Chapter 15: Your Everyday Breathing Guards

One Breath, From Beginning to End

Take a slow, gentle breath in. Hold it for just a moment, and then let it go. That breath took only a few seconds, and you probably did not think twice about it. Yet in those few seconds, dozens of guards and helpers inside your body worked together, each doing its own job at exactly the right time. Now that you have met them all, let us follow one single breath on its whole journey, from the air outside to the very tips of your toes and back again.

The journey begins in the air around you. As you learned at the start of this book, air is a mixture of gases. Most of it is nitrogen, and about one fifth of it is the oxygen your body needs. Floating in the air there are also tiny travelers: specks of dust, grains of pollen, bits of soot and, sometimes, germs. Your breath brings in the oxygen you need, and your guards make sure that as few of those unwanted travelers as possible get any farther.

The first gate is your nose. Inside, little hairs catch the bigger specks, and a sticky layer of mucus traps many of the smaller ones. The inside of the nose also warms the air and makes it moist, so that it is gentle on your lungs. Your sense of smell stands guard too, warning you about smoke or spoiled food. If something tickles the inside of your nose, a sneeze may burst out to blast it away. And if something tickles your throat or airways, a cough does the same job, pushing the unwanted thing back out through an emergency exit.

Next, the air passes through the throat, the busy crossroads where the path for air and the path for food meet. At this crossroads stand the tonsils and adenoids, guard posts where germ-fighting cells keep watch and learn about the germs that come by. Just below them waits the epiglottis, the little door that flips down over the windpipe whenever you swallow, so that food and drink go down the right way. When you are not swallowing, the little door stays open, and air flows down into the windpipe.

Then the air travels down the windpipe. The windpipe is lined with mucus and millions of tiny hairs called cilia, which sweep together like an escalator, carrying trapped dust and germs up toward the throat, where they can be swallowed or coughed away. From the bottom of the windpipe, the air flows into the bronchi, the big branches of the breathing tree, and then into smaller and smaller branches called bronchioles, spreading out through both lungs.

At the very end of the smallest branches, the air reaches the alveoli, hundreds of millions of tiny balloons with walls thinner than the thinnest tissue paper. Here, oxygen slips across into the blood, and carbon dioxide slips out of the blood into the air. Living in the alveoli are the macrophages, the faithful cleaners, who gobble up any dust or germs that have made it this far.

Now the oxygen boards the red train. Red blood cells, packed with a red substance called hemoglobin, carry the oxygen to the heart, which pumps it out to every part of your body: your brain, your muscles, your skin, your bones. White blood cells ride along in the blood as well, ready to fight germs wherever they show up. On the way back, the blood carries carbon dioxide to the lungs.

And all of this happens because of the breathing pump. The brainstem keeps the beat. The diaphragm pulls down, and the ribs swing out to draw air in. Then the pump relaxes, and the used air, carrying carbon dioxide, flows back out the way it came. One breath, from beginning to end. And then, a few seconds later, another one begins.

A Day With Your Guards

Your guards are not only busy on special days. They work every hour of every ordinary day. Let us imagine one ordinary day and watch them at work.

In the morning, you wake up and stretch, and you take a big, slow yawn. Your lungs fill with fresh air, and your breathing speeds up a little as you get out of bed and start to move. You splash your face, wash your hands before breakfast, and sit down to eat. Each time you swallow, the epiglottis closes over your windpipe, and each time you breathe, it opens again. You never have to think about it.

On the way to school, the air outside might carry pollen from flowers, dust from the road, or fumes from traffic. Your nose catches much of it, and the escalator in your windpipe carries the rest away. If a speck makes it all the way to the alveoli, a macrophage is waiting to clean it up. If a sneeze comes, you catch it in your elbow, so that your germs do not spray onto your friends.

At school, you sit near many other children. Some of them may have a cold, and their droplets and the things they touch may carry germs. Your guards are on alert. Before lunch, you wash your hands with soap and water, scrubbing between your fingers and around your thumbs. Germs that hitched a ride on your hands go down the drain instead of into your mouth. If a germ does manage to get in, memory cells from earlier fights, or from vaccines, may recognize it and stop it quickly.

After school, you run around outside. Your brainstem notices that your muscles need more oxygen, and your breathing pump speeds up. Your heart beats faster to send the red train racing. Big, deep breaths stretch your lungs open, and your diaphragm and rib muscles get a good workout. When you stop to rest, you puff and pant for a minute, and then your breathing slowly settles down.

