5i Curricula Science.0:00
We can't help it, but we all sneeze, yawn, blush, hiccup, sneeze, cough, or even snore from time to time.0:27
But what exactly is going on in our bodies when we do all these things?0:36
No one knows for sure why we yawn, but one theory is that when you're tired or bored, you don't breathe as deeply as usual, so yawning helps you to take more oxygen into the blood.0:43
Other scientists say that yawning stretches the muscles and lungs and increases the heart rate, helping us to stay more alert.0:57
Most people seem to agree about one thing, though: yawning is contagious.1:07
Even animals and unborn babies yawn.1:13
A cough is an important way of clearing your airways, throat, and lungs of irritations.1:20
When you cough, you breathe in and close your vocal cords.1:27
As you release the air, you make a barking noise—a cough.1:32
It's no secret that we blush when we're embarrassed.1:40
Well, when you feel self-conscious, your body releases adrenaline, which increases the blood flow to your face.1:46
You only blush when you become aware of other people's thoughts and feelings.1:57
We get hiccups when something irritates the diaphragm muscle below the lungs that helps pull air into them.2:07
When we eat or drink too much, or when we feel nervous or excited, the diaphragm pulls down air in a jerky way.2:17
When this air meets your voice box, you make a hiccup sound.2:26
When something such as dust, pollen, or a virus irritates the inside of our nose, a message goes to the brain.2:33
The brain then tells 6 different muscles, including your eyelids, to push air out through your nose at up to 160 kilometers per hour.2:43
When you are asleep and air can't move freely through your mouth or nose, parts of your mouth and throat vibrate and cause snoring.2:57
Reasons why the air can't get through might include an allergy, a cold, or being overweight.3:09
Studies say that about 45% of men and 30% of women snore regularly.3:17
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