My AP Bio class is way behind- we have 22 chapters left and 16 days until the exam, so my teacher paired us up and made each of the pairs "teach" a different chapter. My partner and I got Ch. 44, Controlling the Internal Environment.
I'm having trouble understanding the concept of the countercurrent heat exchanger, where arteries and veins run parallel from the body's core to an extremity, and the artereous blood warms the venous blood as the latter flows back to the heart. I understand how it works, but how does it minimize heat loss?
I think we're using different books. Mine explains it well in a diagram:
"This arrangement facilitates heat transfer from arteries to veins along the entire length of the blood vessel."
Let's say the "top" (artery) of the vessel is hot, and the "bottom" (vein) is cold. The blood flowing down it is then going to cool, and the blood flowing up warms.
Thus, instead of losing the heat when blood flows through the artery, it transfers it to the vein (which is trying to warm up), costing less energy to heat up and wasting less heat, minimizing heat loss.
In Cambells 6th Edition, this is figure 40.15.
Hope that helped =)
[URL=http://www.priceypixel.com]PriceyPixel.com - Free Signatures and Avatars by folks like you[/URL]
I can not agree with you more [url=http://www.gamelee.com]wow gold, and i think most people will approve [url=http://www.gamelee.com/age-of-conan-gold-1256.html]Age of Conan gold, too.