I AM ABOUT the size and shape of a large dog's tongue - six inches long, gray-pink in color, weight about three ounces. I reside deep in your abdomen (behind the stomach and in front of the spine) in an overcrowded tenement of assorted organs that include the liver, kidneys and large intestine. Since you have eaten calves sweetbread, you know my consistency. I am your sweetbread - your pancreas.
I am a very busy organ. Without the enzymes I produce, you could consume mountains of food and still he malnourished. Every time you bat an eyelid, every time your heart takes a pumping stroke, cells must provide energy. I help supply the fuel to stoke the cellular fires.
Actually, I'm two glands wrapped into one package, and I produce two important hormones that empty into your bloodstream. My glucose, or blood sugar, is the fuel for cells, the chief provider of energy; my insulin keeps blood sugar at proper levels and sees that it is burned properly - a very critical and delicate task, I may add.
For my key role in digestion, I produce about two pints of digestive juices a day. Not bad: 32 ounces of fluid from a three-ounce gland! When your food leaves the stomach it is a highly acid gruel, or chyme. (You fret occasionally about "acid stomach," but the acid has its job to do in starting the breakdown of proteins.) This acid could spell disaster farther along your digestive tract - eating away the delicate lining of the small intestine - so I must produce enough alkaline juice to neutralize it.
When you sit down to the dinner table, my tens of thousands of little saclike acini get a signal from the nervous system to start manufacturing alkaline juices. But I don't go into high gear until the chyme actually starts coming through the pylorus, the gateway from the stomach to the duodenum - that pouchy first ten inches of your small intestine. As a matter of self protection, the duodenum starts manufacturing the hormone secretin, whose chemical message via the blood prods me into peak alkalinizer production.
Actually, neutralizing acid is not a very impressive chemical feat. Some of my other tasks are far more formidable. If most of the foods you eats for instance, ever reached your bloodstream in the form in which they are consumed, you would he a very dead duck in no time at all. But they don't, because I play the major role in rendering them acceptable.
For this task, I produce three talented enzymes. One of these chemical virtuosos, trypsin, initiates the breakdown of protein into amino acids, which the bloodstream can pass around the body for tissue building. Another enzyme, amylase, converts starch into sugar. A third, lipase, attacks fat globules, breaking them into fatty acids and glycerin. Whether you eat a gourmet dinner or a hot dog, the results are pretty much the same: the end products are almost always totally unlike the foods you forked into your mouth.
Fortunately, I have a comfortable excess productive capacity for my digestive juices. Half of my acini could do the job. You could even survive if my total production were destroyed. Saliva, gastric and intestinal secretions would do a job of sorts. But digestion would he a misery.