YOU FRET ABOUT your teeth, hair, lungs, heart; you're hardly aware of my existence. I am your liver. When you think of me at all, you have no trouble visualizing me. I look like what I am supposed to look like - liver. The largest organ in your body, I weigh three pounds. Protected by ribs, I pretty well fill the upper right part of your abdomen.
Despite my unexceptional appearance, I am the virtuoso among your organs. In complexity I shame those headline grabbers, the heart and lungs. I do upward of 500 jobs, and if I fall down on any of the major ones, you had better start making funeral arrangements. I participate in virtually everything that you do. I provide muscle fuel for your golf game, digest your breakfast bacon and manufacture the vitamin that helps your night vision.
A big chemical company would have to build acres of plant to do my simpler jobs. The harder ones it couldn't do at all. I produce over 1000 different enzymes to handle my chemical conversions. You cut your finger and might well bleed to death but for the clotting factors that I manufacture. I make antibodies that protect you from disease. The protein fragments (amino acids) made in the intestine from that steak you love so much could be deadly as cyanide if they ever got into your bloodstream. I "humanize" them - change them from amino acids to human protein. And if there is any surplus that your body doesn't need, I change it into urea and pass it along to the kidneys for excretion.
Your adrenal glands produce enough salt-saving hormones to make you terribly swollen - but I destroy the excess. I even act as a kind of safety valve for the heart. On my upper side, the hepatic vein goes directly to your heart. If a surge of blood comes along that might smother heart action, I swell, soaking blood up like the vascular sponge that I am. Then I feed it out gradually so the heart can handle it.
I am the great detoxifier. Shoot some poisons - such as the nicotine, caffeine and various drugs that you, absorb daily - into my exit vessels, leading to the heart, and you would be dead in minutes. Shoot them into my entrance vessels and the six to ten seconds it takes for blood to pass through me give me ample time to extract their sting.
Even the alcohol in your cocktails - which but for me would accumulate in your blood in lethal quantities - I break down into harmless carbon dioxide and water. I can handle about half a highball or three fourths of a can of beer an hour; you could go on indefinitely at that rate without feeling any effects. But if you indulge at a faster clip - you could leave me with an all-night job.
Some materials produced by the body are, of course, toxic if accumulated in too large amounts. My job is to keep them in check. When you play golf, your muscles are burning glucose and throwing off potentially deadly lactic acid. Instead of discarding it, I convert the lactic acid into glycogen for storage. I'm a very thrifty housekeeper - no waste.
When you eat a chocolate bar, the cane sugar is changed into blood sugar - glucose in the intestine. Let too much of this glucose be fed into the bloodstream and you will go into a coma and die as diabetics might without insulin. I see to it that this doesn't happen. If there is too much glucose in the blood, I convert it into starchy glycogen. I can store the equivalent of half a pound of sugar this way. Then when blood sugar drops between meals - too little can be as bad as too much - I convert the glycogen back to glucose and feed it out.
It is the same with your red blood cells. Each second, ten million of them die and must be disposed of. I salvage the breakdown products, conserving them for use over and over again in building new red cells. And some of the debris I use in making a daily quart of bile, the bitter, green-yellow digestive juice.
Normally, this fluid passes from me to the gallbladder to the little pouch called the, duodenum, between the stomach and small intestine. It is released at mealtime to break down big globules of fat into small water-soluble globules that can be digested. On top of this, bile washes away fat deposits that might otherwise block my channels.
The bile that I dribble continuously into the gallbladder also contains two pigments - waste products from red-cell destruction. One is bilirubin (red bile); the other is biliverdin (green bile). Occasionally these pigments get into the bloodstream in too large a quantity, and produce jaundice - a yellow staining of the skin and eyes. A symptom, not a disease, jaundice simply announces that something is wrong with me.
The trouble is one of three types. Certain diseases - malaria, some types of anemia - destroy red blood cells rapidly, and pigments from the destroyed cells accumulate faster than I can dispose of them. Obstructions in the gallbladder or ducts can also back up pigments and spill them over into the bloodstream to produce jaundice. Or perhaps my working cells may be inflamed by hepatitis or other diseases, or my channels may be blocked by fat and I am unable to excrete the pigments. Then I am in serious trouble.
Still, I have enormous reserve and regenerative capacity. Disease can destroy as many as 85 percent of my working cells and I'll continue to do my jobs. (Actually, this reserve capacity is one of my weak spots, for I can be in really grave condition before you get any warning signs.) As much as 80 percent of me can be cut away, as in cancer surgery, and I'll still function normally. I can also do something that most other organs can't: I can rebuild myself, in a few months, back to normal size.