RED BLOOD CELLS – GAS CARRIERS
Red blood cells (RBC) have the responsibility of transporting oxygen throughout the body. A single drop
of blood contains millions of red blood cells which are constantly traveling through your body delivering
oxygen and removing carbon dioxide waste. If they weren't, your body would slowly die.
A typical RBC is about 6-8 micrometers in diameter, about the same as the width of a spider web strand.
An RBC is concave on both sides like a miniature donut where the hole in the center doesn't go all the way
through. The small size and flexible shape allows RBCs to squish into the capillaries where your blood
vessels are the smallest. Without this ability to flex, they would easily get stuck and block circulation.
RBCs are red only because they contain a protein
called hemoglobin which is bright red in color.
Hemoglobin is a large and complex protein in red
blood cells that contains four atoms of iron, making
it an excellent vehicle for transporting oxygen and
carbon dioxide. Each red blood cell contains about
250 million hemoglobin molecules. Since each
hemoglobin molecule can carry four oxygen
molecules, the potential exists to transport one
billion molecules of oxygen in each red blood cell.
There are two reasons for the need for such a large
amount of hemoglobin in our blood. First, oxygen
does not dissolve very well into our blood. Second, the demand for oxygen is extremely high in our body.
As the blood passes through the body's tissue, the hemoglobin releases the oxygen to the cells. The empty
hemoglobin molecules can then bond with the tissue's carbon dioxide or other waste gases, transporting it
away.
Over time, the red blood cells get worn out and eventually die. The average life cycle of an RBC is 120
days. Marrow in the center of many of your bones continually produces new blood cells to replenish your
supply. Since the human body is continually making more blood, it is safe for healthy adults to donate
blood. Initially after giving blood, the donor may feel some momentary lightheadedness due to the loss of
oxygen-rich red blood cells and blood sugar, but the body quickly stabilizes itself.
Extra Reading: Some Red Blood Cell Conditions
Anemia is a condition that develops when your blood lacks enough healthy red blood cells or hemoglobin.
If you have too few or abnormal red blood cells, or your hemoglobin is abnormal or low, the cells in your
body will not get enough oxygen. Symptoms of anemia -- like fatigue -- occur because cells in organs aren't
getting what they need to function properly. Anemia is the most common blood condition in the U.S.; it
affects about 3.5 million Americans. Anemia may be due to blood loss, disease, iron deficiencies or
heritable conditions that reduce blood cell production or increase blood cell destruction.
Carbon monoxide poisoning occurs because carbon monoxide (CO) is structurally very similar to oxygen
(O2) and hemoglobin binds to both. In fact, carbon monoxide is hundreds of times more attracted to
hemoglobin than oxygen. If you inhale too much CO, then it takes over the iron binding sites on the
hemoglobin and doesn't allow space for oxygen to hitch a ride. In essence, you end up suffocating because
the oxygen you co the tissues in your body.