Transcript Countercurrent in Fish

Circulation in Fish
Bulk flow and diffusion work together
to cause circulation. Bulk flow is
movement driven by pressure difference
in veins and arteries.
• Heart pumps blood in bulk to the gills ---O2 diffuses into the blood.
Countercurrent exchange - fluids or gases run
past each other in the opposite direction and
exchange heat or materials. (O2/CO2) Which
enables animals to establish steep gradients
of temperature or O2/CO2 concentration
Fish maximize absorption of O2 in gills
• Whales keep their fins from radiating heat
• Gazelles keep their heads from getting too hot
• Legs of wading birds don’t lose heat
• Testes in mammals