| Front | How do fish use a countercurrent system for gas exchange |
|---|---|
| Back | 1. water enters fish through the mouth 2.gills made of gill filaments creating a large surface area for diffusion of gases 3. Gill filaments covered in lamellae which increase the surface area 4. Lamellae covered in blood capillaries to decrease diffusion distance and maintain concentration gradient. 5. Blood flows in opposite direction to water flow. This allows the fish to maintain a concentration gradient between water and blood. The concentration of oxygen in water> concentration of oxygen in blood. |
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