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ornithopter: I Am Joe's Liver |
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Unprepossessing but potent, this largest of the body's vital organs is a veritable jack-of-all-trades.
I Am Joe's Liver
By J.D. Ratcliff
Joe frets about his teeth, hair, lungs, heart; he is hardly aware of my existence. I am Joe's liver.* When he thinks of me at all, he has no trouble visualizing me. I look like what I am supposed to look like-liver. The largest organ in his body, I weigh three pounds. Protected by ribs, I pretty well fill the upper right part of Joe's abdomen.
Despite my unexceptional appearance, I am the virtuoso among Joe's organs. In complexity I shame those headline grabber, the heart and lungs. I do upward of 500 jobs, and if I fall down on any of the major ones, Joe had better start making funeral arrangements. I participate in virtually everything that Joe does. I provide muscle fuel for his golf game, digest his breakfast bacon and manufacture the vitamin that helps his 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. Hoe cuts his finger and might as well bleed to death but for the clotting factors that I manufacture. I make antibodies that protect him from disease. The protein fragments (amino acids) made in the intestine from that steak he loves so much could be deadly as cyanide if they ever got in his bloodstream. I "humanize" them-change them from amino acids to human protein. And if there is any surplus that his body doesn't need, I change it into urea and pass it along to the kidneys for excretion.
Joe's adrenal glands produce enough salt-saving hormones to make him 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 Joe's 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 Joe absorbs daily-into my exit vessels, leading to the heart, and Joe 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 Joe's cocktails-which but for me would accumulate in his 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; Joe could go on indefinitely at that rate without feeling any effects. But Joe tends to imbibe at a faster clip-which can 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 Joe plays golf, His 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 Joe eats 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 Joe will go into a coma and die-as diabetics might without insulin. I see to it that his 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 Joe's 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 gall bladder to the little pouch called the duodenum, between stomach and small intestine. It is released at mea time 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 tha I dribble continuously into the gall bladder 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 quantity, and produce jaundice-a yellow straining of the skin and eyes. A symptom, not a disease, jaundice simple announces that something is wrong with me.
The trouble is one of three types. Certain dieases-malaria, some types of anemia-destroy red blod cells rapidly, and pigments from the destroyed cells accumulate faster than I can dispose of them. Obstructions in the gall bladder or ducts can also back up pigments and spill them over into the blood stream 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 pigment. 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 Joe gets 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': I can rebuild myself, in a few months, back to normal size.
Hepatitis can knock out millions of my working cells. But in a few weeks this virus infection usually subsides, and I repair the damage. In most cases, I return to normal.
Infiltration of fat may be quite serious, because the fat displaces functioning cells. If there is enough of it, I become distended, sensitive. The fat can even rupture into the bloodstream and produce vessel obstruction in vital organs. Moreover, fat infiltration is apt to precede another serious problem: replacement by non-functioning, fibrous tissue. I become shrunken, hard, knobby, a sickly yellowish color. This is cirrhosis-likely to be very bad news indeed.
What causes cirrhosis? A lot of things. It can follow infection or poisoning with arsenic or other drugs. But the two things that seem to play the biggest role are poor diet and alcohol. The man who eats lightly, and consistently consumes 12 ounces or more of whiskey a day, is almost certain to develop a fatty liver, and to go on from there to cirrhosis. Fortunately, Joe doesn't fall into this class. There are a few wound stripes on me, but I have ample functioning cells left.
I've been called a "silent" organ, yet in times of trouble I have ways of complaining. If Joe notices undue fatigue, loss of appetite, weakness, bloating in the abdominal region, he'd better begin thinking of me. If he notices dilated, spider-shaped blood vessels on the upper part of his body, or if he becomes jaundiced, he'd better get to a doctor fast. To Be sure that it is me causing the trouble, the doctor has some pretty clever tests. In one, a dye (bromsulfalein) is injected. If I'm in top form, I should get rid of 95 percent of the dose in 45 minutes. In another widely used test, the pigment bilirubin in the blood is measure. If there is too much, I'm likely to be having difficulties. But the most definitive test is to push a hollow biopsy needle into me and pull out a core of my tissue for study.
So far, at least, Joe has had no need for may of this. But even if I should develop cirrhosis, the doctors have learned a lot about handling this, my most common serious problem. They would put Joe to bed and feed him a nutritious diet, high in protein. He would get liberal doses of vitamins and a warning not even to look at alcohol. Under this treatment, I'd have a good change of getting a new start.
What can Joe do to see that none of this unpleasantness happens? He can watch his weight; when he gets fat, I get fat, too. Vitamins, particularly the B vitamins, may help. But low alcoholic intake and a sensible diet are the best bets. Given a minimum of care, I'll go along being the silent jack-of-all-trades that does so much to keep Joe in business.
*Joe, 47, is a prosperous businessman. Some of his other organs have told their stories in The Reader's Digest: "I Am Joe's Heart," April '67; "I Am Joe's Stomach," May '68; "I Am Joe's Lung," March '68.
This article is based largely on interviews with Dr. William D. Davis, Jr., head of the department of internal medicine and gastroenterology at New Orleans' Ochsner Clinic and professor of clinical medicine at Tulane University Medical School.
Ratcliff, J.D. "I Am Joe's Liver." Reader's Digest. 95. 569. (1969): 81-84.
September 1969
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