In the evening, you eat dinner, drink some water, maybe read a book or talk with your family about your day. Your breathing becomes calm and slow. Your guards keep working quietly in the background, the way the lights in a house stay on while everyone relaxes. Then it is time for bed, and a new shift begins.

Sleep: The Night Shift

When you fall asleep, your body does not switch off. It changes to its night shift. Your breathing becomes slower and more even. The brainstem keeps the beat all night long, so your diaphragm keeps moving air in and out, even while you dream. You do not need to remember to breathe. Your guards remember for you.

Sleep is a time of repair and growth. While you sleep, your body fixes small bits of wear and tear from the day, and your growing body gets on with growing. Your immune system is busy too. Scientists have found that getting enough sleep helps the immune system work well, and that people who sleep too little may catch illnesses more easily.

How much sleep do children need? Most children of elementary school age need somewhere around nine to twelve hours of sleep each night. That may sound like a lot, but your body is doing a great deal of work while you rest. Going to bed at about the same time each night, and keeping bright screens away for a while before bed, can help you fall asleep more easily.

A quiet, airy bedroom helps your night shift too. Fresh air, a comfortable temperature, and a room kept free of smoke make it easier to breathe calmly through the night. If a grown-up ever notices that a child snores loudly every night, seems to stop breathing for a moment during sleep, or always wakes up tired, the grown-up can talk to a doctor about it.

Food and Water: Fuel for the Guards

Your guards need fuel, just as a car needs fuel and a fire needs wood. That fuel comes from the food you eat. Food gives your body energy to breathe, play and think. It also gives your body the building blocks it needs to grow, to repair itself and to make new cells, including new germ-fighting cells and new red blood cells.

No single food has everything your body needs, so the best plan is to eat many different kinds of food. Fruits and vegetables of many colors, grains such as rice or bread, beans, nuts and seeds, eggs, fish, meat or other foods that give you protein all help in different ways. Every family has its own favorite dishes, and there are many healthy ways to eat. Eating a variety of foods is like giving your guards a full toolbox instead of just one tool.

As you read in Chapter 10, your red train needs iron from food to make hemoglobin, the part of red blood cells that carries oxygen. Your skin, your airways and your immune system also need vitamins and minerals from many different foods. You do not need to remember every name. Eating a colorful plate most days is a good way to get what your body needs.

Water matters too. Your body is made up of a lot of water, and you lose some of it every time you breathe out, sweat or go to the toilet. Drinking enough water helps keep the mucus in your nose and airways thin and slippery, so that the escalator of tiny hairs can move it easily. Water is a simple drink that your whole body welcomes, especially after running and playing.

Food is also about more than fuel. Sharing a meal with people you love, trying a new taste, or helping to wash vegetables are happy parts of life. Eating slowly, sitting down and chewing well also helps the epiglottis do its job of keeping food out of your windpipe. Mealtimes can be a calm, cheerful break for your whole body.

Play, Laughter and Calm Breaths

Play is one of the best gifts you can give your lungs. When you chase a ball, climb a frame or swim across a pool, your whole breathing team gets stronger. Being outdoors in fresh air, away from smoke and heavy traffic, is especially good. You do not need a special sport or a gym. Your own two feet and a little open space are enough.

Laughter is good for your breathing too. When you laugh, your diaphragm and belly muscles give quick little pushes, and air rushes in and out in bursts. A good, long laugh can leave you breathing deeply afterward. Singing works your breathing muscles as well, because you have to take in a big breath and let it out slowly to hold a long note.

Your breath can also help you when you feel worried, angry or upset. When people feel scared or cross, they often breathe fast and shallow. Slowing your breathing down can help your body feel calmer. Here is a gentle way to try it: sit comfortably, put one hand on your belly, and breathe in slowly through your nose while you count to about four. Then breathe out slowly through your mouth, a little longer than you breathed in, as if you were blowing gently on a spoonful of warm soup. Do this a few times and notice how you feel.

This slow breathing works because your breath is connected to the parts of your body that control how calm or excited you feel. Long, slow breaths out send a quiet message through your body that it is safe to relax. You can use this trick before a test, before a shot at the doctor's office, when you cannot fall asleep, or any time you need a moment of calm. Your breath is always with you, wherever you go.

Feelings matter to health, and so do the people around you. Talking about your feelings with a grown-up you trust, spending time with friends and family, and getting outside to play all help you feel strong on the inside, just as your guards help you stay strong on the outside.

