# Are brains warm? **URL:** \ **Category:** Factual Questions\ **Created:** [April 5, 2012, 8:26am UTC](https://boards.straightdope.com/t/are-brains-warm/617898 "2012-04-05T08:26:38Z")\ **Posts on this page:** 15\ **Page:** 1
**Author:** ![Rigamarole](https://avatars.discourse-cdn.com/v4/letter/r/77aa72/32.png) [@Rigamarole](https://boards.straightdope.com/u/Rigamarole)\ **Post date:** [April 5, 2012, 8:26am UTC](https://boards.straightdope.com/t/are-brains-warm/617898/1 "2012-04-05T08:26:38Z")
How much of our natural internal body heat ends up in the brain? Do the fluids in the skull work to keep it cooler than the rest of the head? Basically, what I want to know is if you took a fresh brain out of the oven, what temperature would it be? ---
**Author:** ![Blake](https://avatars.discourse-cdn.com/v4/letter/b/a9a28c/32.png) [@Blake](https://boards.straightdope.com/u/Blake)\ **Post date:** [April 5, 2012, 9:32am UTC](https://boards.straightdope.com/t/are-brains-warm/617898/2 "2012-04-05T09:32:04Z")
> [@Rigamarole](#): > > How much of our natural internal body heat ends up in the brain? Except in cases of the most severe hypothermia, none at all. The brain is extremely well insulated and extremely energy intensive. IOW it generates a lot of heat and has no intrinsic way to lose it. Unless you are on the point of freezing to death the brain is a net \*exporter \*of heat. > [@](#): > > Do the fluids in the skull work to keep it cooler than the rest of the head? That depends entirely on the temperature of the rest of the head. Stand outside on a hot sunny day without a hat, and parts of the rest of the head can reach in excess of 55oC. The circulatory system sure works to keep the brain cooler than that. Conversely on a cold day parts of the head such as the ears and nose can drop down below 5oC even without invoking frostbite. The circulatory system certainly works to work to avoid those temperatures in the brain. The brain isn’t really special in this regard. You core temperature doesn’t fluctuate much, whereas your surface temperature can have a normal operational range in excess of 50oC. Your circulatory system works constantly to maintain core temperature by shunting heat around the body. The system used by the brain isn’t significantly different to that used by the liver or the heart or most other internal organs > [@](#): > > Basically, what I want to know is if you took a fresh brain out of the oven, what temperature would it be? ~37oC, same as your core temperature. ---
**Author:** ![CalMeacham](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/calmeacham/32/35_2.png) [@CalMeacham](https://boards.straightdope.com/u/CalMeacham)\ **Post date:** [April 5, 2012, 11:51am UTC](https://boards.straightdope.com/t/are-brains-warm/617898/3 "2012-04-05T11:51:27Z")
Aaaaahhhh! Dr. Jones – chilled Doper brains! ---
**Author:** ![willthekittensurvive](https://avatars.discourse-cdn.com/v4/letter/w/91b2a8/32.png) [@willthekittensurvive](https://boards.straightdope.com/u/willthekittensurvive)\ **Post date:** [April 5, 2012, 12:04pm UTC](https://boards.straightdope.com/t/are-brains-warm/617898/4 "2012-04-05T12:04:05Z")
Aristotle believed that the seat of human thought and emotion was the heart. Conversely, he believed that the main purpose of the brain was to cool the blood … ---
**Author:** ![Smeghead](https://avatars.discourse-cdn.com/v4/letter/s/f1d935/32.png) [@Smeghead](https://boards.straightdope.com/u/Smeghead)\ **Post date:** [April 5, 2012, 12:12pm UTC](https://boards.straightdope.com/t/are-brains-warm/617898/5 "2012-04-05T12:12:19Z")
Depends how hot the oven is, I’d think… ---
