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Sonic reflexes

Human Anatomy, Physiology, and Medicine. Anything human!

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Postby ragav.payne » Sun Sep 24, 2006 8:24 am

mith wrote:really? I thought reflexes were from the spine...even a brain dead person would have reflexes.


That's exactly what i'm lacking, some knowledge about biology.

I think we should get back to the basic question which i asked.

"Why do we shout when in sudden physical pain?".

Do you have any explanations to offer?

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Postby pd84 » Sun Sep 24, 2006 9:53 am

From your reaction to the previous poster, I think I have interpreted the question in a different way to what you aimed for.

Perhaps if you do a little research, maybe there is something linked with shouting and the release of brain opiates or something like that. I don't really know for sure, I haven't studied it in detail.
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Postby ragav.payne » Sun Sep 24, 2006 11:53 am

pd84 wrote:From your reaction to the previous poster, I think I have interpreted the question in a different way to what you aimed for.

Perhaps if you do a little research, maybe there is something linked with shouting and the release of brain opiates or something like that. I don't really know for sure, I haven't studied it in detail.



mmmm........A search in the Wikipedia gives no page on "Bain opiates" and it says "opiates" are alkaloids from opium. That's no where close to what i'm looking for.

Can you do me a favour? Think of the best biology expert with whom you can have contact, and give him this page's URL. If you think this is too big a favour....then leave it.

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Postby pd84 » Sun Sep 24, 2006 1:12 pm

We know that a painful stimulus activates a complex afferent system, the organisation and integration centres of which are only now being partly elucidated. We can accept the view of Bard and Mountcastle (1948) according to which the neocortex, the cingulate cortex, the amygdaloid nucleus and the pyriform lobe correspond to zones of the inhibition of pain and anger reactions. Their influence would be transmitted as far down as the brainstem by way of a circuit similar to the amygdaloid pathway. They suggest the presence, in addition, of a direct extra-amygdaloid pathway via which the neocortex might exert a facilitatory influence on the mesencephalic centres.

The mesencephalic structures where the facial and vocal components of the pain reaction are integrated are situated in the central part of the brainstem, within the peri-aqueductal grey matter. Destruction of this area in animals results in complete loss of vocal or expressive reactions following a painful stimulus (Adametz and O'Leary 1959; Kelly et al. 1946), while excitation of this same area provokes intense vocal and facial reactions.

Source: http://sommeil.univ-lyon1.fr/articles/j ... 69/p2.html

Any help?
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Postby ragav.payne » Sun Sep 24, 2006 4:40 pm

pd84 wrote:We know that a painful stimulus activates a complex afferent system, the organisation and integration centres of which are only now being partly elucidated. We can accept the view of Bard and Mountcastle (1948) according to which the neocortex, the cingulate cortex, the amygdaloid nucleus and the pyriform lobe correspond to zones of the inhibition of pain and anger reactions. Their influence would be transmitted as far down as the brainstem by way of a circuit similar to the amygdaloid pathway. They suggest the presence, in addition, of a direct extra-amygdaloid pathway via which the neocortex might exert a facilitatory influence on the mesencephalic centres.


Would be of great help if you can get the translation of the above text in english.

The mesencephalic structures where the facial and vocal components of the pain reaction are integrated are situated in the central part of the brainstem, within the peri-aqueductal grey matter.


Does the term "brainstem" refer to a part of the brain?

Destruction of this area in animals results in complete loss of vocal or expressive reactions following a painful stimulus (Adametz and O'Leary 1959; Kelly et al. 1946), while excitation of this same area provokes intense vocal and facial reactions.

Source: http://sommeil.univ-lyon1.fr/articles/j ... 69/p2.html

Any help?


Would be of great help if it did'nt sound this technical. I'd like it in a simpler language.

meanwhile,I found out this explanation......

"A sudden reflex contraction of many body muscle, especially in the chest and abdomen, produces a high internal pressure. But the reflex contraction also closes the outlet in the throat so air can't escape. But enough pressure or a sudden relaxation in the larynx will cause an outrush of air which activates the vocal cords to produce a grunt or groan or shriek depending on timing."

Not mine though......


