Chapter 5: The Epiglottis: The Little Door That Keeps Food Out

Two Roads and One Little Door

Take a sip of water and swallow it. Easy, right? You probably did not think about it at all. But in that one small swallow, your body did something truly remarkable. It sent the water down the right road and kept it away from the wrong one, all in less time than it takes to blink twice.

In the last chapter, you visited the crossroads in your throat. You learned that air and food both pass through your throat, and that at the bottom, the road splits in two. The front road leads to your lungs. The back road leads to your stomach. Air must go to the lungs, and food and drink must go to the stomach.

If food or drink went into your lungs, it would cause trouble. Your lungs are made for air, not for crumbs or juice. Bits of food in the lungs could block the tiny air passages, and germs riding on the food could cause an illness there. So the body has to keep the two roads apart, again and again, every single day.

One of the most important guards at the split is a small flap called the epiglottis. It sits just behind the base of your tongue, right above the entrance to your breathing tubes. It is shaped a bit like a leaf, with a narrow stem at the bottom and a wider, rounded top. It is made of the same firm but bendy material as the tip of your nose, called cartilage.

Most of the time, the epiglottis stands up straight, like an open door. Air flows past it freely, down into your lungs. But when you swallow, the epiglottis tips down and covers the entrance to your breathing tubes. Then food and drink slide over it and into the road that leads to your stomach. When the swallow is finished, the door swings back up, and air flows in again.

The epiglottis does not work alone. It is part of a whole team of movements that happen every time you swallow. In this chapter, you will meet that team, find out what happens when something goes down the wrong way and learn how you can help your little door do its job well.

Meet the Voice Box

The entrance that the epiglottis covers is the top of your voice box. The real name for the voice box is the larynx. The larynx sits in the front of your neck, at the top of the tube that carries air down to your lungs. It is built from several pieces of cartilage joined together, a little like a small hollow box.

Gently touch the front of your neck, in the middle, partway between your chin and the top of your chest. You may feel a firm bump. That bump is part of the cartilage of your larynx. In grown-ups, and especially in grown-up men, the bump often sticks out more and is easy to see. It grows bigger as children become teenagers, which is one reason why voices get deeper as people grow up.

Inside the larynx are your vocal cords. You met them briefly in Chapter 3, where they helped you cough. The vocal cords are two small folds of tissue that stretch across the inside of the larynx. When you breathe quietly, they stay open, like two curtains pulled apart, so that air can flow through easily.

When you talk, sing or hum, the vocal cords move close together. Air from your lungs pushes between them and makes them shake very quickly. That shaking is called vibration, and it makes the sound of your voice. Your tongue, lips and mouth then shape the sound into words.

Try this. Rest your fingers lightly on the front of your neck and hum a long, gentle note. Can you feel a buzzing under your fingers? That buzzing is your vocal cords vibrating. Now stop humming and just breathe quietly. The buzzing stops, because the vocal cords have opened again.

The vocal cords are not only for making sounds. They are also guards. Because they can close tightly, they act like a second door just below the epiglottis. When you swallow, they shut firmly to help seal the entrance to your lungs. And as you learned in Chapter 3, they close to build up pressure before a cough. So your voice box is a door, a guard and a musical instrument all at once.

Here is another safe thing to notice. Try to hum a long note and then swallow in the middle of it. The hum stops for a moment while you swallow, and then it can start again afterward. That happens because the vocal cords close tightly during the swallow, so no air can pass between them to make a sound. Your body simply does not allow talking and swallowing at the very same instant.

What Happens When You Swallow

Swallowing looks simple, but it is really a beautifully timed set of movements. Many muscles in your mouth, throat and neck work together, each at exactly the right moment. It is a little like a team of dancers who all know their steps perfectly. Let us follow a bite of food through a swallow, one step at a time.

First, you chew the food. Your teeth break it into small pieces, and your saliva makes it soft and wet. Your tongue gathers the chewed food into a small, soft ball. You control this part. You can decide how long to chew and when you are ready to swallow.

Next, your tongue presses up against the roof of your mouth and pushes the soft ball of food backward, toward your throat. As soon as the food reaches the back of your mouth, the rest of the swallow happens automatically. Your brainstem, the part of the brain that controls automatic actions, takes over. From this moment, you could not stop the swallow even if you tried.

