Respiratory system – Hệ Hô Hấp
A Look Inside the Lungs
At the bottom of the trachea (say: TRAY-kee-uh), or windpipe, there are two large tubes. These tubes are called the main stem bronchi(say: BRONG-kye), and one heads left into the left lung, while the other heads right into the right lung.
Each main stem bronchus (say: BRONG-kuss) — the name for just one of the bronchi — then branches off into tubes, or bronchi, that get smaller and even smaller still, like branches on a big tree. The tiniest tubes are called bronchioles (say: BRONG-kee-oles), and there are about 30,000 of them in each lung. Each bronchiole is about the same thickness as a hair.
At the end of each bronchiole is a special area that leads into clumps of teeny tiny air sacs called alveoli (say: al-VEE-oh-lie). There are about 600 million alveoli in your lungs and if you stretched them out, they would cover an entire tennis court. Now that’s a load of alveoli! Each alveolus (say: al-VEE-oh-luss) — what we call just one of the alveoli — has a mesh-like covering of very small blood vessels called capillaries (say: CAP-ill-er-ees). These capillaries are so tiny that the cells in your blood need to line up single file just to march through them.
As you breathe in, your diaphragm contracts and flattens out. This allows it to move down, so your lungs have more room to grow larger as they fill up with air. “Move over, diaphragm, I’m filling up!” is what your lungs would say. And the diaphragm isn’t the only part that gives your lungs the room they need. Your rib muscles also lift the ribs up and outward to give the lungs more space.
At the same time, you inhale air through your mouth and nose, and the air heads down your trachea, or windpipe. On the way down the windpipe, tiny hairs called cilia (say: SILL-ee-uh) move gently to keep mucus and dirt out of the lungs. The air then goes through the series of branches in your lungs, through the bronchi and the bronchioles.
When it’s time to exhale (breathe out), everything happens in reverse: Now it’s the diaphragm’s turn to say, “Move it!” Your diaphragm relaxes and moves up, pushing air out of the lungs. Your rib muscles become relaxed, and your ribs move in again, creating a smaller space in your chest.
By now your cells have used the oxygen they need, and your blood is carrying carbon dioxide and other wastes that must leave your body. The blood comes back through the capillaries and the wastes enter the alveoli. Then you breathe them out in the reverse order of how they came in — the air goes through the bronchioles, out the bronchi, out the trachea, and finally out through your mouth and nose.
Thank You, Alveoli!
The air finally ends up in the 600 million alveoli. As these millions of alveoli fill up with air, the lungs get bigger. Remember that experiment where you felt your lungs get larger? Well, you were really feeling the power of those awesome alveoli!
It’s the alveoli that allow oxygen from the air to pass into your blood. All the cells in the body need oxygen every minute of the day. Oxygen passes through the walls of each alveolus into the tiny capillaries that surround it. The oxygen enters the blood in the tiny capillaries, hitching a ride on red blood cells and traveling through layers of blood vessels to the heart. The heart then sends the oxygenated (filled with oxygen) blood out to all the cells in the body.
Love Your Lungs
Your lungs are amazing. They allow you to breathe, talk to your friend, shout at a game, sing, laugh, cry, and more! And speaking of a game, your lungs even work with your brain to help you inhale and exhale a larger amount of air at a more rapid rate when you’re running a mile — all without you even thinking about it once.
Keeping your lungs looking and feeling healthy is a smart idea, and the best way to keep your lungs pink and healthy is not to smoke. Smoking isn’t good for any part of your body, and your lungs especially hate it. Cigarette smoke damages the cilia in the trachea so they can no longer move to keep dirt and other substances out of the lungs. Your alveoli get hurt too, because the chemicals in cigarette smoke can cause the walls of the delicate alveoli to break down, making it much harder to breathe.
Finally, cigarette smoke can damage the cells of the lungs so much that the healthy cells go away, only to be replaced by cancer cells. Lungs are normally tough and strong, but when it comes to cigarettes, they can be hurt easily — and it’s often very difficult or impossible to make them better. If you need to work with chemicals in an art or shop class, be sure to wear a protective mask to keep chemical fumes from entering your lungs.
You can also show your love for your lungs by exercising! Exercise is good for every part of your body, and especially for your lungs and heart. When you take part in vigorous exercise (like biking, running, or swimming, for example), your lungs require more air to give your cells the extra oxygen they need. As you breathe more deeply and take in more air, your lungs become stronger and better at supplying your body with the air it needs to succeed. Keep your lungs healthy and they will thank you for life!