Respiratory surfaces in animals are the sites where gaseous exchange takes place. The respiratory surfaces in most animals show following features.
Large Surface
The surface area should be extremely large as it is seen in the lungs in the land vertebrates and in the gills in case of fishes.
Wet surface
The respiratory surface must be wet in order to carry out diffusion of gases.
Thin epithelium
The distance across which diffusion has to take place should be little. In most animals the epithelium which separate air and blood is only two celled thick. So the distance for diffusion is very short.
Ventilation
Ventilation maintains a steep diffusion gradient. There is a big difference in the concentration of the gases at two points which brings about diffusion.
Capillary Network
The respiratory site should possess extensive network of capillaries through which blood can pass at an adequate speed. In this way complete diffusion gradient is maintained which helps in rapid diffusion of oxygen.
Large Surface
The surface area should be extremely large as it is seen in the lungs in the land vertebrates and in the gills in case of fishes.
Wet surface
The respiratory surface must be wet in order to carry out diffusion of gases.
Thin epithelium
The distance across which diffusion has to take place should be little. In most animals the epithelium which separate air and blood is only two celled thick. So the distance for diffusion is very short.
Ventilation
Ventilation maintains a steep diffusion gradient. There is a big difference in the concentration of the gases at two points which brings about diffusion.
Capillary Network
The respiratory site should possess extensive network of capillaries through which blood can pass at an adequate speed. In this way complete diffusion gradient is maintained which helps in rapid diffusion of oxygen.
