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| RichD |
 Posted: Mon Dec 11, 2006 9:06 pm |
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Guest
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We feel hot and cold, but from a physics viewpoint,
do we really sense temperature, or do we actually
sense the flow of heat to/from the body?
I'm thinking about the skin surface, but I suppose the
question could pertain to any point in the body.
--
Rich |
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| Randy Poe |
| Posted: Mon Dec 11, 2006 9:27 pm |
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RichD wrote:
[quote:b57cf07bf4]We feel hot and cold, but from a physics viewpoint,
do we really sense temperature, or do we actually
sense the flow of heat to/from the body?
I'm thinking about the skin surface, but I suppose the
question could pertain to any point in the body.
[/quote:b57cf07bf4]
I'd say heat flow, which is why "room-temperature" air
feels warmer than water of the same temperature, and
why metals feel cold.
- Randy |
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| Sorcerer |
| Posted: Mon Dec 11, 2006 11:09 pm |
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"RichD" <r_delaney2001@yahoo.com> wrote in message news:1165878399.435714.197260@n67g2000cwd.googlegroups.com...
| We feel hot and cold, but from a physics viewpoint,
| do we really sense temperature, or do we actually
| sense the flow of heat to/from the body?
There is a well known experiment that will prove it to
you. Take three bowls of water, the middle one tepid,
the right as hot as you can stand it and the one on the left
with ice cubes. Place your hands in the cold and hot
bowls for a couple of minutes, then place both in the tepid
water. The tepid water will feel warm to your left hand
and cool to your right hand, thus proving we detect
change rather than absolute temperature.
| I'm thinking about the skin surface, but I suppose the
| question could pertain to any point in the body.
I don't want to try any experiment which invades my body,
scalding hot drinks are not pleasant. You can try it if you
want to, I'm not recommending it. Swallow some iced water. |
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| Richard Schultz |
| Posted: Tue Dec 12, 2006 3:23 am |
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In sci.chem RichD <r_delaney2001@yahoo.com> wrote:
: We feel hot and cold, but from a physics viewpoint,
: do we really sense temperature, or do we actually
: sense the flow of heat to/from the body?
Touch a piece of wood and then a piece of copper. Since they are both
presumably at room temperature, if one feels colder than the other, then
you are sensing heat flow; if they feel the same temperature, then you
are sensing the temperature.
-----
Richard Schultz schultr@mail.biu.ac.il
Department of Chemistry, Bar-Ilan University, Ramat-Gan, Israel
Opinions expressed are mine alone, and not those of Bar-Ilan University
-----
"an optimist is a guy/ that has never had/ much experience" |
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| Martin Hogbin |
| Posted: Tue Dec 12, 2006 7:37 am |
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"RichD" <r_delaney2001@yahoo.com> wrote in message news:1165878399.435714.197260@n67g2000cwd.googlegroups.com...
[quote:45bc99b3bc]We feel hot and cold, but from a physics viewpoint,
do we really sense temperature, or do we actually
sense the flow of heat to/from the body?
I'm thinking about the skin surface, but I suppose the
question could pertain to any point in the body.
[/quote:45bc99b3bc]
This more a question of physiology than physics, but
mostly we seem to detect changes rather than absolutes.
I suspect our nerves respond mainly to temperature
change.
Martin Hogbin |
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| john.spevacek@aspenresear |
| Posted: Tue Dec 12, 2006 11:16 am |
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Martin Hogbin wrote:
[quote:0d469a782a]"RichD" <r_delaney2001@yahoo.com> wrote in message news:1165878399.435714.197260@n67g2000cwd.googlegroups.com...
We feel hot and cold, but from a physics viewpoint,
do we really sense temperature, or do we actually
sense the flow of heat to/from the body?
I'm thinking about the skin surface, but I suppose the
question could pertain to any point in the body.
This more a question of physiology than physics, but
mostly we seem to detect changes rather than absolutes.
I suspect our nerves respond mainly to temperature
change.
[/quote:0d469a782a]
It's a tricky subject. Being an employee of a company that is owned by
a window manufacturer, we are well aware that the likelihood of
replacing your windows increases with distance from the equator. Why?
Because people never complain about a warm draft. A window that leaks
in air 20 degrees below RT will be replaced more quickly than one that
lets in air 20 degrees above RT. Just a quirk with human beings.
