The fluid in which the blood cells (erythrocytes, lymphocytes) swim is known as plasma. This is no simple liquid, but a special compound containing a great many special substances. Plasma consists of 92% water, 6% to 8% protein, and quantities of dissolved salts, glucose, fat and amino acids, carbon dioxide, nitrogenous wastes and hormones.
Plasma distributes the nutrients you obtain from the food you eat throughout your body. It also carries waste products that cells produce to the relevant organs in order to expel them from the body. . . If plasma did not have this responsibility of transport and delivery, then the food you eat would serve no purpose, nutrients would not reach your tissues, and your body would swiftly become poisoned because the waste products it produces could not be expelled.
Among the plasma’s other tasks include:
• Ensuring blood pressure is kept at a specific level,
• Assisting in the equal distribution of heat in the body,
• Maintaining the acidity of the blood and other tissues at a specific level.
Plasma proteins each have very different functions. They come in three main forms: albumin, fibrinogen and globulins.
Albumin is the most numerous plasma protein. It performs a sort of carrying service in the body. Albumin’s most important function is to prevent excessive liquid passing from the capillaries to the surrounding structures.13 In order to understand the importance of this, look at the path traced by nutrients in the body. In order for them to reach the requisite tissues from the arteries, nutrients must cross the tissue wall, which possesses very small pores.
Nevertheless, no substance can cross that wall by itself. What matters here is blood pressure. Just as in a sieve, the liquid plasma component of the blood and the smallest molecules cross the wall under pressure. If there were no such barrier and these substances were able to reach the tissues in excessive quantities, then edema would form in the tissues. Albumin absorbs the water just like a sponge, and due to its high density in the blood, it thus forestalls that danger.
Water and most dissolved substances are able to cross the capillary wall with ease. But this is not possible for proteins. For that reason, such proteins as albumin remain inside the vessel at the point of transition and prevent liquid from seeping out. Albumin binds to itself fats such as cholesterol, hormones and yellow bilirubin, a poisonous bile-duct product. In addition, it binds onto penicillin and some other drugs, refusing to let them to pass. It deposits toxins in the liver, and carries nutrients and hormones to the places in the body where they are needed.
Fibrinogen, another protein in plasma, plays an important role in blood clotting. Yet another protein in blood, the gamma globulins, transmit protective substances such as antibodies that form in response to the body’s being stimulated by a particular infection.
These are just a few of the proteins in the blood. In addition, gasses such as oxygen, nitrogen and carbon dioxide are also present in dissolved form in plasma. Glucose, one of the solid substances in the blood, is also very important, being used as fuel for the brain and muscles. For that reason, its level in the blood is regulated by hormones. If the glucose falls below a specific level, trembling and fainting ensue, followed shortly afterwards by coma, and often death.
Each of these substances, of such exceeding importance to human life, is the product of a very special creation, as becomes clear when one considers their functions and characteristics.
As you have seen, there are close interrelations between the substances in the blood. The absence of just one of these substances of vital importance to all human beings, or its presence in the wrong amount or with different properties, leads to serious problems in the body. This shows that all the properties of blood were created together by Allah.