Blood: The River Of Life That Flows Through Your Body

Many needs in all living things—such as carrying nourishment and gasses like oxygen to the cells, and eliminating waste products from the body—are met by substances carried by the circulatory system. In human beings, the liquid that performs all these functions is the blood. Every single cell in your body, from a skin cell on your fingertip to the specialized retinal cells in your eyes, depends on what blood provides.

Blood flows through the arteries and veins that interpenetrate the body like a transport network or river delta, visiting every single corner of the body. During its travels through the arteries, that river carries numerous substances that the cells require. We can think of these as cargo packages carried by the river, containing food, water and various chemical substances. The most urgent package to be delivered is oxygen, because if deprived of oxygen, cells will soon die. Thanks to the specially constructed system in your body, however, the packages are delivered to every cell in time and to the correct “addresses.”

You seldom feel the flowing of this river during the course of your day-to-day life. However, the human body has been created with such a consummate artistry that though everywhere is interpenetrated by blood vessels, they are invisible from the outside. That is because the 2-mm (0.07-inch) layer of skin that covers your body conceals the capillaries in a masterly fashion.1

That epidermal layer is actually so thin that the slightest scratch will cause some blood to leak through it. Were the vessels not covered by a very fine and attractive skin, there is no doubt that even the most attractive people in the world would appear hideously repellent.

Blood performs a great number of vital functions inside the body, such as carrying waste and toxic substances to the liver, supporting the immune system, regulating body temperature rather like an air-conditioning unit, and carrying nutriments to the relevant regions. Communication via hormones within the body is also performed almost entirely by the blood.