John
Aspen Research, - www.aspenresearch.com
"Turning Questions into Answers"
Opinions expressed herein are my own and may not represent those of my
employer. |
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| Mark & Steven Bornfeld |
| Posted: Tue Dec 12, 2006 2:35 pm |
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Guest
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Richard Schultz wrote:
[quote:09ba5c8b6a]In sci.chem RichD <r_delaney2001@yahoo.com> wrote:
: We feel hot and cold, but from a physics viewpoint,
: do we really sense temperature, or do we actually
: sense the flow of heat to/from the body?
Touch a piece of wood and then a piece of copper. Since they are both
presumably at room temperature, if one feels colder than the other, then
you are sensing heat flow; if they feel the same temperature, then you
are sensing the temperature.
[/quote:09ba5c8b6a]
I think it's clear that heat flow stimulates the temperature-sensitive
nerve endings. Apparently though there are specialized nerve endings
specifically stimulated by decrease in temperature (cold receptors) and
those that respond to increase in temperature (heat receptors):
http://ergo.human.cornell.edu/studentdownloads/DEA350notes/Thermal/thsensnotes.html
Steve
[quote:09ba5c8b6a]
-----
Richard Schultz schultr@mail.biu.ac.il
Department of Chemistry, Bar-Ilan University, Ramat-Gan, Israel
Opinions expressed are mine alone, and not those of Bar-Ilan University
-----
"an optimist is a guy/ that has never had/ much experience"
[/quote:09ba5c8b6a]
--
Mark & Steven Bornfeld DDS
http://www.dentaltwins.com
Brooklyn, NY
718-258-5001 |
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| werty |
| Posted: Tue Dec 12, 2006 3:40 pm |
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Guest
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Many senses are relative . The sensors in your face read heat flow ,
But they can continously read temp over a small range .
But maybe the sensor must change to a different body sensor .
Your face will have difficulty reading out in Fahrenhiet , it must
take a "flow" thru its sensors and relate this in a complicated way
in the brain , such as see the snow outside .
Every time i go out in the snow , first my face sensors fail for
the heat
flow thru the face sensors is too much ,
face sensors are overloaded , so the circulation
goes down , and they are what tell the brain , its too cold .
Same with eating food . If its a delicate flavor , tongue sensors (
Sour , etc )
can accurately read the flavor ,
but some flavors ( Temperaturs , as above ) need the mind to
imagine it
( which can lack accuracy ) , using smell !
Thus the human temp' sensing , is using mostly relative sensors
and
combining the results in the mind , , to do amasing difficult task .
The left cerebral cortex is useless in this respect . It has
difficulty making
value judgements ,
except as in a math formula , being "correct" ( read popular )
Its the R side that holds our intellegence , the ability to chain
images
together with strong value judgmenents , at each connection .
The L side is slaved to R side , it serves up small , unargueable
tidbits such as 2 times 65 is 130 .. It refuses to make value
judgements
for it lacks any methods to "hold" those value judgments .
It is wired completely different ,
Grey matter chains R much shorter chain before they connect to
white matter
..
Medical science has proven , no female has ever had a thick
R side (intellegence is a limit , a ratio ) .
Every female ever born has a limit in the R side .
In Astrology , the min requirements for a chance at intellegence
is mercury far from sun . You will need at least 8 degrees .
I have studied people , every Luddite* , i know , has mercury
closer to the sun than 4 degrees .
* General Ned Ludd , circa 1810 , Trade unionist , assasin , arson'
thought productivity was subjective ... The King hung 84 of his
pawns
in 1815 ? |
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| werty |
| Posted: Tue Dec 12, 2006 3:40 pm |
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Guest
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Many senses are relative . The sensors in your face read heat flow ,
But they can continously read temp over a small range .
But maybe the sensor must change to a different body sensor .
Your face will have difficulty reading out in Fahrenhiet , it must
take a "flow" thru its sensors and relate this in a complicated way
in the brain , such as see the snow outside .
Every time i go out in the snow , first my face sensors fail for
the heat
flow thru the face sensors is too much ,
face sensors are overloaded , so the circulation
goes down , and they are what tell the brain , its too cold .
Same with eating food . If its a delicate flavor , tongue sensors (
Sour , etc )
can accurately read the flavor ,
but some flavors ( Temperaturs , as above ) need the mind to
imagine it
( which can lack accuracy ) , using smell !
Thus the human temp' sensing , is using mostly relative sensors
and
combining the results in the mind , , to do amasing difficult task .
