A-level Biology Notes

Structure of gills in fish?

-many Gill filaments and Gill lamellae= large surface area.

-Gill lamellae have a thin wall (short diffusion distance) and are permeable.

-Ventilation brings in pure water (high oxygen, low carbon dioxide) and circulation brings in deoxygenated blood (low oxygen, high carbon dioxide), the water and blood pass over in opposite directions ( countercurrent flow), which maintains concentration gradient all the way along the Gill lamellae.