Fish and Insect Gas Exchange

As their main gas exchange organ, fish use gills lungs spiracles capillaries( gills, lungs, spiracles, capillaries ). Their structure consists of an arch a loop a spiral filaments( an arch, a loop, a spiral, filaments ) from which filaments arches alveoli spiracles( filaments, arches, alveoli, spiracles ) project. Each filament contains many lamellae grana stomata( lamellae, grana, stomata ), through which capillaries run. This is the site at which gas exchange takes place. The blood flows through the capillaries in the opposite same( opposite, same ) direction as/to the water that flows through the gills, creating a countercurrent current anti-current monocurrent( countercurrent, current, anti-current, monocurrent ) exchange. This ensures there is a favourable gradient in water potential osmotic pressure oncotic pressure water flow( water potential, osmotic pressure, oncotic pressure, water flow ) between the water and the blood.