Now several things happen almost at the same time. The soft roof at the back of your mouth lifts up and closes off the space behind your nose, so that food cannot go up into your nose. Your larynx moves upward and forward. The epiglottis tips down over the entrance of the larynx. And the vocal cords inside the larynx close tightly.

You can feel one of these steps for yourself. Rest your fingers very lightly on the bump at the front of your neck and swallow your saliva. Did you feel the bump move up and then come back down? That is your larynx rising to tuck itself under the epiglottis and away from the path of the food. It is one of the moves that keeps your breathing tubes safe.

While all of this is happening, your breathing stops for a moment. It is only a very short pause, usually less than a second, so you never notice it. But it is important. With the doors closed and the breathing paused, the food has only one place to go, which is down the back road toward your stomach.

The back road is a muscular tube called the esophagus. The esophagus runs down through your chest, behind your breathing tube, to your stomach. When the food enters the esophagus, the muscles in the walls of the tube squeeze one after another, in a wave. The wave pushes the food down, the way you might squeeze toothpaste along a tube from the bottom to the top.

Because the esophagus pushes food along with muscle waves, food does not need to simply fall down into your stomach. That is why astronauts floating in space, where nothing falls down, can still swallow their food. Their esophagus squeezes the food along to the stomach, just as yours does.

Drinks move through the throat differently from food. A soft, chewed bite of food moves fairly slowly, so the doors in your throat have plenty of time to close. A sip of water or juice is thin and runs very quickly. The doors have to be even faster to keep up with it. That is one reason why a drink goes down the wrong way more often than a well-chewed bite of food does.

As soon as the food has passed into the esophagus, everything returns to normal. The epiglottis tips back up, and the larynx slides back down. The vocal cords open. The soft roof at the back of your mouth drops back into place. And you breathe again. The whole swallow takes only about a second or two.

Breathing and Swallowing Take Turns

You swallow far more often than you might think. You swallow when you eat and drink, of course. But you also swallow your saliva again and again throughout the day, along with the mucus that slides down from your nose. Altogether, a person swallows hundreds of times every day. You even swallow while you sleep, though much less often.

Each of those swallows means a short pause in your breathing. Your body is very good at fitting these pauses in between breaths. Usually, a swallow comes at the end of a breath out, and then you breathe in again right after it. Breathing and swallowing take turns, like two children sharing a swing, so they never get in each other's way.

Here is a safe way to notice this. Sit quietly, breathe normally, and then swallow your saliva. Pay attention to your breathing right at the moment you swallow. You may notice that, just for that instant, you are neither breathing in nor breathing out. Then your breathing carries on as before.

Babies are built a little differently. In a baby, the larynx sits higher up in the neck than it does in an older child or a grown-up. This helps a baby drink milk and breathe in a quick, steady rhythm. As children grow, the larynx slowly moves lower down in the neck.

Scientists think that having the larynx lower in the neck helps people make the wide range of sounds used in speaking and singing. It gives the voice more room to shape sounds. But it also means that the roads for air and food cross each other in the throat. That is why the epiglottis and the other doors are so important for people.

When Something Goes Down the Wrong Way

Your little door works almost perfectly, almost every time. But no guard is perfect. Once in a while, a crumb or a drop of drink slips toward the entrance to your breathing tubes before the doors have closed. People often say that it went down the wrong way.

This is most likely to happen when you are doing two things at once. If you laugh, talk or gasp while you have food or drink in your mouth, you may breathe in at the same moment you are swallowing. Breathing in pulls air, and sometimes a little food or drink, toward the lungs. Eating too fast or taking very big bites can also make it harder for the doors to close in time.

When something goes down the wrong way, your body acts at once. The lining at the entrance to the larynx and the breathing tubes is very sensitive. As soon as it feels a crumb or a drop, it sends an alarm to the brainstem. The brainstem answers with a strong cough. You learned in Chapter 3 how a cough builds up pressure and then blasts air out. That blast usually pushes the crumb or drop right back up and out.

That is why you cough so hard when a drink goes down the wrong way, and why your eyes may water and your face may turn red. It can feel scary for a moment, but the cough is doing exactly what it should. It is guarding your lungs. Usually, after a few strong coughs, the problem is cleared and you can breathe comfortably again.

After a coughing fit like this, your throat may feel tickly or a little sore for a short while. That feeling usually fades soon. But if coughing or an odd feeling in the chest keeps going for a long time after something went down the wrong way, tell a grown-up. The grown-up can decide whether to talk to a doctor about it.

