Dear Peter, as one of your organs of vital importance, I have a couple of words to say to you. I do not make any noise like the heart or stomach. Neither do I produce electric waves like the brain. Therefore you don’t even realize my presence most times. However, I am a central laboratory controlling the chemical mechanisms of your body. All of your blood passes through me and I constantly supervise it. Do not misunderstand me; I am not speaking on my own behalf, since I have neither the knowledge nor the will to build this splendidly working mechanism.

All the organs functioning in your body have a direct or indirect relationship with me. I can be compared to a kind of “chemical brain.” All metabolic activities are among my duties, including the control of excretions, digestion, and the composition of blood. You would be stupefied if I listed every single function I carry out, but let me tell you this much: biochemists have discovered that I am directly included in more than 80 different activities and related to more than 5,000 chemical reactions taking place in your body. Surprised? But this is only what they’ve learned so far; you do not know me in detail yet. My plain appearance is in contrast with my numerous functions. My size is about one-tenth of the body of a six-month-old fetus; now that you have become a young man, I weigh about one fiftieth of your body weight. Since I am the largest excretory organ in your body, I am firmly strapped with mesentery so you can run, jump, and make other movements without trouble.

Most people see me merely as a bile-producing organ, which happens to be among the simplest of my duties. Let me explain it another way: the heat I produce while working is equal to one-third of the heat your body produces while resting. I have a special circulatory system. Since I am located at a “junction,” the blood coming from the intestines which bear nutrient molecules come to my vein first together with the blood from the spleen, before joining the rest of the bloodstream. It can be compared to an obligatory customs check. The amount of blood I supervise within 24 hours is about 2,000 liters. With every heartbeat, almost 28 percent of the blood being pumped passes through me.

I adjust the level of blood sugar in a very sensitive balance. If you eat desserts or pastries I convert excess sugar into glycogen (animal starch) and store it. If your blood sugar decreases from hunger, I break down glycogen into sugar (glucose) and come to your help so that you do not come to a halt, like a car out of fuel.

I use various protein molecules to synthesize numerous enzymes. I also play a role in blood coagulation, red blood cell production, and storing the iron you need. You know, nothing is wasted in the divine system of nature. So how can I waste anything? When the aged red blood cells die, I help the spleen to break them down and store the iron they contain. My job in fat metabolism is no less important. Thanks to the bile I produce, the fatty food you eat is broken down to smaller molecules to be absorbed in a way similar to detergents remove oily remnants from dishes. Naturally, the fat-soluble vitamins (A, D, E, K) are also absorbed along the process. I store the excess of both these vitamins and fats. Fats are an important fuel particularly for your heart muscles. I excrete an average of 600–700 grams of bile a day. Two minutes after oily foods pass to duodenum the walls of my gallbladder are operated. Through contractions of 2–6 times a minute and a pressure of 25–30 mmHg, the bile is passed to duodenum in a time span of 15 to 90 minutes. What gives bile its yellowish-green color is the substance named bilirubin, which appears with the breaking down of the old red blood cells and disposed of through the bowels.

The Kuppffer cells—as you name them—have the duty of checking out newly produced blood cells one by one in addition to producing antibodies against germs. If any ill-formed blood cells come up, I must detect and destroy them. Otherwise they corrupt your blood. Thanks to the Kuppffer cells, the ill-formed blood cells are destroyed as soon as they are detected.

The average longevity of my cells varies between 150-180 days (220 days maximum). New cells are produced immediately to replace the dying ones and the system works smoothly. In each of these cells there are 1,000-3,000 mitochondria and millions of ribosome. An average of 180 new ribosome are produced every second. Although none of my cells have consciousness or intelligence, thousands of them come together to form little lobes resembling hexagons. The number of these lobes varies between 50,000 to 100,000.

Dear Peter, you intake various toxic substances together with the foods you eat. You don’t even realize that food has been corrupted by bacteria and fungi until its taste changes. Frankly, you should not have lived very long with so much toxic intake; Providence has given me an important duty to protect you from such harm. I capture these toxic compounds released into your bloodstream and neutralize them. The same goes for different medicines you take; I try to neutralize their toxic effects as well. But I have my own limits of tolerance; if I am faced with more toxic substances than I can handle, then I give signals of danger. You wonder how. Well, I shout “help” through red spots in your hands and itchy spots on your skin. You should be more careful about what goes down your throat.

Given that I fulfill various important functions, the littlest failure in me reveals itself as a health problem immediately. Hepatitis is among the common diseases heralding my failure. Excessive increase of bilirubin in your blood causes the white of your eye and your skin to turn yellow. I fear viruses most. Particularly hepatitis B and C viruses destroy my tissue. And alcohol, as you know, is my sworn enemy. I have to exert myself to neutralize even a tiny amount of alcohol. And if the hepatitis virus is added, I become knocked down and contract cirrhosis. It does not happen suddenly, though. Along the process which you know as liver failure I give various signals: skin eruption, digestion problems, sleepiness, and headache after meals, and so on. Since these symptoms are not serious problems, most people ignore these signals I give. Due to my various functions, the lab tests about me are more than a hundred.

Talking about my enemies may have upset you a bit, but it’s not all doom and gloom. After all, I am the organ with the highest capacity to renew itself. Sounds good, right? Otherwise I would have been finished off long ago, so this ability is a real blessing. Let me give you an example: although 90 percent of my cells are destroyed during hepatitis, I can help you survive with the remaining 10 percent if you rest well and control what you eat. If you ignore the disease, it might lead you and me to the grave. Do not ever believe those who take this lightly and say: “This doctor says that a small amount of alcohol is good for health.” Tell it to the marines. Those who say that should visit hospitals first. I’m sorry, Peter, but it really gets on my nerves. If they could only appreciate a work of art like me. Anyway, that’s all for now, please take good care of me.