Friday, December 5, 2008

Brown fat

Last Thursday Dr. Ahmad mentioned brown fat during his discussion of various types of metabolism. He asked the class if we knew whether as adults, humans possess this type of fat. Someone responded by saying that, no as adults we do not, but in early childhood, we do. He said that was correct because this type of fat serves as a type of defense mechanism in the very young human being. He described how the brown fat is essential to polar bears of all ages because its properties allow an organism to preserve the energy of their body heat. So the polar bear core body temperature remains at a stable, warm and comfortable level because of this type of fat.
When we humans are very young (infant and toddler age) it can be difficult for us to gauge or sense when our environment is too extreme, (in terms of temperature), or even detrimental to our survival. He gave an example he had heard about some years ago: There was this little Canadian girl who somehow wandered out of the kitchen (where her mother was trying to simultaneously cook and look after her young daughter) and into the bitter winter environment of the wooded area directly outside her home. Once her mother became of aware of her absence, and searched with no avail, she notified the authorities and a search party was mobilized. They spent hours searching and after twelve hours they found her alive thankfully. It is in those extreme situations when the young human body is suddenly exposed to harsh environmental factors that may threaten their survival, that this brown fat is utilized. Dr. Ahmad said he believed that the temporary location of this fat is somewhere around the back of the head or the base of the skull. As we grow and mature we lose this fat so as adults we no longer possess it. Essentially its purpose is outgrown.

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