HOW THE BODY RIDS ITSELF OF WASTES
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Written by tony benjamin
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Sunday, 02 March 2008 |
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Systems for waste disposal. You have ,ften heard people say that the body is a lachine. With respect to its operations, ie comparison is a good one. Your body, like a machine, runs on energy that it gets - lm different forms of fuel. Moreover, just as an automobile engine has an .haust and a coal furnace has a chimney, so your body has a means of getting rid of its wastes.
Most of this waste is made up of undigested or unabsorbed remains of food you have eaten, and is removed at intervals from the body through bowel movements. This is why it is important to have regular bowel evacuations.
Less bulky products of cell activity pass from the body through the agency of other organs. the most imponant of which are the kidneys. One should make sure that kidney wastes are properly and frequently eliminated. If anything happens to normal kidney functioning, wastes that are a threat to life witt back up in the blood stream.
Other sy tern in your body also remove wastes. As you know. in the act of breathing we get rid of till a different product of celt and tissue activity, carbon dioxide gas. mall amounts of waste material are carried off in perspiration. too Sweat removes salt. bel ping to keep the amount of that important mineral within normal limits. Although perspiration is generally not very important as a re?mover of waste. sometimes it is a valuable aid. For example, in certain diseases sweat production may be stepped up greatly. so that the w rk the kidneys must do is made less. In this way the kidneys have a chance to recover.
The role of digestion. Digestion is the process of changing the food we eat intO forms in which the body can use it. The work is done both chemically and mechanically. You witl study the entire process at greater length in Unit 5. But at the moment you need to have some idea of what goes on in order to understand how digestion affecu the ways that wastes are removed from the body.
Because of the chewing that food gets in the mouth and the churning it gets in the stomach, solid pieces are soon turned into a thick liquid. Not all vegetables are completely broken down, but their fibers beeom much softer. The liquid is re?leased in irregular spurts into the fir t pan of the small intestine by a muscular valve in the lower end of the tornach.
Hydrochloric acid formed by special cells in the stomach begins to break down the food there. but most of the digestiv chemicals are mixed with the food in the small intestines. These include bile and special ferments from the pancreas and intestine. They all help to change proteins. tarches, and fats into forms in which can be absorbed and u ed by the body.
These chemical rreatments make the food stream even more watery. From this liquid in the small intestine the various food elements pass into the body by absorption. By the time the large intesline is reached. most of the digested food has been absorbed. What remains moves into the large intestine in a rather watery solution. The water is absorbed through the walls of the large intestine. The solids are gotten rid of in the bowel movement.
In the course of digestion, fermenta?tion takes place, with the production of various gases. In addition, bacteria multiply as they work upon the remaining bits of food in the intestines.
A small amount of food is absorbed in the large intestine, where the food stream remains longer than in the small intestine. Its principal function, however, is absorption of water. Most of this absorption occurs in the first part of the intestine, on the right side of the abdomen.
Intestinal wastes. The wastes, or feces, discharged from the large bowel at its outside opening, the anus , are made up chiefly of what is left of the food we have eaten. They also contain mucus from the cells lining the inside of the small intestine, dead cells (which are constantly being shed), and large numbers of different germs, which are to be found in the intestinal tract at all times.
Regularity. For many years, there has been controversy over whether decemposing food products are harmful if they remain in the body for any length of time. On one side, we have those who point out that the body can make many dangerous substances harmless by chemical action. Some say that the action of germs on food is helpful to the body because it produces important ferments and vita?min elements.
However, most people feel some abdominal distress if the large bowel is not emptied regularly. Or they may have headaches, lose their appetite, not be able to concentrate, feel dull and irritable. Not everybody will agree that these reactions are real rather than imagined. But since they are so widely believed to occur, it is perhaps just as well to assume that as you have read-daily bowel evacuation is desirable.
It is wise not to be over-concerned about this matter. Set up the habit of daily bowel movement, but do not look on an ocasional interruption in the routine as a cause for worry.
The most common reason for constipation is that one fails to encourage and respond to the natural tendency of the large bowel to empty itself from time to time. If you are "too busy" Or always have something else you want to do first, the natural impulse, or reflex habit, may be dulled after a while. As this begins to bother you, you may resort to laxatives, sometimes using substances that are far more violent than they need be; It is easy for people to grow more or less dependent upon such aids. The bowels become irri?tated and often react by slowing down their normal activity. Then the person takes more laxatives. So the circle goes round and round. The body systems remain Out of balance.
Importance of your kidneys. It is apparent that the kidneys are of great value to our bodies. There is no other organ in the body. except perhaps the liver, that performs so many and such important services. The kidney is sometimes de?scribed as a filtering station through which water passes from the blood and is excreted as urine. But the job of the kid?neys is not limited to this important function. Besides straining wastes and excess water from the blood. they regulate the concentration of certain salts in the body.
You have two kidneys, each of which weighs about half a pound. Though small, your kidneys are of the greatest importance in helping to keep the body operating properly. They are. in fact, so important that if their work is affected by disease or injury, a person's life may be in danger Kidney disease, in various forms, is one of the ten leading causes of death in this country.