The left cerebral cortex is useless in this respect . It has
difficulty making
value judgements ,
except as in a math formula , being "correct" ( read popular )
Its the R side that holds our intellegence , the ability to chain
images
together with strong value judgmenents , at each connection .
The L side is slaved to R side , it serves up small , unargueable
tidbits such as 2 times 65 is 130 .. It refuses to make value
judgements
for it lacks any methods to "hold" those value judgments .
It is wired completely different ,
Grey matter chains R much shorter chain before they connect to
white matter
..
Medical science has proven , no female has ever had a thick
R side (intellegence is a limit , a ratio ) .
Every female ever born has a limit in the R side .
In Astrology , the min requirements for a chance at intellegence
is mercury far from sun . You will need at least 8 degrees .
I have studied people , every Luddite* , i know , has mercury
closer to the sun than 4 degrees .
* General Ned Ludd , circa 1810 , Trade unionist , assasin , arson'
thought productivity was subjective ... The King hung 84 of his
pawns
in 1815 ? |
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| werty |
| Posted: Tue Dec 12, 2006 3:40 pm |
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Guest
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Many senses are relative . The sensors in your face read heat flow ,
But they can continously read temp over a small range .
But maybe the sensor must change to a different body sensor .
Your face will have difficulty reading out in Fahrenhiet , it must
take a "flow" thru its sensors and relate this in a complicated way
in the brain , such as see the snow outside .
Every time i go out in the snow , first my face sensors fail for
the heat
flow thru the face sensors is too much ,
face sensors are overloaded , so the circulation
goes down , and they are what tell the brain , its too cold .
Same with eating food . If its a delicate flavor , tongue sensors (
Sour , etc )
can accurately read the flavor ,
but some flavors ( Temperaturs , as above ) need the mind to
imagine it
( which can lack accuracy ) , using smell !
Thus the human temp' sensing , is using mostly relative sensors
and
combining the results in the mind , , to do amasing difficult task .
The left cerebral cortex is useless in this respect . It has
difficulty making
value judgements ,
except as in a math formula , being "correct" ( read popular )
Its the R side that holds our intellegence , the ability to chain
images
together with strong value judgmenents , at each connection .
The L side is slaved to R side , it serves up small , unargueable
tidbits such as 2 times 65 is 130 .. It refuses to make value
judgements
for it lacks any methods to "hold" those value judgments .
It is wired completely different ,
Grey matter chains R much shorter chain before they connect to
white matter
..
Medical science has proven , no female has ever had a thick
R side (intellegence is a limit , a ratio ) .
Every female ever born has a limit in the R side .
In Astrology , the min requirements for a chance at intellegence
is mercury far from sun . You will need at least 8 degrees .
I have studied people , every Luddite* , i know , has mercury
closer to the sun than 4 degrees .
* General Ned Ludd , circa 1810 , Trade unionist , assasin , arson'
thought productivity was subjective ... The King hung 84 of his
pawns
in 1815 ? |
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| Andy Resnick |
| Posted: Tue Dec 12, 2006 5:11 pm |
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Guest
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RichD wrote:
[quote:d1c22e7916]We feel hot and cold, but from a physics viewpoint,
do we really sense temperature, or do we actually
sense the flow of heat to/from the body?
I'm thinking about the skin surface, but I suppose the
question could pertain to any point in the body.
[/quote:d1c22e7916]
I'd have to do some searching to get the most up-to-date references, but
the skin has specialized nerves that sense temperature. That is, both
an action potential and the number of impulses per second are modulated
in response to temeprature. Furthermore, there are nerves that sense
cold and nerves that sense hot, just as difference taste buds (also
nerves, in lower organisms) sense different molecules.
The location of 'hot' and 'cold' nerves vary in depth- which makes sense
given the high thermal gradient in skin. And these are linked into the
pain receptor system at a higher level of organization.
At a subcellular level, there are channels that transduce mechanical
signals into biological effects- TRP (Transient Receptor Potential)
channels are a major class, and TRPV1 is a known thermally activated
channel. I imagine work is underway to elucidate the configurational
changes that occur.
--
Andrew Resnick, Ph.D.
Department of Physiology and Biophysics
Case Western Reserve University |
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| Randy Poe |
| Posted: Tue Dec 12, 2006 5:26 pm |
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Andy Resnick wrote:
[quote:cbd684979a]RichD wrote:
We feel hot and cold, but from a physics viewpoint,
do we really sense temperature, or do we actually
sense the flow of heat to/from the body?
