Read CHAPTER XVII of A Handbook of Health , free online book, by Woods Hutchinson, on


The Wastes of the Body. Almost everything that the body does in the process of living means the breaking down, or burning, of food; and produces, like every other kind of burning, two kinds of waste-“smoke” and “ashes.”

The carbon dioxid “smoke,” as we have already learned, is carried in the blood to the lungs, where it passes off in the breath. The solid part of our body waste, or the “ashes,” is of two kinds-that which can be melted in water, or is, as we say, soluble; and that which cannot be melted in water, or is insoluble. The insoluble part of our solid body waste goes into the feces and is thus disposed of.

The soluble part of the body waste goes by a somewhat more roundabout route. With the carbon dioxid it is poured by the body cells into the veins, carried to the heart, and pumped through the lungs, where the carbon dioxid is thrown off. Going back to the heart it is pumped all over the body, part of it going through a very large artery to the liver, part through two large arteries to the kidneys, part to the skin, and the rest all over the remainder of the body.

The blood goes completely round the body-circuit from the heart to the fingers and toes, and back again to the heart, in less than forty-five seconds. Practically every drop of blood in the body will be pumped through the liver, the kidneys, and the skin, about once every half minute, so that they get plenty of chance to purify it thoroughly when they are working properly.

This sounds rather complicated; but is interesting, because it shows how much of a “mind of their own” the different organs and stuffs in our bodies have, or what, in scientific language, we call “power of selection.” The skin glands pick out of the blood those waste substances which they are able to get rid of. The kidneys pick out another class of waste substances, which they are best able to deal with; while the liver which is the most important of all, attacks almost every kind of waste brought to it by the blood, and prepares it for disposal by the intestines, skin, and kidneys.

The Liver. The liver has a size to match its importance. It is the largest and heaviest gland, or organ, in the body, and weighs about three pounds, a little more than the brain. It buds off from the food tube just below the stomach, so that its waste tube, the bile duct-about the size of a goose quill-opens into the upper part of the intestine.

The main work of the liver is to receive the blood from all over the body and to act upon its waste substances, burning them up so that they can be taken up, and got rid of, by the glands of the skin and the kidneys. In the process it very frequently changes these waste substances from poisonous into harmless forms; and even when disease germs get into the body and infect it, the poisons, or toxins, which they pour into the blood are carried to the liver and there usually burned up, or turned into harmless substances.

The liver is, therefore, to be regarded as a great poison filter for the entire body. So long as it can deal with the poisons as fast as they are formed, either by the body itself, or in the food, or by disease germs, the body is safe and will remain healthy. But if the poisons come faster than the liver can deal with them, as, for instance, when we have eaten tainted meat or spoiled fruit, or have drunk alcohol, they begin to poison our nerves and muscles, and we become, as we say, “bilious.” Our head aches, our tongue becomes coated, we have a bad taste in the mouth, we lose our appetite and feel stupid, dull, and feverish.

Such waste materials as the liver cannot burn down so that the kidneys and skin can handle them, it pours out through its duct into the intestine as the bile. The bile is a yellowish-brown fluid, which assists the pancreatic juice in the digestion of the food, and helps to dissolve the fats eaten, but is chiefly a waste product. It turns green when it has been acted upon by acids, or exposed to the air. So that the bile which you throw up when you are very sick at your stomach, is green because it has been acted upon by your gastric juice.

As you will remember, the blood which comes from the stomach and bowels is carried by the portal vein to the liver first and, through that, to the heart, instead of going directly to the heart, as all the other impure blood in the body does. This is owing, in part, to the fact that this blood, being full of substances freshly taken or made from the food, is very likely to contain poisons; indeed, as a matter of fact, blood taken from these veins on its way to the liver, and injected directly into the blood vessels of an animal, acts like a mild poison.

In part, however, this blood goes first to the liver, because the liver, besides being a great blood purifier, is a “blood-maker” in the sense that it changes raw food-stuffs in the blood from the intestines into forms which are more suitable for use by the brain, the muscles, and the other tissues of the body. Some of the sugars, for instance, the liver turns into a kind of animal starch (glycogen), which it stores away in its own cells. It also turns both sugars and proteins in the portal blood into fat, part of which it pours into the blood, and part of which it stores away also in its own cells. Thus the liver owes its great size partly to the large amount of blood-purifying, filtering, and poison-destroying work which it has to do, and partly to its acting as a storehouse of starch and fat, which the body can readily draw upon as it needs them.

