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?