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Re: Necks and Brains



On Mon, 1 Apr 1996, Lloyd Gabel wrote:

> The diving reflex in aquatic mammals is a good example of selective 
> blood flow redistribution and shunting to the nervous system during hypoxic 
> periods by vasoconstriction and dilation.  We humans reflexly shunt blood 
> towards the brain when we suddenly stand up from a sitting or prone position 

We humans also reflexively shunt blood towards the brain when the face 
becomes covered with water, like diving mammals; but that is another story...

> James Norton's comments on tracheal dead space and airway resistance in long 
> necks are well taken, 

IMHO, it must be borne in mind in this sort of discussion that sauropod 
lungs were likely set up more like those of birds than of mammals or 
lizards, with the air entering a system of air sacs as it is inhaled and 
*exiting* through the lungs.  I'm not sure personally just what effects, 
if any, this might have on the air dynamics in a sauropod's windpipe, 
but it is something to consider.

Does air enter and exit a bird's respiratory tract through the same opening?

> Lloyd Gabel    LPGABEL@MSN.COM

Later!

Nick Pharris
Pacific Lutheran University
Tacoma, WA 98447
(206)535-8206
PharriNJ@PLU.edu