Biology/Lungs and blood circulation
Considering evolutionary changes, how does have lungs change the basic blood circulation pattern of vertebrates. I know that lungs have large surface area over which oxygen can diffuse from he surrounding medium into the blood. I know that the movement of blood is from the heart, to the lungs, and back to the heart again. This means that blood goes back to the heart after the lungs, right? Or does it mean that having lungs allows the blood to move more quickly from the lungs to the body? Which statement is physiologically correct? Any explanation is appreciated.