Sometimes, though, a piece of food or a small object gets stuck in the breathing path and blocks the air. This is called choking. A person who is choking badly may not be able to breathe, talk or cough. The person may hold both hands to the throat. Choking is an emergency. If you ever see someone who cannot breathe, talk or cough, shout for a grown-up right away or call for emergency help.

Grown-ups can learn exactly what to do when someone is choking by taking a first aid class. That is a job for trained grown-ups, not for children. Your job, if you ever see someone choking, is to get help as fast as you can. Getting help quickly is a brave and important thing to do.

Helping Your Little Door

The best way to help your epiglottis is to give it time to do its job. The doors in your throat work best when you eat calmly and pay attention to your food. Here are some simple habits that make swallowing safer for everyone, children and grown-ups alike.

Sit down when you eat or drink. Running, jumping or playing with food in your mouth makes it much easier for a bite to slip down the wrong way, because you breathe hard and fast when you move. It is safer to finish your snack first and then go and play.

Take small bites and chew your food well before you swallow. Small, well-chewed pieces are soft and easy for the throat to handle. Big pieces are harder to swallow and are more likely to get stuck. There is no prize for finishing first, so take your time and enjoy the taste of your food.

Try to finish chewing and swallowing before you talk or laugh. Mealtimes are wonderful for sharing stories and jokes, and you do not need to be silent. Just swallow your bite first, and then say what you want to say. Your friends and family will happily wait a moment to hear it.

Some foods are firm, round and smooth, which makes them easier to get stuck in a small throat. Whole grapes, whole nuts and hard sweets are examples. Grown-ups often cut round foods into smaller pieces for young children, and that is a sensible way to keep eating safe. If you have younger brothers, sisters or cousins, you can help by telling a grown-up if you see a little one with something like this in the mouth.

Never put small objects in your mouth, such as coins, marbles, buttons, beads, pen caps or pieces of a burst balloon. These things are not food, and they can get stuck in the throat. Keep small objects away from babies and toddlers too, because little children love to put things in their mouths. If you find a tiny object on the floor, give it to a grown-up.

Beyond the Little Door

Think about how much your little door does for you. Every day, it opens and closes hundreds of times. It lets air flow freely when you breathe and swings shut in an instant when you swallow. It works together with your soft palate, your larynx, your vocal cords and your cough to keep food and drink out of your lungs. And it does all of this without you ever having to think about it.

Now imagine that you are a breath of air. You have come in through the nose, where you were cleaned, warmed and made damp. You have passed through the crossroads of the throat, watched by the tonsils and the adenoids. You have flowed past the open epiglottis and between the open vocal cords. Where do you go next?

Below the larynx, a long tube runs down the middle of your neck and into your chest. This tube is called the windpipe. Its walls are held open by rings of cartilage, so it never squashes flat. And its lining holds one of the most surprising cleaning machines in your whole body.

The inside of the windpipe is covered with millions of tiny hairs, the same kind of cilia that you met in your nose. These cilia sweep sticky mucus, along with any dust and germs caught in it, up and away from your lungs, like a moving staircase carrying everything upward. In the next chapter, you will ride down the windpipe and see how this escalator of tiny hairs keeps your lungs clean.

Key Words

Epiglottis: A small, leaf-shaped flap of cartilage behind the base of the tongue. It tips down to cover the entrance to the breathing tubes each time you swallow.

Larynx: The real name for the voice box. It sits at the top of the windpipe in the front of your neck and holds the vocal cords.

Vocal cords: Two small folds of tissue inside the larynx. They vibrate to make your voice and close tightly to protect your lungs.

Vibration: A very fast shaking movement. When the vocal cords vibrate, they make the sound of your voice.

Swallowing: The set of movements that carries food and drink from your mouth, through your throat and into the esophagus.

Soft palate: The soft back part of the roof of your mouth. It lifts during swallowing to stop food from going up into your nose.

Esophagus: The muscular tube that carries food and drink from your throat down to your stomach. It pushes food along with waves of squeezing.

Choking: When food or an object gets stuck and blocks the breathing path, so air cannot get through. Choking is an emergency, and a grown-up must be called right away.

Windpipe: The tube that carries air from the larynx down into your chest toward the lungs. Its real name is the trachea.