Has anyone got any views on this? Just why do we do it?

What is currently taught at Medical Schhol is that when we breathe at rest, not all of our lungs get inflated, namely the bottom of them. This causes the Alveoli to partially collapse, so the Brain sends a trigger to make us yawn and inflate the Lungs fully.

This is however contradicted by fetus's that have been observed yawning in the womb??

Whadaya reckon?

I did a-level biology years ago and the teacher told us it was to send a large supply of oxygen to the brain to wake you up, hence why you yawn when your tired. If your at med school though my teachers opinion seems a little daft in comparison.

Chris.

try here too (http://www.sheffieldforum.co.uk/showthread.php?s=&threadid=7639&highlight=yawning)

Search option is an amazing invention :rolleyes:

Moon

Everyone yawns - babies, kids, teenagers, adults. Some birds, reptiles and most mammals also yawn. However, the reason why we yawn is a bit of a mystery. There is also very little research on yawning because for most people yawning is not a problem. Here are a few things that are known about yawns: The average duration of a yawn is about 6 seconds.
In humans, the earliest occurrence of a yawn happens at about 11 weeks after conception - that's BEFORE the baby is born!
Yawns become contagious to people between the first and second years of life.
A part of the brain that plays an important role in yawning is the hypothalamus. Research has shown that some neurotransmitters (for example, dopamine, excitatory amino acids, nitric oxide) and neuropeptides increase yawning if injected in the hypothalamus of animals. so there ya go, still doesnt explain it but thought it was interestin.
also perhaps yawning is like stretching. Yawning and stretching increase blood pressure and heart rate and also flex muscles and joints. Evidence that yawning and stretching may be related comes from the observation that if you try to stifle or prevent a yawn by clenching your jaws shut, the yawn is somewhat "unsatisfying." For some reason, the stretching of jaw and face muscles is necessary for a good yawn.mimi

Originally posted by johnjo
Has anyone got any views on this? Just why do we do it?

What is currently taught at Medical Schhol is that when we breathe at rest, not all of our lungs get inflated, namely the bottom of them. This causes the Alveoli to partially collapse, so the Brain sends a trigger to make us yawn and inflate the Lungs fully.

This is however contradicted by fetus's that have been observed yawning in the womb??

Whadaya reckon?

I always understood that we yawn because our blood needs more oxygen from the lungs, so, we fill our lungs through yawning.

An interesting fact is that we can make others yawn by doing it in front of them, I know because iv'e tried it!!!

Originally posted by halevan
An interesting fact is that we can make others yawn by doing it in front of them, I know because iv'e tried it!!!

So true, but why is that?! Not as if coughing or sneezing has the same effect on others, but then sneezing in front of someone is quite rude I suppose :)

That's exactly what happened to me outside the pub last Saturday night. I came over all tired, yawned and promptly fell asleep - the pavement sufficing for a makeshift bed until the ambulance arrived.

Just reading tis thread has made me yawn, and I don't mean it was boring :)

There is something very satisfying about a yawn, and a stretch, and a sneeze.

I guess that means they are all good for us.