One of the fascinating stories of the body is that of the blood and its circulation. The role of the bloodstream, its composition, and its functioning has interested scientists for many ages. While the bloodstream is the medium through which oxygen and nutrition are carried to the cells and through which their waste products are eliminated, it performs many other valuable functions. It helps to regulate the heat of the body, distribute the secretions of the internal glands, maintain the acid-base balance of the system, and protect the body against what is commonly known as infection.
That the blood plays an important role in maintaining the health of the body was known long before Dr.
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Harveys monumental discovery of the circulation of the blood. However, this discovery opened new vistas, helped to clear up many problems, and made possible a great deal of additional progress.
Today the importance of the blood and its effect upon our health and well-being are fully recognised, and it is now known that any impairment in its competition or functioning will vitally affect the body as a whole.
When we talk of the blood, we talk of a vast world teeming with countless microscopic entities known as the blood cells. This enormous population confined within the blood vessels lives and functions in a sea of fluid known as the plasma. About half our blood is composed of plasma, while the other half is made up of the blood cells that live and work in it.
Two types of blood cells inhabit this strange world‚ the red and the white. The red blood cells pick up the oxygen in the lungs and carry it to all the cells of the body, while the white blood cells fight off infection or foreign matter.
For one to visualise the prolific life existing within our bloodstream it should be sufficient to mention that each cubic millimeter of blood in the average healthy human body contains about five million red blood cells and between seventy-five hundred and ten thousand white blood cells. The count of the red blood cells may vary somewhat with the individual. In women we may find about four and a half million, while in a newborn infant the count may run as high as six to eight million per cubic millimeter.
The count of the white blood cells increases considerably during so-called infection and falls back to normal when the infectious process clears up.
Since the average adult body contains about six to eight quarts of blood, we can readily visualise that the number of red and white blood cells living and working within the confines of our body reaches astronomical figures.
As is well known, the blood vessels are airtight to prevent air from coming in contact with the blood. In case of injury, the blood of a healthy person clots quickly when coming in contact with the air and this seals the wound. The blood contains such clotting substances as thrombin, prothrombin, thromboplastin, ionised calcium, and fibrinogen, which make it clot whenever it comes in contact with air. In case of injury this protects us against hemorrhage.
When some of these elements are not present in the blood in adequate amounts or when an imbalance exists, the blood may not be able to clot properly, and in case of injury we would be in danger of bleeding to death. On the other hand, under certain conditions the blood may tend to clot too quickly, and then we are in danger of blood clot formation. This is the condition that exists when cjots form in the heart, the brain, or the extremities.
In the healthy body the clotting mechanism is in perfect balance and the problem of too rapid or incomplete clotting of the blood arises only when our health has become impaired sufficiently to upset this balance.