Re: why do we produce heat and why do we give off heat?

Heat production, Heat release

I am going to assume you mean *how* are human beings producing heat in their 
own bodies, and why is is given off.  On that track, the first answer is 
mostly chemical, and the second one related to physics and the laws of 
thermodynamics.  (Don't hang up!  I promise to translate into english).

	First of all, in order for humans to "go," to move, to do things, to be 
alive, we need energy.  Since we can't get it from the sun, like plants do, 
or just from plain heat like some under sea organisms seem to, we have to 
get it from food.  When food is eated it is chemically processed, broken 
down from big bits like "cow" "banana" or "milk" into protiens, 
carbohydrates, fats, and minerals.  When chemical bonds are broken in this 
digesting process energy is released... some as energy our body then uses 
for other jobs, but quite a bit is released as heat, and that is what causes 
our bodies to heat up.  (Disclaimer.... that is a fairly simplified answer.  
There are many more steps than that, so as you learn more about this, the 
answer will no longer be just that simple, but it is a summary).  If you 
want to demonstrate this to your self, get a bit of wire and bend it back 
and forth many times to break it in half.  Feel the bendy spot.  It should 
feel warm. There are a few other things going on, but you are breaking it 
apart, and that will make the wire release heat.
	Second, why don't we keep that heat, why do we release it so we have to 
make more to keep our body temp at a comfy 98.6F?  This is physics.  The 
laws of thermodynamics say (among other things) that anytime you have a warm 
body (say your body) and a cool body (say the air in your room before the 
heater turns on in the morning), heat energy will transfer to the cool body 
to try to even things out (or create equilibrium).  Now you know that your 
body could never heat the room up to the temperature you want, and you 
certainly don't want your body to lose heat until it is the same temperature 
as your chilly room.  However, thermodynamics don't always follow what seems 
sensible to you, they follow the road to equilibrium.  Heat will always flow 
from a source of heat away to somewhere that is not so hot.  So put on your 
robe and slippers to keep all the heat from escaping, and have a good 
breakfast so you can keep making heat to keep warm.

Good Luck,
Greta Hardin