The changes in metabolic activity associated with endothermy and the change from gill to lung respiration has led to changes in vertebrate circulatory systems. Veins between two capillary networks are ...

The changes in metabolic activity associated with endothermy and the change from gill to lung respiration has led to changes in vertebrate circulatory systems. Veins between two capillary networks are ...

As blood stays within the blood vessels they have a closed system. Fish have gills instead of lungs. Oxygen in water moves into their blood via their gills. Their circulatory system has the same ...