5 I curricula science exercise 1 page 92.0:01
We can't help it, but we all sneeze, yawn, blush, hiccup up, 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.0:43
So yawning helps you to take more oxygen into the blood.0:52
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.1:07
Yawning is contagious.1:10
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.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 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 six different muscles, including your eyelids, to push air out through your nose at up to 160 kilometres 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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