**Author:** ![md2000](https://avatars.discourse-cdn.com/v4/letter/m/73ab20/32.png) [@md2000](https://boards.straightdope.com/u/md2000)\ **Post date:** [April 5, 2012, 2:08pm UTC](https://boards.straightdope.com/t/are-brains-warm/617898/6 "2012-04-05T14:08:27Z")
The volume and speed of blood circulation is such that the whole body, except the surfaces, is at the same temperature. In fact, you are advised to wear a hat and scarf in the winter, because the amount of blood circulating through the head (and neck) is large enough that surface is a giant radiator in cool environments, especially if you have a large coat of blubber under your clothes elsewhere. A heavily clothed individual may lose over 1/3 of their heat through the head. One other datum I recall - is that the brain accounts for up to 1/3 of our calorie use. This is why few animals have relatively large brains; you need to get a benefit from that excessive use of energy. A cheetah for example, doesn’t need to be that smart - just faster than the prey. And… burning all those calories means, heat. Because humans evolved in part to chase down game by exhaustion (long distance running) on the plains of Africa, we have very well evolved circulation and sweat systems to handle shedding excess heat. Conversely, in cold our surface circulation reduces significantly, which explains why our skin goes “white”(whiter) when we are cold; less blood near the surface. ---
**Author:** ![Sailboat](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/sailboat/32/461_2.png) [@Sailboat](https://boards.straightdope.com/u/Sailboat)\ **Post date:** [April 5, 2012, 2:33pm UTC](https://boards.straightdope.com/t/are-brains-warm/617898/7 "2012-04-05T14:33:02Z")
[Secretly hoping this thread will get revived someday years from now, as it will make the BEST zombie thread ever!] ---
**Author:** ![aux203](https://avatars.discourse-cdn.com/v4/letter/a/77aa72/32.png) [@aux203](https://boards.straightdope.com/u/aux203)\ **Post date:** [April 5, 2012, 3:41pm UTC](https://boards.straightdope.com/t/are-brains-warm/617898/8 "2012-04-05T15:41:33Z")
> [@Blake](#): > > ~37oC, same as your core temperature. The temperature of the brain is considerably higher than your core temperature. About 1-2 degrees C depending on what probes you use and how you measure it. At rest the brain represents roughly 20% of total oxygen consumption. You don’t lose 1/3 or 1/2 of your body heat through your head unless you are wearing an Army issue arctic survival suit. Real world numbers are more like 10-20% depending on your clothing. The brain is not cooled significantly through the skull. The CSF around it and the massive blood flow it gets do most of the work of temperature regulation. 150-180 degree acrylic is allowed to cure in direct contact with the dura without ill effects (well, to the brain at least) on a semi-regular basis. ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [April 5, 2012, 7:54pm UTC](https://boards.straightdope.com/t/are-brains-warm/617898/9 "2012-04-05T19:54:55Z")
The OP appears to be under the misconception that fluids inherently tend to cool things. This is not true. The only relevance of fluids, in a contained environment, is that they can facilitate movement of heat from one place to another, via convective effects. A fluid will cool things off if it’s in contact with other cool things, but it’ll also heat things up if it’s in contact with other hot things: The spaghetti on the stove isn’t being kept cool by the water it’s in. Fluids can also be relevant on the outer surface of an object, since they can cool the object by evaporating (this is how sweat works). But the fluids in the brain are inside, not outside, so they can’t evaporate away. ---
**Author:** ![Rigamarole](https://avatars.discourse-cdn.com/v4/letter/r/77aa72/32.png) [@Rigamarole](https://boards.straightdope.com/u/Rigamarole)\ **Post date:** [April 5, 2012, 8:12pm UTC](https://boards.straightdope.com/t/are-brains-warm/617898/10 "2012-04-05T20:12:14Z")
> [@Chronos](#): > > The OP appears to be under the misconception that fluids inherently tend to cool things. Well, I was more under the impression that they were for insulation. I just didn’t know if the brain produced its own heat or what (and apparently this is indeed the case). ---