Nature has done her best to make sure the work of the kidneys is carried on suecessfully by providing you with two. Should the need arise. it is possible for you to live an entirely normal life with only one kidney.
How your kidneys are protected. The body itself seems to treasure the kidneys. they are sowell-protected. For one thing, they are cushioned in a special layer of fat. This fat is never used by the body as fuel, even though great loss of fat may occur elsewhere.
The kidneys are also protected by their location. They are close to each side of the spinal column. just under the diaphragm. The lower ribs and the wings of the vertebrae guard the kidneys in the back. Heavy layers of muscle in that area also help.
The kidneys are kept from moving about too freely by strong bands of s. brous tissue. These bands are attached to the diaphragm, so that the kidneys move a little as you breathe. In from. your stomach and intestines serve as a soft shield, Sometimes it happens that the fibrous bands are relaxed, allowing one or both kidneys to move rather freely. This is known as a "floating kidney," It can be corrected by an operation in wh ich the bands are sewed more snugly into place, or by the wearing of a' special abdominal pad.
How your kidneys work. As you read the following description of the kidney, you will want to check it with the diagram.
A kidney is made up of two pan.s, the cortex and the medulla. If a kidney is split open, as in the diagram, the difference between the two pam can be seen by the naked eye, although the fine details can be made out only with a microscope. The cortex, which lies at the outer edge of the kidney, has a solid, compact appearance. The medulla, in the center of the kidney, looks like a group of wagonwheel spokes. The "hub" upon which the cortex and the medulla converge is called the hilus of the kidney.
Packed tightly in the cortex are thousands upon thousands of microscopic balls of tissue, each known as a glomentlus . The glomeruli remove water and various other materials from the blood. In one minute as much as half a pint of blood may pass through the capillary networks of the kidney.
The glomeruli work fairly steadily at their job of filtering and extracting ma?terial from the blood, but at times the rate changes. For example, you can speed up their activity simply by drinking large amounts of water.
A tube, or tubule, as they are called, leads from the mouth of the glomerulus sac through the medulla. As the fluid passes steadily along the spokelike tubes of the medulla toward the hilus of the kidney, it is changed chemically. Find the tubules in the diagram.
Each glomerulus and each tubule processes only a few drops of urine at a time. But there are so many of them that they are able to extract from the blood and pass on to the bladder about one and one-half quarts of urine every twenty?four hours.
As shown in the picture, the upper end of the ureter fits snugly around the hilus of the kidney. The ureter is a thin-walled tube. It is quite wide at the hilus, but narrows quickly, and then has a diameter about the size of a Straw. Urine travels Chiefly by the aid of gravity down the ureter to the bladder. In spurts and driblets, it enters the bladder, where it is stored until it is discharged.
Normal urine is slightly heavier than water. It is acid in reaction. Some of the substances it contains m.ay settle out if the urine is allowed to stand. Normal urine should contain no blood, albumin, or sugar. It is usually tested for the presence of these substances in routine laboratory examinations.
Disorders of the urinary system. There are many things that may upset the delicate and intricate kidney system. Sometimes a faulty growth of the organ takes place several months before a child is born. Or infection in the tiny glomeruli the tubules may cause inflammation or destroy cells.
Infeerions may also occur in other parts of the urinary system. These infections are often encouraged by obstructions in the passageways. Today, thanks to new medicines, most infections can be cleared up quickly. The obstruction must also be cleared up, however.
The obsrructions are of many different kinds. The ureters may be narrowed by muscular contraction (spasm) or by some irritation of their delicate walls. Folds of tissue may form on the inside of the bladder. Sometimes a kidney is so movable that it drops down enough to cause a kink in the ureter. A Slone somewhere along the way may also block the urinary flow. If a small stone gets into the ureter, it may eventually shut off the flow cornpletely. Stones of many sizes and shapes may form in the urine of people who have a tendency to them, but most are passed, without much difficulty, as very small particles.
Smnming up. Your body must perform a good number of functions automatically and continuously. The endocrine glands secrete hormones that help to regulate these functions, so that you grow and develop. The secretion of some hormones, particularly of adrenin, is influenced by your emotions.
In order for you to live, your body must burn fuel for energy and heat. To do this, it requires a constant supply of food and oxygen. Blood carries digested food and oxygen to the cells and takes waste products away from them. It is pumped through the body by the heart and circulates through a complex system of vessels. Arteries carry oxygenated blood away from the heart to the tissues. Veins transport blood carrying waste products from the tissues. Small blood vessels in the tissues are called capillaries. In the capillaries of the lungs blood is purified; that is. carbon dioxide is exchanged for oxygen. Impurities are also removed from the blood by the kidneys and the liver.
The excretory system removes food that cannot be absorbed by the body. and the waste products of oxidation. It does this chiefly by means of the kidneys and the large intestine. It is important that the waste products be discharged regularly.
The vital organs of your body are nor?mally hardy and well-protected from in?jury and disease. However. disorders may arise. Those that are serious will require medical attention.
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Last Updated ( Sunday, 02 March 2008 )
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