Did you ever send a valentine with the shape of a heart on it? Did you ever hear someone say, “That came straight from my heart?” People talk about hearts a lot. People have always known that hearts are very important. You have a heart. Your heart does not look like a valentine heart. Your heart is a pump. When you run very fast, your heart pumps hard and fast. You can feel your heart pumping, or beating.
THE HEART PUMPS BLOOD
Your heart pumps blood. Blood comes into the atria or top chambers of your heart. Your ventricles, or bottom chambers, pump blood out to every part of your body. Blood going out of your heart carries food and oxygen. Every part of your body needs food and oxygen for energy. You need energy for your body to work and for you to stay alive. Your heart pumps blood carrying food and oxygen through your arteries. Big arteries carry the blood to your legs and arms. The arteries get smaller and smaller the farther out they go. Little blood vessels called capillaries take blood to your cells. Everything in your body is made of tiny cells.
WHAT HAPPENS TO THE BLOOD IN VEINS?
Your veins carry blood back to your heart. The chambers on the right side of your heart take care of blood coming back through your veins. First, the blood comes into your right atrium, the top chamber. Your right atrium pumps the blood into your right ventricle, the bottom chamber. Your right ventricle pumps the blood through an artery into your lungs.
WHAT HAPPENS TO BLOOD IN THE LUNGS?
Your blood has to get rid of carbon dioxide. It has to get a fresh supply of oxygen. Your lungs take care of both jobs. Carbon dioxide from your blood goes into your lungs. Your lungs get rid of the carbon dioxide when you breathe out. Then you breathe in. Your lungs get oxygen from breathing in air. Your lungs fill up with oxygen. Your blood picks up a new supply of oxygen from your lungs. Now your blood is ready to go out through your arteries to all the parts of your body.
HOW DOES THE HEART PUMP?
Make a fist. Open your fist slightly, and then squeeze it closed. Open and close your fist again and again. This is sort of how your heart pumps blood. The muscles in your heart squeeze the chambers. To open and close your fist, you have to think about doing it. You don’t have to think about squeezing your heart muscles. Your brain tells your heart to pump over and over again. Your heart pumps when you are awake. Your heart pumps when you are asleep. Your heart pumps faster when you run fast. Your body needs more oxygen when you run. Your heart is better than any pump made. It beats over and over again, day and night. The heart of a 76-year-old person has beat nearly 2.8 billion times. It has pumped about 179 million quarts (169 million liters) of blood. No one can live if their heart stops beating for more than a few minutes.
HOW TO KEEP THE HEART HEALTHY
Hearts can get sick. The special arteries that bring blood and oxygen to the heart muscle can clog up. They can clog up with clumps of fat called plaque. Blood cannot flow through clogged arteries. Clogged arteries can cause heart attacks. Exercise is one way to keep your heart healthy. Eating fruits, vegetables, and low-fat meats is another way to keep your heart healthy. You should have regular physical checkups. The main way to keep your heart healthy, however, is not to smoke.
Smoking
Smoking is “hateful to the nose, harmful to the brain, and dangerous to the lungs.” This was the view of England ’s king James I in 1604. For long afterward, smoking was considered harmless. Today, more and more people agree with King James.
TOBACCO AND NICOTINE
Smoking means breathing the smoke of burning tobacco leaves. Tobacco is a plant. Tobacco is processed for smoking in different ways. People smoke tobacco in pipes, cigars, and cigarettes. Tobacco smoke contains about 4,000 chemicals. One of them is nicotine. In large amounts, nicotine is a poison. In small amounts in the human body, nicotine stimulates the nerves. It makes the heart beat faster.
HISTORY
Native Americans smoked tobacco as long as 2,000 years ago. Explorer Christopher Columbus saw them smoking in 1492. His crew brought tobacco to Europe . European sailors spread it around the world. Some people believed then that smoking could cure diseases. By 1600, people smoked mainly for enjoyment. Cigarettes were invented in Europe . They did not become popular until the 1800s. They were expensive because people had to make them by hand. Then a cigarette-rolling machine was invented. In the 1940s, doctors began to notice connections between smoking and lung cancer and other diseases. They began to study the chemicals in cigarette smoke. Many of these chemicals were found to cause cancer. A group of scientists prepared a report for the United States government in 1964. The report declared cigarette smoking to be a serious health danger. Since then, smoking in the United States has greatly declined. Health warnings appear on cigarette packages. Smoking is banned on most airline flights. It is banned from many offices and public places.
SMOKING AND HEALTH
Cancer experts say that cigarettes kill hundreds of thousands of Americans every year. Lung cancer kills more Americans than any other kind of cancer. Smokers are 20 times more likely than nonsmokers to develop lung cancer. Smokers also are at greater risk for other forms of cancer and other lung diseases. Mothers who smoke can injure the health of their babies. Quitting smoking greatly lowers the chances of dying from diseases caused by smoking.
