Blood Cells Are Your Best Friends Forever

Red cells circulate in the most numbers. This means there are more red cells than any other blood cell in the circulation. In fact, there are more red cells in your body than people on the whole planet earth. Red cells have another more formal name: erythrocytes (e rĭth rō sīts) but most people just call them red cells. What Do Red Cells Look Like? If you look at a single red cell, it will have a faint reddish-orange color but when you put several million of them together, they are quite red. Meet Fred the Red Cell. In order to do their job, red cells have to be able to squeeze through very tiny spaces and so they have to be very flexible. To be this flexible, they need more membrane (skin) than absolutely necessary. For that reason, the adult red cell is “biconcave”. That means that it has a round dimple on both sides Can you see why the adult red cell has been described as looking like a donut or a bagel? The other feature of the red cell that makes it more flexible than other cells is the fact that it gets rid of its nucleus before leaving the bone marrow where it was born. A nucleus would make it impossible to squeeze through those small openings. A Red Cell’s Job Oxygen is the food that all cells need in order to do their job. Without oxygen, cells will die. When you breath in, you are taking oxygen into your lungs. Since there are a lot of cells in the body that are fixed in one spot and can’t go to the lungs to pick up oxygen, there has to be some way to bring the oxygen to them. That is where red cells come in. The main work of the red cell is to carry oxygen (food gas) from the lungs to all parts of the body and to return to the lungs with carbon dioxide (garbage gas). When you breath air into your lungs, millions and millions of red cells are there waiting to pick up the oxygen so they can take it to all parts of the body such as your brain and your heart and your little toe. If your brain is starved for oxygen, you will pass out and even die. If your muscles don’t get enough oxygen, you would feel pain and wouldn’t be able to move. By taking the carbon dioxide waste back to the lungs, the red cell keeps the inside environment from getting polluted (too acid). You get rid of the carbon dioxide when you breath out. Trees and other plants in the outside environment love carbon dioxide and so everyone is happy. How Do Red Cells Do their Job? Red cells don’t go around carrying buckets of oxygen. If you look inside of a red cell you will see a lot of little lumpy balls floating in salt water. These are molecules of hemoglobin. They were made by the red cell when it was very young and still with its parents in the bone marrow. To make a molecule of hemoglobin the baby red cell followed a recipe that was in its DNA and put together a long string of little building blocks called amino acids to make a protein. These amino acids have different shapes – some have long arm-like structures and others have bends or angles. Some of these amino acids are attracted to each other and others can’t stand each other. All of this causes the string of amino acids to fold on itself several times to make a lumpy looking protein. To make a molecule of hemoglobin two different pairs - or a total of four - protein chains are put together to make a lumpy looking ball. Each protein chain has a deep pocket inside where the red cell puts a ring with the mineral iron in the middle. The ring is called heme and the four protein chains are called globin. Put them together and you get hemoglobin. By the way, it is the heme ring that is red and gives the red cell its color. When oxygen passes into the red cell through its membrane (skin), it finds its way into the hemoglobin molecule and tucks itself next to each iron molecule (4 in each molecule of hemoglobin). Oxygen stays there – safe and sound – until the red cells gets out away from the lungs and out where other cells are begging for oxygen. The oxygen is released from the hemoglobin, goes out through the membrane and into the cells that need it. Where Do Red Cells Come From? Red cells are born in the bone marrow (a place in the middle of your bones). There are several generations of cells before the red cell (like parents, grandparents and great-grandparents) but I’ll just mention a few. In order for cells to make more cells, they have to divide. This is called “mitosis” and is a complicated process during which they duplicate the DNA that is in their nucleus and then divide into two daughter cells, each with its own nucleus and DNA. The first generation is often called a Stem Cell. The Stem Cell can make all kinds of blood cells including red cells as well as other cells like those that line arteries and veins. The Stem Cell is also pretty special because it can make more of itself (something no other cell can do). When the Stem Cell gets the message that more red cells are needed, it will make the red cell’s grandmother who can make most blood cells except a few types of white cells. The red cell’s grandmother then makes the red cell’s mother who is capable of making both baby red cells and the baby of another cell family that we’ll talk about in the next chapter