That Amazing Fluid Within You!

MANY individuals are uncomfortable or squeamish about blood. Are you? You may want your blood ‘under your skin,’ that is, in your blood vessels where it should be. How right you are! That is where it belongs, for there it serves you every second. You are alive because of your blood. But just what is your blood? Do you know its parts? How does it serve you? Why is your blood uniquely your blood?

What It Is

You have seen your blood, perhaps more often than you would prefer. It may appear to be simply a red fluid. But note what the Encyclopædia Britannica (1974) says about it:

“The blood has an almost unbelievably complex structure, and many components participate in its functional activities, often in an intricate and poorly understood way.”

In some senses your blood might be illustrated by a glass of iced lemonade. Basically, lemonade is water in which lemon juice and sugar are mixed or dissolved. Also, some pieces of ice and lemon pulp float in the liquid. Your blood is similar. It is a complex mixture with two basic parts. The largest part is the fluid or plasma. It is 91.5 percent water, but it contains hundreds of chemicals and soluble constituents, such as hormones, sugar, salts, cholesterol, proteins, minerals, and so forth. The other basic part of your blood is the “solids” or formed elements that are carried in the plasma.

Your blood system as a whole and also its individual components perform a vast array of important functions. Are you aware of some of them? Well, as we discuss the blood components watch for the six main functions of this complex fluid.

Your Red Blood Cells

Have you ever wondered why your blood is red? That is because of the red cells (erythrocytes) in your blood. In one cubic millimeter, about as big as the dot on an “i,” a man has some five million red cells. You have about half a million less if you are a woman. Each red cell is a tiny rounded disk that is slightly indented on the two sides. You cannot see them with the unaided eye, for it would take 3,200 of them placed side by side to measure an inch (2.5 centimeters).

Without any conscious effort you are constantly forming these important red cells in the bone marrow of your ribs, skull and vertebrae. Why? Well, each second some 1.2 million of them wear out and are removed by your spleen and liver. Yet, the iron and other important materials of your worn-out red cells are used in various ways, including the making of new cells.

What, however, are your red cells doing during their “life-span” of about four months? Respiration is their key function. You may associate respiration with your lungs. Yet how does the oxygen in the air you breathe get from your lungs to the 60 trillion cells of your body? Your red cells rise to the occasion. In your lungs each red blood cell picks up oxygen, just as a truck might load up at a warehouse. A red cell contains an iron-rich protein called hemoglobin that oxidizes or “rusts,” as it were, in your lungs, that is, it unites with oxygen, becoming bright red. Then comes a quick trip to deliver this to the customers, your body cells. From your lungs the blood speeds to your heart, where it gets a strong push, carrying it through progressively smaller arteries until it reaches the minute capillaries throughout your body. As each red cell passes single-file through a capillary, it quickly delivers up its cargo of oxygen and makes a pickup for the return trip. Your body cells then “burn” oxygen and nutrients to produce energy for you so you can move, think and keep warm. So in the brief passage through your capillaries the blood delivers oxygen and collects the by-product carbon dioxide, which is brought back to your lungs for discharging.

During a blood test your doctor checks as to whether you have a normal amount of healthy red cells. A shortage spells anemia. If that exists, it might mean that you need more iron-containing food in your diet. But a low red-cell count also alerts your doctor to check to see if you might be losing blood internally, as from a bleeding ulcer. Or a serious deficiency could be caused by some problem in your bone marrow. In any event, the condition should be investigated carefully, for there is no known substitute for red cells in bringing oxygen to your body cells.

White Blood Cells

Overshadowed in number, if not in importance, by their red companions are your white blood cells (leukocytes), some 5,000 to 10,000 in each cubic millimeter of blood. These, unlike the red cells, are independently mobile. They can move to where they are needed, either in the bloodstream or outside it. Simply stated, their crucial job is defense. Yes, they are constantly saving your life.

You have various types of white blood cells. Two of them, your granulocytes and monocytes, serve as ever-vigilant “policemen” within you. By accident you might scratch your arm, letting dangerous bacteria into your body. Immediately these “policemen” are alerted. They are able to pass through the walls of your capillaries and engulf invading bacteria, digesting them with potent enzymes. The pus that forms at the site of an infection tells you that they are on the job, for it consists mainly of white cells and defeated bacteria. White cells also respond if you have an infection inside your body, such as appendicitis. In fact, one way your doctor can confirm the seriousness of such diseases is by checking your white-blood-cell count. If it is elevated, it indicates that your white cells are rallying to fight an acute infection.

Another type of white cells, your lymphocytes, is involved with your developing immunity and with acquired resistance to infections. Somehow they recognize what is part of your body and what is foreign. For instance, if skin from one part of your body is grafted on another part, it will likely adhere and survive. But if the skin is from someone else, lymphocytes migrate to the area, recognize “That’s not mine” and begin rejecting it. They also have a “memory” that aids you to be immune to various diseases.

