Wow, a Zulu-tanned horsehide.
Cool.

-Blast

Lasd02, I wasn't even poking fun at the authors of the information you offered, I was just wondering. The vet may be the most informed person on human heat loss on the face of the planet, which is fine with me. Everything that he says may well be true. It doesn't FEEL quite right, but that's just my opinion. He may have left out some important stuff that would have made me feel a bit better about it, and I think he could have explained it a bit differently/better. But that's also just my opinion.

Also my opinion: I know some vets that I would prefer to have do major surgery on me than many doctors. I worked for vets for thirteen years, so seeing the 'D.M.V.' threw me off, as I'm used to seeing DVM (Doctor of Veterinary Medicine) rather than 'Department of Motor Vehicles'. I went to my acronym finder site and typed in DMV, and there wasn't anything about a doctor's title (remember, this came from their own article). Anyway, I asked because in a human-related article, one might tend to think that they would list the human doctor first. It just seemed a bit strange to me, along with the typo on the DVM.

Now, keeping in mind that I just read ParamedicPete's last post and only understood part of it (small part, not large part), please recognize that I'm just tossing this out there, and don't even know if what I'm saying makes any sense to anyone else. Humor me on this, okay?

If a person's head is covered by 7-10% of their total skin surface, and the whole body is covered up except the head, and there's a cold wind blowing, does the 7-10% of the heat loss end when that 7-10% is gone, or is this one of those diminishing returns situations (I don't think that's the right phrase), where you lose the 7%, then you lose another 7%, and another and another, until your shivering can't compensate for the continued heat loss?

I'm sorry, but these are the kind of questions I ask EVERYONE. You're not my only victim... The vet I worked for in CA years ago got used to them, but he would warn relief vets before he left on vacation . One guy looked at me funny after assimilating one of my questions, and said, "Have you ever noticed that you have... odd thought processes?"

I just recently discovered that I have ADD, after all these years! Maybe that has something to do with it... or not.

Anyway, this has been a GREAT topic that you started. I wish you wouldn't take everything so personally, though. This is a DISCUSSION board. We discuss things. Sometimes we have a severe case of 'topic creep' (a term new to me). But just because we air our views doesn't mean we're attacking you, or even attacking the info you offer. Just imagine all of us in a large room chattering away and voicing our opinions --- the decibel level would be incredible! That's all it is. Don't take it personally, because it just isn't personal.

You've got 95 posts showing here. I've got... OMG! 1198! (Hey, Mods! Where is the rolly-eyed guy?) Do you think this means I'm opinionated? Think?

Sue

No apology necessary, my friend. It takes more than forum posting to offend me… I’d simply prefer to have my points debated on their merit if not simply for educational purposes.


Good point. I will admit that some of my notions are not supported by correlating research, however I do not believe that my points need correlating research. I’m not arguing against the results of your presented evidence. I’m arguing against the validity of the experiment as a whole in relevance to practical use of the myth.


You’re right. The environmental temperature may make a difference. However, I am not in a position to give this data, but we both agree that it might be an important factor to look at.


I do apologize for not explaining vasoconstriction correctly. As I understand, the body constricts the blood vessels on the surface of the skin and of the extremities simply to make the blood recirculate through them drastically slower than the blood in the core and head. The way I previously stated it was far too simplistic.

My point, however, still stands. Your evidence mentioned nothing about the rate at which different parts of the body lose heat in a vasodilated person versus a vasoconstricted one. Does it not make sense that a person who has symptoms of hypothermia such as vasoconstriction would lose a higher percentage of heat from their head and core than a person who’s in a normal physiological state? From your above comment, it appears that you do agree with this point.


Yes, I am asserting that your hair adds surface area to your head. Your analogies, on the other hand, kind of suck. (No offense.) Think of how a radiator’s fins add surface area when compared to just a stack of tubes. Even look at a heatsink in a computer for the effect… the fins or studs (large hairs, effectively) are simply there to add surface area.


I did say that it may act as a heatsink. After all, heat does conduct through different materials at different rates. When you touch an object and it feels cold, it is because that object is absorbing heat from your body through conduction. To put that in application to hair, ask yourself if your hair has ever felt cold when you touched it. If the answer is yes, then it proves that hair can conduct heat away from what it is touching. Put a convective air current through hair, and it may very well lose whatever heat it has absorbed to the air through convection.

