You Have to Have Heart...

Krisidious · 13 Feb 2008, 17:37

so how is it that the heart of a mammal keeps us sooo warm? if you put water in a pump and flushed it back and forth, would it warm? and not only warm but all the way up to 98 degrees? no... so there are other tools at work, like lungs and arteries and tissue...

why are we so warm? homeostasis... so breathing and blood pressure help... but still no one explains the heat. is it a genetic heat blanket? if anyone knows I'd love to hear.

Jackson · 13 Feb 2008, 17:37

I think a lot of it has to do with friction in our muscles (including our heart). Every movement we make not only has to start, but has to stop- at any time there's an enormous amount of energy stored in our body as momentum- all those tiny little muscles twitching and moving even when we're asleep. Every time our brain tells our muscles to stop, or to move in the opposite direction (like our reciprocating lungs or heart) that "braking" action is exothermic so heat is produced.

Weirdly I was thinking about something similar a few weeks back (and this is an insight into how my overactive brain works ) - I got a new mountain bike which has disc brakes and noticed that even stopping from say just 10mph (16kph) the discs get extremely hot- any rain that lands on them fizzles and evaporates immediately. It occurred to me that the bike weighs only about 30lbs (14kg) compared to my 190lbs (85kg) so if I run at 10mph and then stop almost on the spot, somewhere in my body (or rather spread throughout) almost the same amount of heat must be generated. I love that thought- it makes you realise just how amazing natures "design" really is- Formula 1 cars are junk compared to us!
Sorry for my pub science, maybe someone who actually knows about physiology can chip in and prove me right or wrong.

Krisidious · 13 Feb 2008, 17:37

that's a great way to think of it... as I never have thought of it. a 190lb human breaking... that is a lot of energy. but sleeping we maintain this temp... I don't move much... at least I don't think I do.

Jackson · 13 Feb 2008, 18:48

@krisidious said:

but sleeping we maintain this temp... I don't move much... at least I don't think I do.

Yeah, but think of your heart, arteries and veins contracting and expanding more than once a second- every time every cell changes direction it produces a tiny amount of heat, but multiplied by millions I guess it adds up. Add to that the actual friction between our cells while they are moving and we are producing heat 24/7. Funnily enough I am ALWAYS too hot when I sleep- I often wake up sweating like crazy. My girlfriend needs the heating on and a thick duvet at night- I only sleep under a single sheet and even then only because it feels too weird to sleep without any cover at all.

While we're on the subject, I had a heating engineer tutor at Uni who actually ran the whole architecture building as a big energy experiment. He used to calculate the number of students who were in the building and at what times, multiplied by the heat they generated (I think it was 120kWh each) and had the heating/air conditioning programmed to take this into account! The result? Very low heating bills (I think combined with other unusual measures he got it down by over 30%)... and a cold building every Monday, getting gradually warmer as the week went on until it was just about right on Thursday. LOL

Rodentpete · 13 Feb 2008, 18:48

I'm pretty sure it's the mitochondria in all our cells that generate heat as they convert sugars into energy - heat is the byproduct, more energy is used by muscles so 30% of our heat is generated there. Friction in the body is bad - just ask my ankle joints

After a quick wiki-trip it seems that the idea of the heart heating the body is pretty old -http://en.wikipedia.org/wiki/Vital_heat

boofredlay · 13 Feb 2008, 18:49

I thought it was all the Midi-chlorians having sex then lighting cigarettes afterwards. They gotta reproduce as well right?

Daniel · 13 Feb 2008, 18:50

The body produces heat through the digestive system - food is broken down into fuel which the cells consume, and that consumption produces heat. The heart itself does not produce heat, but helps regulate the body's temperature by controlling the flow of blood.

Krisidious · 13 Feb 2008, 18:51

but you can starve yourself and not lose any heat... don't eat for days and you'll still be 98.6

Daniel · 13 Feb 2008, 18:51

One of the characteristics of starvation is lowered body temperature combined with extreme sensitivity to cold.

Skipping food for a few days is not starvation (for a healthy person). Our bodies have energy stored in fat.

Krisidious · 13 Feb 2008, 18:52

so the more fat you used the colder you'd get? and after all your stores were gone?

have you heard about those monks who bury themselves alive after fasting for like forever... crazy!

http://www.mymultiplesclerosis.co.uk/st ... mummy.html

Daniel · 13 Feb 2008, 18:52

You wouldn't feel any colder if your body has consumed fat reserves. It's only after those reserves are gone and the fuel is gone (starvation) would you feel the effects. That's not to say you wouldn't feel cold. Most people do. Just not the extreme sensitivity to cold.

There are other factors besides fat content and food consumption that affect body temperature - namely the body's ability to regulate temperature through circulatory system.