Your Platelets

Imagine trying to carry water in a sieve. Were it not for your platelets, it would be just as hard to keep the blood within the circulatory system. A platelet is a small, colorless and flexible blob of cellular material. Does that sound unimpressive? Well, what your platelets do certainly is not. If you cut yourself, within seconds platelets attach themselves to the injured area and to one another. Thus they plug the wound and stop bleeding. What “glue” causes them to do this at a wound but not inside your bloodstream? There you have another deep mystery. Also, they release factors that stimulate the formation of a more durable sealing clot.

If our simplified consideration of your blood’s “solids” or formed elements has impressed you with its importance, what about your plasma, the liquid part that is 55 percent of your blood by volume?

The Other 55 Percent

A tasty meal is a delight! But once you digest the food it must get to the cells in order to be useful to the body. Silently but efficiently your blood plasma does the job, thus providing nutrition for every cell in your body. It delivers carbohydrates, fats, proteins, minerals, salts and vitamins to where they are needed.

Your plasma does not come back from that delivery job “empty” either. Besides carbon dioxide, other wastes must be removed from the cells. Your plasma does this, thus playing an important role in excretion. For example, it transports urea and uric acid from your cells to your kidneys, where they are eliminated.

If you are too warm, capillaries near your skin open, allowing the blood to carry excess heat to the surface. Conversely, when it is cold the blood stays deeper inside the body and so conserves body heat. Yes, your blood contributes to temperature regulation; it helps to maintain a uniform body temperature of about 98.6° F. (37° C.).

Recall the role of the platelets in keeping your pressurized blood from escaping from your blood vessels. This important role is called hemostasis. The plasma contains a number of important substances or factors that also contribute to this, for they are vital in blood clotting. Hemophilia is a dangerous condition where one or more of these factors are missing. But this is rare. With most of us, when we cut ourselves or are injured, a very complicated process begins that results in a blood clot. Fibrinogen is an important protein in your blood plasma that plays a role in the wound’s being sealed by a tough layer of fibers and cells. Then no more blood escapes and the body can repair the damage.

Your plasma also contains albumin. It works to retain water in your bloodstream, thus keeping the plasma in a liquid state and flowing in your system. If you experienced edema or swelling of your body, a blood test might show that your albumin level had dropped, and so let water from your blood escape through capillary walls and accumulate in your body tissue.

When it comes to amazing aspects of your blood, we cannot overlook the globulins in the plasma. When harmful bacteria or viruses invade your body, your defense system reacts by producing special molecules called antibodies. These are contained in the globulins. The antibodies kill or neutralize the invaders, which are then eaten by your white blood cells.

What a memory these antibodies have! Scientists earth wide marvel over it. Perhaps as a child you had chicken pox. Even if you have forgotten the disease, your antibodies have not. As long as the antibodies are present and active, you are immune to having the disease again. If a chicken-pox virus invades your body, your antibodies immediately pounce on it. During your life you develop naturally an enormous number of different specific antibodies that protect you from many diseases.

Globulins and antibodies are sometimes used as a treatment when a person has already contracted a disease, such as diphtheria. Instead of taking the risk of allowing the disease to run its course, doctors might recommend accepting a serum prepared from the blood of an animal or human that already contains the right antibodies.

One of the most widely known things about human blood is that there are various blood types. You may have heard of ‘type A blood’ or some of the other common types, B, AB, and O. If a person with one blood type is transfused with another blood type likely he will become severely ill and perhaps die. So hospitals try to “match” his blood type with that of blood from a blood bank. So far fifteen different blood types have been identified.

But since your blood is so very complex, with unnumbered unique combinations of antibodies, hormones, proteins and other factors, can you expect that doctors truly can “match” your blood with someone else’s? In 1966, Science Digest observed: “It is estimated that only one transfusion in 10,000 is completely compatible, considering the number of known factors that make blood different.”

Since that was written, even more has been learned that shows how distinctive your blood is, different from that of any other person. Thus, in 1974, Readers Digest said:

“There is a growing probability that [a man’s] blood may be quite as distinctive as his fingerprints, different from all other bloods on earth. In fact, it might be possible to take a blood sample from each person in a large stadium right now, and then a year from now take another sample and assign each fan his proper seat—on the basis of individual blood characteristics.”

There is increasing realization in the medical community of the potentially dangerous reactions from transfused blood, to say nothing of the possibility of transmission of diseases such as hepatitis and syphilis by means of transfusions. These problems merely underscore the wisdom of the Bible’s prohibition against sustaining one’s life by taking in animal or human blood.—Gen. 9:3, 4; Acts 15:19, 20

There is no question that your blood is amazing in its composition and functions. Yet with just a basic knowledge of some of its components and how it daily sustains and preserves your life, you can well appreciate the Creator’s choosing blood as a symbol of life. He said: “For the soul [or life] of the flesh is in the blood. . . . That is why I have said to [you]: ‘No soul of you must eat blood.’”—Lev. 17:11, 12.