Karen Freed, aged 11, of Los Angeles, California for her question:
What makes blood red?
A drop of blood is a most beautiful red‑red color. You can forget a scratch gust long enough to admire it. Through the skin, some blood vessels look blue. These are the veins carrying blood back to the heart and lungs. Yet if you cut a vein, the blood that oozes out is not blue or purple. It is also red. Blood is reddest when it leaves the heart. It is somewhat darker as it returns. The veins look blue as seen through the akin. But all our blood is red, red, red.
Blood is a watery fluid teeming with tiny passengers. The passengers are little cells called corpuscles. You need a, microscope to see them singly. Most of them are red‑red and a few are whiteish. There are also even smaller passengers called platelets. The little platelets do their ,fob when blood. flows through a scratch‑or cute they seal up the wound by wadding the b1ood into a clot.
By far the greatest number of passengers in the flowing blood are red cells. Under the microscope they show up like little round flat bags. It would take you ages to count the number of red cells in one drop of blood. For there are three hundred million of them in each drop of healthy blood. An adult has about five and half quarts of blood forever flowing through his body. The red color of blood comes from the trillions and trillions of tiny red corpuscles.
Each little red bag is filled with a stuff called hemoglobin ‑ a magic brew of iron and protein, The red pigment is in the special form of iron. Oxygen brightens the hemoglobin. This is why blood is reddest when it leaves the heart. It is then loaded with fresh oxygen snatched from the spongy lungs. It darkens somewhat as it exchanges its oxygen for waste carbon dioxide. That is why the blood in the veins is darker,
Each little red cell lives a life of its own. It works day and night toting supplies and removing waste throughout the body. It begins its life in the marrow of the bones where it is manufactured. It enters the blood stream full grown and lives its circulating life for about 127 days, when it is worn out, the body disposes of it.
The worn out red cell goes to the spleen where it is broken up. The pieces are sent to the liver. The liver scraps the coloring matter by sending it into the intestines. But it saves the precious iron. This it sends back to the bone marrows. These busy factories reuse the iron to manufacture new red cells.
Every day a certain number of old red cells are scrapped. Every day a certain number of new red cells are ready for launching. The body takes care of all this wonderful work for itself. All we have to do is to eat and enjoy plenty of the right kind of foods. Salads, vegetables especially green vegetables ‑provide the stuff necessary to make those bright little bags of hemoglobin which keep the blood red.