The Red Blood Cells

The Red Blood Cells

The red blood cell is the most common cell in the bloodstream. It gives blood its red color and is thus called a red blood cell. Just one drop of the blood contains hundreds of millions of such cells. When viewed through a microscope, they look like doughnuts with a depressed center instead of a hole. Each cell is packed with hundreds of millions of hemoglobin molecules. Each hemoglobin molecule is, in turn, a beautiful spherical structure made up of about 10,000 hydrogen, carbon, nitrogen, oxygen, and sulfur atoms, plus four heavier atoms of iron, which give blood its oxygen-carrying ability. Hemoglobin facilitates the transport of carbon dioxide from the tissues to the lungs, where it is exhaled.

Another vital part of your red blood cells is their skin, called a membrane. This marvelous covering enables the cells to stretch into thin shapes so as to pass through the tiniest blood vessels and thus sustain every part of the body.

The red blood cells are manufactured in your bone marrow. Once a new cell enters the bloodstream, it may circulate through the heart and body more than 100,000 times. Unlike other cells, red blood cells have no nucleus. This gives them more space to carry oxygen and makes them lighter, which helps the heart to pump trillions of red blood cells throughout the body. However, lacking a nucleus, they are unable to renew their internal parts. Thus, after about 120 days, the red blood cells begin to deteriorate and lose their elasticity. Large white blood cells called phagocytes consume these worn-out cells and spit out the iron atoms. The scarce iron atoms attach themselves to transport molecules that take them to the bone marrow to be used in the manufacture of new red cells. Every second, the bone marrow releases two million to three million new red cells into the bloodstream!

Note: If trillions of red blood cells were suddenly to stop functioning, you would die within minutes.