Your blood: The key to life

By Al Lowe
Contributor

Your blood is the key to almost all of your body functions. It is not just a fluid which moves around inside you, but a 'soup', containing many kinds of cells, dissolved substances and much, much more.
Your blood contains red cells - erythrocytes. These are what makes blood red because they contain hemoglobin. Hemoglobin contains iron. It is also the chemical which carries oxygen from your lungs to the rest of your body, and a good deal of the carbon dioxide back again.
Why hemoglobin? Well, oxygen attaches itself very, very easily to hemoglobin, and it is also released very easily. One single red blood cell can attach to itself over a billion oxygen atoms.
Blood carrying oxygen is bright scarlet, but with carbon dioxide, it is much darker. If you are a man, you may have about 30 billion red cells in your blood. If you are a woman, you will have about 15 to 20 percent less than that.
You also have a lot of white cells in your blood. They are called leukocytes. Compared to red cells, they are fairly large. But they have the ability to change shape (much like the one-celled amoeba you may remember from high school). This enables them to squeeze through the tiny pores in the walls of blood vessel. This activity is very, very important since one of the main functions of white cells is to find and destroy disease germs. Many of these white cells simply 'swallow' disease bacteria and digest them. The pus which forms around a wound is made up largely of worn-out blood cells. Most white cells are produced in the marrow of bones.
The liquid part of blood, called plasma, is a yellowish fluid. It is about 90% water, and carries a host of things around, in addition to the cells and platelets. Among them are: digested food from your intestines, bound for cells which need nourishment; minerals and vitamins; urea, a waste product, headed for your kidneys; hormones, the messengers which trigger so many reactions in your body; carbon dioxide and oxygen, dissolved in the plasma itself; heat to keep your body at a fairly steady temperature; and a whole host of other things besides.
You don't really have an awful lot of blood in your body. An average women may have about four or five liters (about one Imperial gallon), and an average man perhaps 20% more than that.
Blood has been the symbol of life since history began. Cloaked in mystery and superstition, it has been associated with hundreds of pagan rites and sacrifices.
We know a lot about blood nowadays, and researchers find new information all the time. This essential fluid is truly 'the river of life.'