Tópico: Radiador Cerebral

[Feliperj]

Pessoal,

Com aproximadamente 2% da massa do corpo e 20% do consumo energético, o que faz com que nosso cérebro não "frite" ??

Abs
Felipe

[Luiz F.]

Como assim?

[Geotecton]

Como assim?

Como ele dissipa o calor produzido.

[Geotecton]

Pessoal,

Com aproximadamente 2% da massa do corpo e 20% do consumo energético, o que faz com que nosso cérebro não "frite" ??

Abs
Felipe

Possivelmente o calor seja dissipado pela intensa circulação sanguínea.

[_tiago]

Tem pouco gordura o cérebro e é onde mais perdemos calor. Tá com frio, põe uma touca que é bem eficiente.

[Feliperj]

Achei isso aqui :

http://saude.terra.com.br/bem-estar/bocejos-podem-ajudar-a-regular-temperatura-do-cerebro,93683f04c2f27310VgnCLD100000bbcceb0aRCRD.html

[Gigaview]

Why do we lose most of our heat through our heads when we exercise?
Barry S. Brown, University Professor of kinesiology in the College of Education and Health Professions, replies:


In general, heat loss is essential to provide thermoregulation and prevent excessive heat build-up in the body to avoid the consequences of heat stroke. However, heat loss in the head is the same as for any exposed body part. The exposed surface area of the body, along with relative humidity and temperature, determines heat loss primarily through evaporation and our head makes up only 10 percent of body surface area.  So, at rest, heat loss through the head accounts for only 7-10 percent of total heat dissipation.

The brain is supplied by blood flow through the cerebral and vertebral arteries, which also supply oxygen and heat to the brain. This flow does not change since the oxygen demand to the brain is constant.  However, as cardiac output is increased, the blood transported via the cerebral arteries to the brain also is increased. This increase in blood flow to the brain also results in an increase in the percentage of heat loss.  As you begin exercise, cerebral blood flow increases due to increased cardiac output and the percentage of heat lost through the head accounts for about 50 percent of total body heat loss.  As exercise continues, more oxygen is directed toward muscle and blood flow to this tissue increases. Core temperature has to be maintained and as body heat increases, the skin arterioles expand, or vasodilate, redirecting blood flow to the skin which cools the blood. Hence, total blood flow to the brain is decreased and the percentage of total body heat lost through the head is reduced to about 10 percent.  The percent lost through the scalp returns to 7 percent after sweating begins.

One important caveat occurs during hypothermia, or cold exposure.  If shivering occurs during hypothermia, 55 percent of the heat loss can occur in the scalp. Therefore, head covering during cold weather is strongly advised.

http://researchfrontiers.uark.edu/12401.php

[Buckaroo Banzai]

Será que a noção de cérebro como radiador do corpo teria tido isso como embasamento?

[Gigaview]

Não. Acho que o embasamento foi o motor a combustão mesmo.

[Buckaroo Banzai]

[...] During the 4th century BC Aristotle thought that, while the heart was the seat of intelligence, the brain was a cooling mechanism for the blood. He reasoned that humans are more rational than the beasts because, among other reasons, they have a larger brain to cool their hot-bloodedness.[3] [...]

http://en.wikipedia.org/wiki/History_of_neuroscience

[Gigaview]

ra·di·a·dor |ô|
adjectivo
1. Que radia ou irradia. = IRRADIADOR
substantivo masculino
2. Aparelho metálico ondeado que serve para aumentar a superfície irradiante do calor de gás, água ou vapor, para aquecimento de edifícios.
3. Pequeno aparelho usado para aquecer o ambiente. = AQUECEDOR
4. Aparelho destinado a arrefecer a água aquecida pelo motor de um automóvel.
Palavras relacionadas: irradiador, aquecedor, aquecimento, esquentador, escalfeta, calorífero, desaquecer.

"radiador", in Dicionário Priberam da Língua Portuguesa [em linha], 2008-2013, http://www.priberam.pt/dlpo/radiador [consultado em 27-12-2013].

Logo, "radiador" só pode ser utilizado em analogias de arrefecerimento após a invenção do motor de combustão interna, apesar de existirem outros "mecanismos de refrigeração" similares.

[Buckaroo Banzai]

Ou no mínimo da termodinâmica, uma vez que a radiação de calor por um corpo implica na perda de calor, não em seu aquecimento.