Paul Buchanan, age 17, of Shawnee, Oklahoma, for his question:
How does the body protect the heart?
The news reports of human heart transplants have led many Andy readers to wonder about the way their own hearts work. We now realize how important the heart is to life. We start wondering how well this precious organ is protected and maybe what we can do to keep it secure.
Your busy heart beats about 70 times a minute, day and night, year after year. You do not have to tell it to beat because it is made to operate automatically all by itself. You can feel its steady pulsing in the blood vessels of your wrist or throat. If you check your pulse rate often, you will notice that it is faster after a brisk exercise or perhaps after you get an upsetting emotional surprise. The pulse tends to slow down when you body rests or sleeps. The heart has many, many other smooth automatic operations to suit its work to the body's needs.
Naturally the body is built to take good care of its precious, one only heart. This busy organ is a fist of sturdy muscles hidden from view and safely buried deep inside the chest. This inner region of the body is protected by a bony cage of ribs. A blow on the chest may bruise the outer covering of skin and flesh, but the strong rib cage protects the heart inside from all but the most severe wounds. The ribs are attached to the spine and all these bones are pliable so that the beating heart is not sealed into a solid, unmovable box.
The heart shares the safety of the rib cage with the lungs and other soft internal organs, and it may come in contact with these organs as it beats. To protect it from chafing against them, it is encased in a bag of strong skin tissue called the pericardium. This word means "around the heart." The pericardium acts as a pad against chafing and also keeps the heart neatly encased in its proper shape. The inside of this well fitting jacket has a smooth lining that oozes a slippery substance. This protects the constant beating heart from chafing against its own skin.
The rib cage and the pericardium protect the heart from blows and chafing. But the heart also requires supplies of oxygen and nourishment, plus a way to get rid of waste materials and to repair a certain amount of everyday wear and tear. The healthy heart takes care of these problems with its own network of blood vessels, which nourish it with food and oxygen and carry away the wastes from its busy activities. Its blood supply also carries soothing chemicals to strengthen weakened cells and heal small damages. A healthy heart can repair most of its minor ailments. And it does all this protective and repair work automatically, along with the complex round of duties it performs to keep its one only body alive.
The body of course is made of countless living cells that require oxygen to carry on their vital chemical activities. They depend on the circulating blood stream to carry oxygen and dissolved nourishment to their very doors. The streaming blood also totes away their waste materials. The beating heart is the living pump that keeps the stream constantly circulating on its busy rounds.