I. Fick's Law & the Perfect Surface for Gas Exchange
II. Gas Exchange in Small Stuff
III. Gas Exchange in Fish
Play from 5 min 30 seconds for a nice explanation of countercurrent flow
In countercurrent flow - the blood flows in the opposite direction to the water.
It maintains the concentration gradient along the whole surface gas exchange surface (lamella)
This is an advantage because it allows for greater oxygen saturation of the blood (upwards of 80%)
Can you identify which of the image represent counter current and parallel flow?