Cathy MoClendon. age 9 of Englewood, CO:
What does the blood consist of?
The blood is a busy stream. Round and round the body it goes flowing through its. system of tubes and tunnels. Most of the body is made of small solid cells. They stay put. These little units need the blood stream to work together as one body. The blood is a delivery man and a garbage man. It carries food and fuel to the working cells. It gathers up their ashes and wastes and‑totes them away.
The base of the blood is a liquid called plasma. Much of the plasma. is water. Dissolved in it are proteins and chemicals useful to the cells. It teems with corpuscles ‑ the red and white blood cells. The red cells are present in trillions. A cubic. inch of healthy blood has about 75 million of hard working red cells. They give the blood its red color.
Each red blood cell is a tiny coin‑shaped body. Its rim is mush thicker than its center. Lined up on the flat side 30,000 of them measure one inch. Stacked like plates one above the other 80,000 of then measure one inch. They are filled with a stuff called hemoglobin. Hemoglobin has a lot of iron atoms which can form a loose bond with atoms of oxygen.
Red blood cells come in contact with oxygen on their trip through the lungs. There they give up carbon dioxide and take on a fresh load of oxygen. The. blood stream hurries them along to deliver this fuel to the waiting cells. They are rushed through the branching blood vessels all over the body. The big arteries divide into smaller arid smaller blood vessels. The smallest capillaries are just big enough to let the little delivery men through. The busy cells collect up the oxygen and deliver up their ashes of carbon dioxide. The delivery men now turn garbage men and tote the waste back to the lungs.
White cells are also present in the blood stream. They are bigger than the red cell.. and come in different sorts and shapes.. Their chief job is healing. They can move on their own and tend to cluster around wounds rind bruises. They can squeeze right into the cells and engulf germs. When germs invade the body the white cells multiply, though usually there are 500 times more red than white corpuscles.
One kind of white cell forms plotting. This is the triangle.‑shaped platelet; It takes over when the blood oozes from a scratch or cuts It dissolves in the air. Then by some magic of its owns it releases. a mass of fine elastic threads. The red cells are trapped to form a scab which plugs up the wound.
Blood cells are manufactured in the marrow of the bones. When their busy life is over they go to the spleen and the liver to be broken up. About ten per cent of the red cells are replaced every day. Some of the precious Iron in them is saved and used over again.. But we need plenty of the right foods to make sure of a proper supply of red yells. So don't pass up the spinach the lean meat and the egg yolk.