Being a Guard for Others

Throughout this book, you have seen how your body guards you. But you have also discovered that you can be a guard for other people. Many of the most powerful ways to stop germs depend not just on one body, but on everyone working together.

When you cover a cough or a sneeze with a tissue or your elbow, you keep your droplets from reaching the people around you. When you wash your hands, you remove germs that might otherwise travel to your family and friends. When you stay home to rest while you are sick, you give your own body time to heal and give your classmates a better chance to stay well. When you get the vaccines that a doctor or nurse recommends, you help build the umbrella of community protection that shelters babies, older people and anyone whose guards are not as strong.

You can also help keep the air clean for everyone. Walking or cycling for short trips when it is safe, helping to plant a tree, keeping your home's air fresh, and staying away from smoke are all small choices that add up. Clean air belongs to everybody, and everybody can help look after it.

And you can be a guard simply by speaking up. If a friend is coughing hard or seems to be having trouble breathing, tell a grown-up straight away. If you feel unwell yourself, tell a grown-up how you feel. Grown-ups, doctors and nurses are part of your team, and a grown-up should always talk to a doctor about symptoms that worry them. Asking for help is never a bother. It is one of the wisest things anyone can do.

Thank You, Breathing Guards

Let us take one more look at the amazing team inside you. At the front are the nose with its hairs and mucus, and the sneezes and coughs that throw out intruders. At the crossroads, the tonsils keep watch, and the epiglottis, the little door, keeps food out of the windpipe. Farther down, the windpipe runs its escalator of tiny hairs, the bronchi spread out like the branches of a tree, and hundreds of millions of alveoli fill like tiny balloons while the macrophages sweep and clean. The blood, the red train, carries oxygen everywhere, and the diaphragm and ribs keep pumping, breath after breath. Behind them all, the brainstem never forgets to keep the beat.

When germs slip past all those guards, your body turns up the heat, sends in its germ fighters and remembers the invader for next time. When you help with soap and water, vaccines, clean air, good food, plenty of sleep and lots of play, your guards have everything they need to do their best work.

Your guards are not perfect, and they do not need to be. Everyone catches a cold sometimes, and everyone coughs and sneezes. That is part of having a living, breathing body. What is remarkable is how hard your guards work, how quickly they learn, and how often they keep you safe without your ever knowing.

Almost everything in this book was discovered by curious people who wondered how the body works and kept asking questions. They looked through microscopes, listened to chests, counted breaths and tested their ideas again and again. There is still much more to learn about the lungs, about germs and about keeping the air clean. Perhaps one day you will be one of the people who discovers something new, who helps care for others when they are sick, or who helps protect the air we all share. Keep wondering, and keep asking questions.

From the very first breath you took when you were born, your breathing team has been with you, day and night. It will be with you through every adventure still to come: every race you run, every song you sing, every friend you hug and every quiet night of sleep. You might never see these guards, but now you know they are there.

So the next time you breathe in the cool morning air, blow out the candles on a cake, or take a slow breath to calm down, you can think of the whole team working inside you. Breathe in, breathe out. Thank you, guards. Every breath you take is a small, everyday wonder, and it belongs to you.

Key Words

Respiratory system: All the body parts that work together for breathing, including the nose, throat, windpipe, bronchi, lungs and diaphragm.

Mucus: A sticky, slippery liquid that lines the nose and airways. It traps dust and germs so that they can be carried away.

Cilia: Millions of tiny hairs lining the airways. They sweep mucus and trapped dirt up and out of the lungs like an escalator.

Epiglottis: A small flap at the top of the windpipe that closes when you swallow, so that food and drink go down the right way.

Alveoli: Hundreds of millions of tiny air sacs at the ends of the smallest airways, where oxygen enters the blood and carbon dioxide leaves it.

Macrophage: A white blood cell that lives in the lungs and other parts of the body, gobbling up dust, germs and worn-out cells.

Hemoglobin: The red substance inside red blood cells that carries oxygen from the lungs to the rest of the body.

Diaphragm: A dome-shaped muscle under the lungs. It pulls down to draw air into the lungs and relaxes to let air flow out.

Immune system: The body's whole team of germ fighters, which finds germs, fights them and remembers them for next time.

Oxygen: A gas in the air that every cell in your body needs. Your lungs take it in and your blood carries it everywhere.