Another risk that many people aren’t fully aware of is hepatitis C. According to the Centers for Disease Control and Prevention, about one in thirty people in America born between 1945 and 1965—that’s two million people altogether—will have hepatitis C without knowing it. (People born in that period were at greater risk in large part because of contaminated blood transfusions and the sharing of needles by people doing drugs.) Hepatitis C can live within victims for forty years or more, stealthily demolishing their livers, without their being aware of it. The CDC estimates that if all those people could be identified and treated, 120,000 lives would be saved in America alone.
The liver was long thought to be the seat of courage, which is why a cowardly person was deemed “lily-livered.” It was also considered the source of two of the four humors—black bile and yellow bile—respectively responsible for melancholy and choler, and thus was considered responsible for both sadness and anger. (The other two humors were blood and phlegm.) The humors were believed to be fluids that circulated within the body and kept everything in balance. For two thousand years, a belief in humors was used to explain people’s health, looks, tastes, disposition—everything. In this context, humor has nothing to do with amusement. It comes from a Latin word for “moisture.” When we talk today of humoring someone or of people being ill-humored, we are not talking about their capacity for laughter, at least not etymologically.
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Packed in beside the liver are two other organs, the pancreas and spleen, which are often paired up because they live side by side and are similarly sized, but actually are quite unalike. The pancreas is a gland and the spleen is not. The pancreas is essential to life; the spleen is expendable. The pancreas is a jellylike organ, about six inches long, shaped roughly like a banana (and about the same size), tucked behind the stomach in the upper abdomen. As well as insulin, it produces the hormone glucagon, which is also involved in regulating blood sugar, and the digestive enzymes trypsin, lipase, and amylase, which help digest cholesterol and fats. Altogether every day it produces over a quart of pancreatic juice, a pretty prodigious amount for an organ of its size.
The pancreas of an animal when cooked for consumption is known as a sweetbread (the word is first recorded in English in 1565), but no one has ever worked out why, because there is nothing sweet or bread-like about it. “Pancreas” isn’t recorded in English until late the following decade, so “sweetbread” is actually the older term.
The spleen is roughly the size of your fist, weighs half a pound, and sits fairly high up on the left side of your chest. It does important work monitoring the condition of circulating blood cells and dispatching white blood cells to fight infections. It also acts as a reservoir for blood so that more can be supplied to muscles when suddenly needed, and it aids the immune system. A person who is splenetic is angry or wrathful; we still vent our spleen when angry.
Medical students learn to remember the principal attributes of the spleen by counting upward in odd numbers; 1, 3, 5, 7, 9, 11. That is because the spleen is 1 x 3 x 5 inches in size, weighs 7 ounces, and lies between the 9th and the 11th ribs—though in fact all those numbers but the last two are merely averages.
Just beneath the liver and also closely associated with it is the gallbladder. It is a curious organ in that many animals have gallbladders and many do not. Giraffes, oddly, sometimes have gallbladders and sometimes don’t. In humans, the gallbladder stores bile from the liver and passes it on to the intestines. (“Gall” is an old word for “bile.”) The chemistry can go wrong for a variety of reasons, resulting in gallstones. Gallstones are a common complaint and were traditionally said to be most often found among women who were “fat, fair, fertile, and forty,” according to a well-known but, I’m told, highly inaccurate mnemonic among doctors. As many as a quarter of adults have gallstones, but usually don’t know it. Just occasionally a gallstone will block the bladder outlet, leading to abdominal pain.
Surgery for gallstones (which are formally called calculi) is now routine, but once it was often a life-threatening condition. Until late in the nineteenth century, surgeons dared not cut into the upper abdomen because of the dangers of delving amid all the vital organs and arteries up there. One of the very first to attempt an operation on a gallbladder was the great but odd American surgeon William Stewart Halsted (whose extraordinary story we will cover more fully in chapter 21). In 1882, while still a young doctor, Halsted conducted one of the first surgical removals of a gallbladder, on his own mother, on a kitchen table in their family home in upstate New York. What made this all the more remarkable was that there was no certainty at this time that someone could survive without a gallbladder. Whether Mrs. Halsted was quite aware of this as her son pressed a handkerchief of chloroform to her face is not recorded. At all events, she made a full recovery. (In an unfortunate irony, the pioneer Halsted would die following gallbladder surgery on himself forty years later, by which time such surgery had become commonplace.)
Halsted’s operation on his mother recalled a procedure undertaken a few years earlier by a German surgeon, Gustav Simon, who removed a diseased kidney from a female patient without having any certain idea what would happen and was delighted to discover—as presumably was the patient—that it didn’t kill her. It was the first anyone realized that humans can survive with just one kidney. It remains something of a mystery even now as to why we have two kidneys. It is splendid to have a backup, of course, but we don’t get two hearts or livers or brains, so why we have a surplus kidney is a happy imponderable.
The kidneys are invariably called the workhorses of the body. Each day they process about 190 quarts of water—that is the amount a bath holds up to the overflow level—and 3.3 pounds of salt. They are startlingly small for the amount of work they do, weighing just five ounces each. They are not in the small of the back, as everyone thinks, but higher up, about at the bottom of the rib cage. The right kidney is always lower because it is pressed down upon by the asymmetrical liver. Filtering wastes is their principal function, but they also regulate blood chemistry, help maintain blood pressure, metabolize vitamin D, and maintain the vital balance between salt and water levels within the body. Eat too much salt and your kidneys filter out the excess from your blood and send it to the bladder so that you can pee it all away. Eat too little and the kidneys take it back from the urine before it leaves your body. The problem is that if you ask the kidneys to do too much filtering over too long a period, they get tired and stop functioning terribly well. As the kidneys become less efficient, the sodium levels in your blood creep up, pushing your blood pressure dangerously high.
More than most other organs, the kidneys lose function as you age. Between the ages of forty and seventy, their filtration capacity drops by about 50 percent. Kidney stones become more common, as do more life-threatening illnesses. The death rate from chronic kidney disease has jumped by more than 70 percent since 1990 in the United States and by even more in some third world countries. Diabetes is the commonest cause of kidney failure, with obesity and high blood pressure as important contributory factors.