Yawwwwwn

[Queso]

So what is a yawn?

and why is it contageous?

i used to think it had something to do with the pressure in the air...until i noticed it's contageous over the phone 3,000 miles apart.. :)

[Tormod]

That's a very good question. I saw a documentary on Discovery Channel about that...how mammals yawn and how it is contageous...it said that it has social functions as well as physical functions but as for *why* we yawn I am not sure. :)

[infamous]

That's a very good question. I saw a documentary on Discovery Channel about that...how mammals yawn and how it is contageous...it said that it has social functions as well as physical functions but as for *why* we yawn I am not sure. :)

Tormod; I believe that the yawn response is brought on by the body's need to increase the oxygen level in the blood. I don't remember where or how I came across this information, but it was a reliable source. As for why it seems to be contageous, for that I have no answer other than it may have something to do with mental suggestion.

[Biochemist]

Tormod; I believe that the yawn response is brought on by the body's need to increase the oxygen level in the blood. I don't remember where or how I came across this information, but it was a reliable source. As for why it seems to be contageous, for that I have no answer other than it may have something to do with mental suggestion.

Clearly, this is an innate compulsion for mammals to share views of there respective infundibulae.

 

This was the neanderthal progenitor of "if you show me yours, I will show you mine."

[C1ay]

Tormod; I believe that the yawn response is brought on by the body's need to increase the oxygen level in the blood.

 

This article supports that claim...

[infamous]

Clearly, this is an innate compulsion for mammals to share views of there respective infundibulae.

 

This was the neanderthal progenitor of "if you show me yours, I will show you mine."

 

Really?? thats a good one. Haven't heard about that view yet, although this does seem quite possible when you think about it!!

[Biochemist]

This article supports that claim...

The intriguing part of this is the contagion of it. Humans, at times, seem to odd. Coughs (the non-infections sort) also appear socially contagious. You know, the single cough during a quiet moment in a live play that precipititates another dozen coughs.

 

Fortunately, this does not appear to apply to farts.

[Queso]

this is all really cool stuff. :)

[TeleMad]

One reason we yawm is to equalize pressure. Our outer ear has an external auditory meatus - that's the tunnel that leads into your ear where you have to clean earwax out of. The external auditory meatus terminates at the tympanic membrane (eardrum). On the other side of the tympanic membrane is the middle ear, or tympanic cavity. The pressure in the tympanic cavity is not necessarily the same as the atmospheric pressure in the external auditory meatus. This can cause a reduction in hearing, or if the difference is large enough, pain. The tympanic cavity has a tube, called the Eustachian tube, that runs down to the pharynx (I believe into the nasopharynx, but it might be the oropharynx instead). When we yawn, air 'inflates' the tube and allows air to pass up into the tympanic cavity, equalizing its pressure with atmospheric pressure.

 

This is why people are advised to yawn when climbing or descending in planes.

 

 

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PS: Looked up the anatomy of the ear in my A&P text and found 2 things.

 

First, it is the nasopharynx that the Eustachian tube connects to.

 

Second, I see no mention of the Eustachain tube being "deflated" and yawning causing it to "inflate". I'm pretty sure my professor said that though, and she has been correct on other things she's stated but weren't in the book (but she's also been wrong about a thing or two).

 

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PPS: Looks like my professor was right.

 

”Pressurization of the middle ear can and should be vigorous on the surface [as opposed to during a dive], when no negative pressure gradient is present across the middle ear. This means that it is possible (and desirable) for an individual to pre-pressurize the middle ear and to inflate the Eustachian tube prior to descent.” (http://faculty.washington.edu/ekay/MEbaro.html)

[TeleMad]

I believe that the yawn response is brought on by the body's need to increase the oxygen level in the blood.

 

This article supports that claim...

 

Actually, it contradicts that idea:

 

A long-standing theory behind yawning is that yawning is caused by an excess of carbon dioxide and lack of oxygen in the blood. The brain stem detects this and triggers the yawn reflex. The mouth stretches wide and the lungs inhale deeply, bringing oxygen into the lungs and thence to the bloodstream. It is almost certain however, that this hypothesis is not correct;

[Biochemist]

Actually, I think all of the hypotheses are incorrect. The hoypxic driver is posssible, but unlikely. It is very difficult to establish a base for homeostatic status before a yawn, because one would have to take a measure at precisely the correct time, when there is no indication (yet) that a yawn is going to occur. Further, if we induce hypoxia, we rarely induce yawns.

 

It is certainly true that yawning equalizes the pressure with the middle ear via the eustachian tube, but for most folks, this is an intentional response, not an automatism. That why, for example, few folks yawn on descent in an airplane unless they are told to do so. Babies usually need assistance (like a bottle) to equalize ear pressure on a flight because they do not yawn.

 

Am I am certainly glad the combination of low external pressure and social contagion doesn't drive the fart reaction. Imagine final approach to the runway if THAT were true.

[Queso]

same joke, different context, same thread. biochemist i have to give you reputation for this attempt. :)

[TeleMad]

Actually, I think all of the hypotheses are incorrect.

 

No you don't. You even admitted that what I said was correct. I said:

 

One reason we yawm is to equalize pressure. … The pressure in the tympanic cavity is not necessarily the same as the atmospheric pressure in the external auditory meatus. … The tympanic cavity has a tube, called the Eustachian tube, that runs down to the [nasopharynx] … When we yawn, air 'inflates' the tube and allows air to pass up into the tympanic cavity, equalizing its pressure with atmospheric pressure.

 

And you said:

 

Biochemist: It is certainly true that yawning equalizes the pressure with the middle ear via the eustachian tube...

 

I neither said nor implied that equalizing pressure between the tympanic cavity and external auditory meatus is the reason that yawning is contagious. I merely said that equalizing pressure is one reason we yawn, which is correct, as even you confirmed.