But anyway, thanks.
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Postby pd84 » Sun Sep 24, 2006 5:51 pm

Basically, the pain reflex circuit is a complex system. The areas of the brain that are stimulated during this, influence other areas as far down as the brain stem. The brain stem btw is part of the brain - at it's 'base' - and is continuous with the spinal cord.

'Mesencephalic structures' in the central part of the brain stem control the vocal and facial response you display when in pain. This response mechanism will possibly include the contraction of body muscle as you have found out for yourself.

The last bit just illustrates how the role of this pathway can be demonstrated. Destroying the mesencephalic structures leads to no shout with a pain stimulus, while excitation of it brings the opposite.

Don't get too held up by the names of the brain areas. If you want to know about them, just search for them individually, but it's not necessary.
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Postby ragav.payne » Mon Sep 25, 2006 10:40 am

Thank you very much

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Postby canalon » Mon Sep 25, 2006 11:47 pm

Let's make a thought experiment:

You will need:
-yourself, a strong will and determined physicist
-A source of stable and intense heat (barbecue, oven range...)
-a chronometer
-a physician both to record the results and because you might find this handy (even if this is only a Thought experiment, do not actually do that!)

Turn on the heat source to the maximum intensity. Put one finger on it and measure how long you can keep it without letting a sound go. That is were the strong will is important...
Now put another finger on the range for the exact same time, and you are allowed to scream as much as you want.
Which finger will heal first?
If I read you correctly the second finger should heal way better. Somehow I think my imiginary physician may have difficulties to make any differences.

Why? because the nerve impulse signal that carries the burning signal do not transfer anything more than a signal, not directly related to the energy of the stimulus (the signal intensity is constant, its frequency only change with intensity) and do not dissipate any of the energy acquired by the nerve receptor. just like the intensity of the siren in a smoke detector is not related to the quantity of smoke.
No Peltier effect through your nerves... ANd if you use a big enough energy source the nerve signal cannot be sent and the effect will be exactly the same.

This could be repeated with any kind of stimulus (you can test with a hammer on your remaining fingers...)

Good luck.
Patrick

Science has proof without any certainty. Creationists have certainty without
any proof. (Ashley Montague)
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Postby ragav.payne » Wed Sep 27, 2006 2:01 am

I got it......

The energy supplied to our body directly from any external source does'nt add up to the energy already present in our body in the form of glucose. The energy cannot navigate in our body. Instead it is simply used up for the defrormation of the skin cells in contact.

The possible correct explanation would be....

Sensory cells (receptors) in the stimulated body part send signals to the spinal cord along a sensory nerve cell. Within the spine a reflex arc switches the signals straight back to the muscles of the effectors via an intermediate nerve cell and then a motor nerve cell; contraction of the leg occurs, and the muscle contracts (the arm or leg jerks upwards).

While 'screaming' is.....just a kind of involuntary action which can be suppressed by will. The main purpose being communication. The energy released by this action is so trivial that it is almost negligible.

"Then what is the signal made of?" will be the right question to ask.
Possibly some chemical created and sent to the spinal chord by the sensory organs. This chemical's composition, i *guess*, would'nt depend upon the pain stimulus but rather it would contain the information of where the stimulus is acting.


canalon wrote:the signal intensity is constant, its frequency only change with intensity


I don't get this point, do you mean to say that the signal has a waveform?

canalon wrote: just like the intensity of the siren in a smoke detector is not related to the quantity of smoke.


How would this explain the difference in pain perception with the difference in energy transmitted by the stimulus?



canalon wrote:-yourself, a strong will and determined physicist


Nah! i'm just a bad creationist.


Thanks canalon.
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Postby geonyzl » Wed Sep 27, 2006 2:55 am

The energy that is tranfered to your body is a stimulus. Now your body contains millions of neurons to transmit the impulse to your brain and the brain would translate and send back the information for your reaction. Now the level of resistance would depend in each individual.
You have the idea there, but the problem we can't actually quantify it if the energy transfered is the equal amount of energy. But probably you are correct. Because even the person is highly resistant to heat, as the heat increases it will move away immediately or react.


geon :)
If there's a will, there's a way...:)
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