Page 4 - Circulatory System in Finfish

Single vs. Double Circulation

Single Circulation Double Circulation

•Blood flows only once through •Blood flows twice through the

the heart during one cycle of heart during one cycle of passage

passage through the body. through the body.

•Fish have a single •The double circulatory

circulation system. system of blood flow refers to the

separate systems of pulmonary

•Only venous blood passes circulation and the systemic

through the heart circulation in amphibians, birds

and mammals.

•Mixed or oxygenated or venous

blood passes through the heart.