical calculation, taking into account the size of a lung, which depends on the size of the person.

The most careful measurements Murray knows of would give his two lungs a surface area of 110 square meters.

“I’ve never found out what the size of a tennis court is--but I’ll tell you, the tennis courts I play on are a heck of a lot bigger than 10 by 11 meters,” he said.

He’s right. A singles tennis court measures 78 feet by 27 feet, or 195.7 square meters. The lungs’ surface area would cover half a tennis court.

Thumbs Up to Jabbing the Ear Instead

Meanwhile, have you ever wondered why, when a small blood sample is needed (to test blood glucose, for instance), it’s the thumb that we jab? Dr. Simon Carley did.

“I just thought it odd that we chose one of the most sensitive sites on the human body for sampling,” he said.

Thus Carley, a specialist registrar in emergency medicine in the Manchester Royal Infirmary in England, decided--along with his colleagues--to compare thumb-jabbing with earlobe-jabbing in 60 consenting patients to see which of the two was less painful. They used a special “pain scale” to ascertain the level of pain patients felt when they were jabbed.

The result, published in the July 1 British Medical Journal: Puncturing the earlobe is less painful than puncturing the fleshy part of the thumb, for reasons unclear (perhaps there are fewer pain-sensing nerves at that site). Anyway, Carley and company suggest that samples should be taken from the ear instead of thumb.

The only problem we see is with getting bandages stuck in the hair. Or mistakenly trying to thread an earring through the puncture wound.