So let’s talk about the real red blood cells for a moment. In medical slang they are called RBCs; but technically they are called erythrocytes (eh-RITH-ro-sites).
This unpronounceable-looking word is the fusion of three Greek words: erythros meaning “red,” kytos meaning “hollow,” and cyte which we use for “cell” in the modern world. So RBCs are little red bags. And so they are, as you will soon see.
RBCs are part of blood, which author Elaine N. Marieb eloquently describes in her book Human Anatomy & Physiology as “the river of life that surges within us, transporting nearly everything that must be carried from one place to another.” Blood is made up of almost 45% RBCs and almost 55% plasma (a non-living liquid that the RBCs “swim” in). The not-quite-one-percent left over are the germ-fighting white blood cells and platelets—the stuff that stops bleeding when something goes wrong with a blood vessel. Fun trivia: blood accounts for 8% of your body weight. Fun trivia number 2: if we unraveled your entire circulatory system it would stretch 60,000 miles!
So back to our friends the RBC. Our author William “Lee” Dubois describes red blood cells as “the FedEx
trucks of your body, moving oxygen from the lungs to the cells and carrying out the trash.” He confesses that he’s never seen the FedEx guy take out the trash, but you get the idea.
RBCs offer both drop-off and pick-up services. They deliver oxygen from the lungs to each and every cell in your body, and while there pick up the carbon dioxide waste and return it to the lungs for disposal. A red blood cell is really little more than a living bag of hemoglobin, a protein that oxygen “grabs” onto.
Red blood cells aren’t actually “proper” cells at all. The adult ones have no nucli or organelles (crudely put brains and guts) unlike almost all other living cells.
Red blood cells don’t divide to reproduce themselves. They are built in the bone marrow inside your skeleton.
Every day your body produces 100 billion new red blood cells. That’s an ounce of blood, by the way. (You produce 2 million per second, we are told.)
Baby red blood cells are blue.
By cell standards, RBCs are small.
A single RBC contains 250 million hemoglobin molecules. Each hemoglobin molecule can transport 4 molecules of oxygen. All that math adds up to each RBC can carry a billion oxygen molecules.
RBCs look like miniature flying saucers, but they are more pancake than Frisbee. They can twist, turn, and even roll themselves up like burritos to get through capillaries smaller than they are.
RBCs don’t use oxygen themselves. Crazy!
Women have a lower red blood cell count than men do.
When oxygen rich, a red blood cell is described as “scarlet or ruby red.” When low on oxygen the cell is dark red.