Of course, the rates at which these occur are unknown to me, and your evidence only really eludes to the hair not doing a very good job of insulation. If it doesn’t do a good job of insulation, then maybe it does pretty well at facilitating the loss of heat. Maybe, as we are supposedly an evolutionary “tropical” animal, that’s what it was designed for. I don’t know. I’d love to see some research somewhere that answers these curiosities, though.


Actually, that is exactly what I am saying. Your research appears to simply say that people lose heat evenly through all exposed skin. And I quote:

So he took several test subjects, all volunteers, of course, (you have to wonder what problem they caused at the university), wired them to monitor their core temperatures, and discovered that we do indeed lose heat through any exposed part of the body and the amount of heat we lose depends on the amount of exposed surface area. The rate of heat loss is relatively the same for any exposed part of the body, not simply the head.

Therefore, it does appear to me that you are saying that the 10% heat loss from the head only applies to naked people, because that is exactly what your article (as quoted) is saying as well. So, I’m simply asking how on Earth this myth can only apply to exposed skin. As far as I know, none of us who read ETS, or have half a brain whatsoever, will be venturing into the cold naked. I sincerely doubt that many would be dumb enough to do so in just a T-shirt. So to me, this myth would apply to people who have at least made an effort to dress properly for their cold environment, except for a hat… especially for us here on ETS. Since in these circumstances, pretty much only our heads would be what might be exposed, then it seems logical that even your research states that most of our heat would be lost through the head.

So, I apologize if I misconstrued what your argument is. Your article says that people lose heat evenly through all exposed skin. I was simply saying that those results are irrelevant to a person in the cold who is reasonably dressed except for a lack of a hat. I invite you to clarify exactly what your argument is if I have misinterpreted it, as it appeared that you were trying to argue exactly what your article said.


True, that is what the myth specifically states, and if you think that somehow you only lose 7–10% of your body’s heat through your head even when properly winter dressed, except for a hat, I have a bad feeling you’re going to get a nasty surprise. So, when naked, the myth is not true. When properly dressed except for a hat, the myth may very well be true, hence “Don’t forget your hat.”


Don’t worry. I’m quite mature enough to not take words on a forum personally. The point that I’m trying to make is that the Wilderness Medicine research, while probably being scientifically correct, has absolutely no relevance to the myth since none of us will be going into the cold with completely exposed bodies thinking, “I have a hat. I’m saved!”

Besides, dead horses deserve to be punished for dying on us in the first place. Damn unreliable horse.

Partly, this discussion has strayed into hostile territory because we all have a tendency to confuse good advice with hard scientific evidence. Good advice may not always be "good" to the extent it claims - and science can inform us about its quantitative value. For instance, chicken soup may not cure the common cold, but science does confirm that it may be useful - for a number of somewhat complex and unrelated reasons. Those who used chicken soup as the sole treatment regimen for the cold were ill-informed - but anyone who might contend that it is of no value is almost equally wrong. And here's my point - the rate of mortality and morbidity from eating chicken soup is quite low, yet its salutary effect on the sick is well-documented in experience, thus, it is recommended! To the case in point I offer the following:

In support of keeping head and neck warm -- Three medical sources after a cursory review of the hypothermia treatment literature on the Internet:

?Individuals employing heated, humidified aerosols have been impressed with their benefits, which appear greater than can be explained by the small heat exchange. Most of the heat transfer takes place in the upper airway, not in the lungs where it would warm the heart. Investigators have speculated that warming the base of the brain and the brain stem may be responsible for the salutary effects.?

?The hypothalamus, a portion of the brain stem, is the body?s main thermometer
where most of the information from the temperature receptors in the core and skin are
integrated. The hypothalamus monitors these temperatures and when they start to vary, it
signals the body to bring the temperature back by voluntary and involuntary means.?

?Airway Warming
Airway warming accelerated rewarming to a statistically significant degree, compared with passive rewarming, whether it occurred before and/or after the period of airway warming. There is a thermal countercurrent heat exchanger in the cerebrovascular bed of humans known as the rete mirabile. This heat exchanger may preferentially rewarm the brainstem.?

So, until something better comes along, I will continue to insist on head and neck coverings (along with a whole host of recommended actions in cold weather) as beneficial to the person operating in cold conditions or suffering from early signs of hypothermia.

Cheers,