As all poisons formed in, or entering, the body are brought to the liver for destruction, it is in an extremely exposed position, and very liable to break down under the attack of these poisons, whether of infectious diseases, or chloroform, or alcohol, or those formed by putrefaction in the stomach and intestines. This is why those who have lived long in the tropics and suffered from malaria, dysentery, and other infectious diseases, and those who drink too much alcohol, or have chronic indigestion, or dyspepsia, are likely to have swollen and inflamed livers.

The Gall Bladder. The liver has on its under side a little pear-shaped pouch called the gall bladder, in which the bile is stored before it is poured into the bowel. If this becomes inflamed by disease germs, or their poisons, in the blood, little hard masses will form inside it, usually about the size of a grain of corn, known as gall stones. So long as they stay in the gall bladder, they give little trouble, but if they start to pass out through the narrow bile duct into the intestine, they cause severe attacks of pain, known as “gall-stone colic,” and, by blocking up the duct, may dam up the flow of the bile, force it back into the blood again, and stain all our tissues, including our skin and our eyes, yellow; and then we say we are jaundiced. Jaundice may also be caused by colds or other mild infections which attack the liver and bile ducts and clog the proper flow of the bile.

The Kidneys. The kidneys are another form of blood-filter, which deal chiefly with waste stuffs in the blood left from the proteins, or Meats, of our food-meat, fish, milk, cheese, bread, peas, beans, etc. These waste-stuffs, called urea and urates, are formed in the liver and brought in the blood to the kidneys. These lie on either side of the backbone, opposite the small of the back, their lower ends being level with the highest point of the hip-bones, nearly six inches higher than they are usually supposed to be. When you think you have a “pain across the kidneys,” it is usually a pain in the muscles of the back much lower down, and has nothing to do with the kidneys at all.

A very large artery carries the blood from the aorta to each side of the kidney, and a large vein carries the purified blood back to the vena cava and heart. Two smaller tubes about the size of a crow quill, the waste pipes of the kidneys (the uréters), carry the water containing urea and other waste substances strained out by the kidneys and called urine, down into a large pouch, the bladder, to be stored there until it can be got rid of.

K, kidneys; U, uréters; B, bladder; A, artery; V, vein.]

The kidneys then are big filter-glands. They, like the lungs, are made up of a mesh, or network, of thousands of tiny tubes of two kinds, one set of tubes being blood vessels, and the other set the tiny branches of the kidney tubes which finally run together to form the uréters. The urine filters through from the spongy mesh of blood tubes (capillaries) into the kidney tubes and is poured out through the uréters. It is very important that the urine should be discharged as fast as it fills the bladder, that is, about once every three hours during the day. Nothing should be allowed to interfere with this; and whenever nature tells you that the bladder is full, it should be emptied promptly, or the poisons which nature is trying to get rid of in the urine may get back into the blood and cause serious trouble.

Diseases of the Kidneys. Naturally, the kidneys, working all the time and pouring out, as they do every day, from three to four pints of the liquid waste called urine, are subject to numerous diseases and disturbances. One of the common causes of these is failure to keep the skin thoroughly clean and healthy, as perspiration is of somewhat the same character as the urine; and if it be checked, it throws an extra amount of work upon the kidneys.

Another most important thing to keep the kidneys working well is to drink plenty of water, at least six or eight glasses a day, as well as to eat plenty of fresh green vegetables and fresh fruits, which, as we have seen, are eighty per cent water. Remember, we are a walking aquarium, and all our cells must be kept flooded with and soaked in water in order to be healthy. If the blood becomes overloaded with poisons, so much work may be thrown upon the kidneys that they will become inflamed and diseased and cannot form the urine properly; and then poisons accumulate in the system and finally produce serious illness and even death.

It was at one time believed that eating too much of certain kinds of foods, particularly those that leave much nitrogenous waste in the body, such as meat and fish, could produce a diseased condition of the kidneys, known as Bright’s Disease; but we have found that the larger part of such cases are due to the attack of the germs of infectious diseases, particularly scarlet and typhoid fevers, tuberculosis, and colds. The popular impression that colds from wet feet or long drives in winter may “settle in the kidneys” is wrong, except in so far as those colds are caused by infectious germs.

Another cause of disturbance and permanent damage to the kidneys is the habitual use of alcohol. Even though this may be taken in only moderate amounts, the constant soaking of the tissues with even small amounts of alcohol may be most harmful to the kidneys, as well as to the liver.