Take the 2-minute tour ×
Biology Stack Exchange is a question and answer site for biology researchers, academics, and students. It's 100% free, no registration required.

It may be different for other people, but for me, anything above 32°C (90°F) is very uncomfortable, and my body is inclined to seek cooler temperatures. But I would think that at 32°C, the body would have less work to do to get itself to 37°C. So why is it not comfortable in those temperatures?

My theory is this, but I don't know if it's right:

The body's abilities for warming itself are much more sophisticated than its abilities for cooling itself (which are non-existent, possibly?). So it likes to be in an environment 20-30 degrees below optimal because it can easily handle that. But up in the 32's and we're dangerously close to going over the optimal, and the body doesn't know how to get it back down after that, so we are inclined to seek safer temperatures.

Is it something like that?

share|improve this question
    
not all animals require this body temperature - mammals have made some good business of assuming their bodies will all be at the same temperature and then warming themselves up to the right temperature. as the others note there are biological warmers, but no biological refrigerators, so choosing a temperature above most weather conditions was a useful part of the strategy of being warm blooded ... –  shigeta Jul 21 '12 at 15:37
    
I refer you to the quora answer: quora.com/Temperature/… –  bobthejoe Jul 24 '12 at 7:46
add comment

3 Answers

up vote 5 down vote accepted

The body can never stop working. If the body stops working, you die. And while the body is working it cannot avoid generating heat. Being in an environment somewhat colder than the body makes getting rid of this excess heat easier, and is thus more comfortable.

The body's abilities for warming itself are much more sophisticated than
its abilities for cooling itself (which are non-existent, possibly?).

The body can cool itself down by sweating.

share|improve this answer
    
Although in general this answer seems reasonable, I would like to see some references. What is the amount of heat generated by the body, say, when you're sleeping? Does it change during the day? Depending on the season? Is it actually that non-negligible (we are talking about a 16° difference here...) –  nico Jul 21 '12 at 7:05
    
It is quite a substantial amount of heat, and it is more when we are active so therefore more during the day. I don't have the resources available nor how to calculate those amounts. –  Hermann Ingjaldsson Jul 21 '12 at 8:44
    
Thermodynamically, your BMR goes nearly completely towards heat, as you do no work on the environment. I have a BMR of about 1800 kCal, so I need to lose all of that heat through my 2 square meters of skin every day. Some of that is insensible perspiration, and some of it is just conduction. –  Jeremy Kemball Aug 14 '13 at 20:17
add comment

Your body requires energy to function. Just like in a powerplant, the energy comes from oxidizing fuel (food, instead of coal or gas). The efficiency Of conversion is rather low, and results in excess heat, which must be rejected to the environment. When it's cool, the heat is easily convected to the surrounding air. When it's warmer, or you're producing more waste heat than can be rejected through simple convection, your body relies on evaporative cooling, i.e. sweating.

When it's very cold, the normal waste heat is not sufficient to keep you warm enough for normal bodily functions, so you shiver. This is physical activity which your body performs solely to create waste heat, which warms you up.

Here is a link to a Wikipedia article indicating that the human body is about 25% efficient. This means that about 75% of the energy consumed must be rejected as heat. http://en.wikipedia.org/wiki/Muscle#Efficiency

share|improve this answer
add comment

It may be different for other people, but for me, anything above 32°C (90°F) is very uncomfortable, and my body is inclined to seek cooler temperatures

I think you've rather nailed the key point here. I'm going to deduce from your question that you live in a temperate country? Every year, foreign students from India come over to my university in Leicester, UK. Even when the temperature is, to us, unpleasantly hot they will be shivering in their coats and complaining it's too cold. Similarly, were I to go over to India I'd be suffering in the heat while they're thinking it's a lovely comfortable temperature.

So, I believe, the answer is nothing to do with the ability of the body to maintain certain temperatures - you'd need to go considerably above 32°C or below 21°C to reach temperatures the body can't cope with - but rather a question of acclimatisation. You find 21°C comfortable and 32°C comfortable because that is the temperature that you've become used to. You can probably even recognise this from your own experience: I'm sure you've experienced days in spring feeling delightfully warm when days of the same actual temperature in autumn feel unpleasantly cold.

share|improve this answer
add comment

Your Answer

 
discard

By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.