Michael LAVIN wrote: > > > We were talking today about thermoregulation in class and a > s student asked how young children ostensibly survive extreme > hypothermic trauma whreas adults fail to survive. I could > not answer why. Any help here? mlavin
On Fri, 15 Mar 2002, Tom Allaway replied > My understanding is that what's remarkable is their ability > to survive immersion in very cold water without suffering > brain damage from hypoxia, and that this is due to their > posession of a "dive reflex" which drastically reduces their > metabolic rate when so immersed, enabling them to go much > longer without oxygen before they start to suffer brain > damage. I was intrigued by this question so I did a bit of digging. PubMed was no help, but a Google search turned some stuff up. One of the first things I wanted to know was whether it was true. A number of sources do assert that children survive extreme hypothermic trauma better than adults, but without data. Assuming it's true, the next question is why. Harry Kallas, a professor of pediatric critical care medicine, UC-Davis, has an interesting discussion at: http://pedsccm.wustl.edu/All-Net/english/neurpage/protect/nr-dn.htm although he doesn't directly answer the question. He discounts the "dive reflex" hypothesis as "relatively quite weak in human adults and children". However, he points out that if hypothermia is to be protective, it must take place very rapidly. He also says that children are at particular risk for hypothermia given their high body surface area to mass ratio and lack of insulating fat. Putting these two together, I'd speculate that children may be more likely to survive extreme hypothermia (if in fact it's true) because their body temperature falls much faster than that of adults, so decreasing metabolic rate before hypoxemia can kill neurons. -Stephen ------------------------------------------------------------------------ Stephen Black, Ph.D. tel: (819) 822-9600 ext 2470 Department of Psychology fax: (819) 822-9661 Bishop's University e-mail: [EMAIL PROTECTED] Lennoxville, QC J1M 1Z7 Canada Department web page at http://www.ubishops.ca/ccc/div/soc/psy Check out TIPS listserv for teachers of psychology at: http://www.frostburg.edu/dept/psyc/southerly/tips/ ------------------------------------------------------------------------ --- You are currently subscribed to tips as: [EMAIL PROTECTED] To unsubscribe send a blank email to [EMAIL PROTECTED]
