How does countercurrent exchange work in fish?
Fish transfer oxygen from the sea water to their blood using a highly efficient mechanism called countercurrent exchange.
Countercurrent exchange means the flow of water over the gills is in the opposite direction to the flow of blood through the capillaries in the lamellae..
What animal uses cocurrent gas exchange?
Alternative arrangements are cross current systems found in birds. and dead-end air-filled sac systems found in the lungs of mammals. In a cocurrent flow system, the blood and gas (or the fluid containing the gas) move in the same direction through the gas exchanger.
Why is the countercurrent system of flow important for fishes?
Fish utilise a counter-current system in order to maximise the amount of oxygen that can extracted from water. Water has a much lower oxygen content than air and as such fish need a much more efficient system that can extract a much higher proportion of oxygen from the surrounding water.
What are the advantages of countercurrent flow?
In contrast, countercurrent oxygen exchange allows the blood to pick up 90 percent of the oxygen in the water. This impressive ability to acquire oxygen allows fish to thrive in water that has oxygen levels only a tenth of those at the top of Mount Everest, where most people cannot survive without supplemental oxygen.
What is the purpose of countercurrent flow in dialysis?
Principles of Hemodialysis Countercurrent flow maximizes the concentration gradient between blood and dialysate throughout the length of the dialyzer (see Box 22.1). When blood flow and dialysate flow are in the same direction (cocurrent), small solute clearance decreases by about 10%.
How does countercurrent flow work?
This is the way that a fish’s gills absorb the maximum amount of oxygen from the water. Water flows in the opposite direction to the blood flow in the gills to ensure that there is always a higher concentration of oxygen in the water than the concentration of oxygen in the blood.