*Cough!* *Cough!* Oh no! Do you have a bad cold coming on? We hope not! It's no fun to have a cough. From schoolwork to sleep, coughing can be a distracting burden that no one likes to deal with.

As human beings, we all cough from time to time. Sometimes it might be the result of food or drink going down the wrong pipe. At other times, a persistent cough might be the primary symptom of an illness. So what's going on here?

Coughing is actually a good thing. It shows that your body is working hard to protect you. Coughing is the body's natural way of clearing your breathing passages of unwanted or dangerous irritants.

Although everyone knows what coughing is, scientists define the act as the sudden expulsion of air from the lungs through the epiglottis. How sudden? Very sudden! Some scientists have estimated that coughing expels air from the lungs at the rate of about 100 miles per hour!

What does it take to expel air from your lungs at around 100 miles per hour? As it turns out, it requires multiple events to take place in a particular sequence. First, your vocal cords must open widely to allow extra air to pass into your lungs.

Once your lungs are filled with air, your epiglottis closes off your windpipe (called the larynx) while your rib and stomach muscles simultaneously contract to increase the amount of pressure behind your epiglottis. The increased pressure opens the epiglottis so that the air is expelled with great force.

If these things happen and all goes well, whatever irritant caused the cough will be dislodged by the air rushing through your breathing passageways. Of course, some irritants won't be dislodged so easily, which is why you sometimes have to cough multiple times to return your breathing to normal.

There are many different types of irritants that can trigger coughing. The most common triggers are cold and flu viruses. The mucous caused by such viruses can build up in your breathing passageways, leading to coughing up dislodged mucous.

If you have allergies or asthma, irritants, such as pollen and molds, can trigger coughing. Even for those who aren't allergic to many things, breathing in certain things like cold air, cigarette smoke, and perfumes can cause coughing.

Even though coughing helps to clear your breathing passages so you can breathe easier, it can still be annoying and sometimes painful. The best way to stop or avoid a cough is to avoid the things that trigger coughing. Once coughing starts, though, there are a variety of liquid cough medicines and cough drops that can help. If a cough persists even with medicine, you should probably go see a doctor.

Wonder What's Next?

Tomorrow's Wonder of the Day will take you from deep underground to your shower head!