>At 07:26 AM 4/1/98 +1000, you wrote:
>>>>Interesting! This suggests that this type of metabolic depression may also
>>>>combine with respiration in limiting the duration of a dive.
>
>I cannot agree with this conclusion. During exercise even mammalian
>athletes divert blood flow away from the skin and alimentary systems to
>supply the skeletal muscles, heart and brain. This is the reason why you
>should not eat much during or immediately after exercise. There is no need
>for a counter-current mechanism, the blood supply is just shut off to these
>non-vital organs - hence a drop in temperature. Of course catching a cold
>fish wouldn't help much either!
>
I agree with your comment about the temperature effects of the blood supply
being cut off to parts of the body. However, I suspect that the drop in
temperature in different parts of the body of penguins, as described in the
Nature (1997) article, is much greater in magnitude and rate than that
experienced by human athletes. In addition, we established in earlier
discussions that the penguin's heart rate slows down considerably during a
dive, whereas an athlete's would increase during exercise. Thus a penguins
metabolic rate would be decreasing, and an athlete's would be increasing.
Therefore, the physiological responses of a penguin during a dive appear to
be some of the early signs experienced by animals going into torpor.
Are you aware of any data which show temperatures in different regions of an
athlete's body during exercise, for comparison with penguins?
Cheers,
Stephen
**************************************************************
Dr Stephen Ambrose
Research Manager
Birds Australia (Royal Australasian Ornithologists Union)
Australian Bird Research Centre
415 Riversdale Road,
Hawthorn East,
VIC 3123.
Tel: +61 3 9882 2622
Fax: +61 3 9882 2677
Email: S.Ambrose <> (at work)
<> (at home)
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