I'm thinking about the skin surface, but I suppose the
question could pertain to any point in the body.
I'd have to do some searching to get the most up-to-date references, but
the skin has specialized nerves that sense temperature. That is, both
an action potential and the number of impulses per second are modulated
in response to temeprature. Furthermore, there are nerves that sense
cold and nerves that sense hot, just as difference taste buds (also
nerves, in lower organisms) sense different molecules.
The location of 'hot' and 'cold' nerves vary in depth- which makes sense
given the high thermal gradient in skin. And these are linked into the
pain receptor system at a higher level of organization.
At a subcellular level, there are channels that transduce mechanical
signals into biological effects- TRP (Transient Receptor Potential)
channels are a major class, and TRPV1 is a known thermally activated
channel. I imagine work is underway to elucidate the configurational
changes that occur.
[/quote:cbd684979a]
Confirming what you wrote, I just found a reference to a
TRPV receptor (TRPV3), which like TRPV1 is a heat-sensitive
ion channel in skin cells.
http://www.azomed.com/?id=8180
And as you said, there is at least one cold-specific channel
http://www.innovations-report.de/html/berichte/biowissenschaften_chemie/bericht-7627.html
It is called CMR1, for cold and menthol-sensitive receptor,
since menthol was used for some of the experiments rather than
temperature. To these receptors, menthol literally feels
cold, so one answer to OPs question is that sometimes a
sensation of heat or cold is purely chemical and has nothing
to do with temperature or heat flow.
Fascinating subject that is apparently an area of active
research.
- Randy |
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| RichD |
| Posted: Tue Dec 12, 2006 5:35 pm |
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Sorcerer wrote:
[quote:bb1b3cac65]| We feel hot and cold, but from a physics viewpoint,
| do we really sense temperature, or do we actually
| sense the flow of heat to/from the body?
There is a well known experiment that will prove it to
you. Take three bowls of water, the middle one tepid,
the right as hot as you can stand it and the one on the left
with ice cubes. Place your hands in the cold and hot
bowls for a couple of minutes, then place both in the tepid
water. The tepid water will feel warm to your left hand
and cool to your right hand, thus proving we detect
change rather than absolute temperature.
[/quote:bb1b3cac65]
I tried this, and confirm.
It seems a strong argument in favor of heat flow;
or temperature differential, anyway.
--
Rich |
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| RichD |
| Posted: Tue Dec 12, 2006 5:42 pm |
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Guest
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Randy Poe wrote:
[quote:b0d7b298be]We feel hot and cold, but from a physics viewpoint,
do we really sense temperature, or do we actually
sense the flow of heat to/from the body?
I'm thinking about the skin surface, but I suppose the
question could pertain to any point in the body.
I'd say heat flow, which is why "room-temperature" air
feels warmer than water of the same temperature, and
why metals feel cold.
[/quote:b0d7b298be]
Yes, that was my motivation. We had turned off the
heat, then I got out of bed yesterday, and plunked
my bottom down on the toilet seat. Yikes! Nothing
worse than frigid buns in the morn... and I thought,
isn't everything in the room at the same temperature?
So then I decided to drop a note to this board.
--
Rich |
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| Sorcerer |
| Posted: Tue Dec 12, 2006 8:08 pm |
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Guest
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"RichD" <r_delaney2001@yahoo.com> wrote in message news:1165952144.358836.229030@73g2000cwn.googlegroups.com...
| Sorcerer wrote:
| > | We feel hot and cold, but from a physics viewpoint,
| > | do we really sense temperature, or do we actually
| > | sense the flow of heat to/from the body?
| >
| > There is a well known experiment that will prove it to
| > you. Take three bowls of water, the middle one tepid,
| > the right as hot as you can stand it and the one on the left
| > with ice cubes. Place your hands in the cold and hot
| > bowls for a couple of minutes, then place both in the tepid
| > water. The tepid water will feel warm to your left hand
| > and cool to your right hand, thus proving we detect
| > change rather than absolute temperature.
|
| I tried this, and confirm.
|
| It seems a strong argument in favor of heat flow;
| or temperature differential, anyway.
|
| --
| Rich
|
There is no proof better than experimenting for yourself,
and often the experiments are simple. Never believe all
you are told.
http://www.androcles01.pwp.blueyonder.co.uk/Algol/Algol.htm |
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