**Author:** ![Jackmannii](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/jackmannii/32/311_2.png) [@Jackmannii](https://boards.straightdope.com/u/Jackmannii)\ **Post date:** [April 5, 2012, 8:37pm UTC](https://boards.straightdope.com/t/are-brains-warm/617898/11 "2012-04-05T20:37:15Z")
What does the OP want with oven-roasted brainsss? ---
**Author:** ![Napier](https://avatars.discourse-cdn.com/v4/letter/n/ce73a5/32.png) [@Napier](https://boards.straightdope.com/u/Napier)\ **Post date:** [April 5, 2012, 8:54pm UTC](https://boards.straightdope.com/t/are-brains-warm/617898/12 "2012-04-05T20:54:46Z")
The brain produces its own heat and the blood cools it, by moving its heat to other locations as cooler blood enters the brain and displaces warmer blood that was in it. It’s an interesting heat transfer phenomenon. If the volumetric specific heat of water was somehow magically reduced from its present value somewhere around 4 million joules per cubic meter kelvin to half that (where most substances are), we’d all die from overheated brains. ---
**Author:** ![Rigamarole](https://avatars.discourse-cdn.com/v4/letter/r/77aa72/32.png) [@Rigamarole](https://boards.straightdope.com/u/Rigamarole)\ **Post date:** [April 6, 2012, 12:51am UTC](https://boards.straightdope.com/t/are-brains-warm/617898/13 "2012-04-06T00:51:19Z")
> [@Jackmannii](#): > > What does the OP want with oven-roasted brainsss? The oven was metaphoric, however I’m not one to turn down piping hot brains. ---
**Author:** ![Covered\_In\_Bees](https://avatars.discourse-cdn.com/v4/letter/c/7ab992/32.png) [@Covered\_In\_Bees](https://boards.straightdope.com/u/Covered_In_Bees)\ **Post date:** [April 6, 2012, 2:14am UTC](https://boards.straightdope.com/t/are-brains-warm/617898/14 "2012-04-06T02:14:06Z")
Then it’s settled, piping hot brains at the next Dope Fest! Surely one of these damn Spring Break kids won’t be missed, amiright? On a related note, does intelligence or high amounts of brain activity affect the taste, texture or chewiness of a brain? ---
**Author:** ![Derleth](https://avatars.discourse-cdn.com/v4/letter/d/b9e5f3/32.png) [@Derleth](https://boards.straightdope.com/u/Derleth)\ **Post date:** [April 6, 2012, 2:52am UTC](https://boards.straightdope.com/t/are-brains-warm/617898/15 "2012-04-06T02:52:36Z")
> [@Rigamarole](#): > > Well, I was more under the impression that they were for insulation. I just didn’t know if the brain produced its own heat or what (and apparently this is indeed the case). Well, yes: It consumes a lot of glucose and turns it into you. This is an exothermic process, and your brain does a lot of it: [“[t]he human brain, at 2% of body mass, consumes about 20% of the whole body energy budget”.](http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3046985/?tool=pubmed) Compare that to other vertebrates, which spend between 2-10% of their energy budget on their brains on average. (Citation for paragraph: Herculano-Houzel S (2011) Scaling of Brain Metabolism with a Fixed Energy Budget per Neuron: Implications for Neuronal Activity, Plasticity and Evolution. PLoS ONE 6(3): e17514. doi:10.1371/journal.pone.0017514) Also, yes, [thinking harder may mean you burn more energy doing it](http://www.physicsforums.com/showpost.php?p=306423&postcount=5): > [@](#): > > Average- [mean IQ 104] and high-IQ [mean IQ 123] subjects hardly differed in GMR [glucose metabolic rate] on the “easy” items but differed markedly on the “difficult” items. The high-IQ subjects brought more “fuel” to bear on the more difficult task. The citation for this goes to: Larson G. E., Haier R. J., LaCasse L. & Hazen K. (1995). Evaluation of a “mental effort” hypothesis for correlations between cortical metabolism and intelligence. Intelligence, 21, 267-278.