The importance of a four-chambered heart in human circulation; why does the heat need a double circuit?The importance of a four-chambered heart in human circulation; why does the heat need a double circuit?Form and function of arteries, veins, capillaries. How does each allow and control blood flow to and from the heart. Include information about gas exchange in capillaries.The form and function of the heart; how is the heart regulated (controlled)?The mechanics of negative pressure breathing and control of breathing based on body needs.The function of the structures of the respiratory system, including trachea and alveoli.