This program examines how oxygen and carbon dioxide are transported throughout the body, guided by the brain as it reacts to internal and external stimuli. The process of breathing is modeled by a swimmer, the control of breathing by the brain is analyzed, and oxygen intake by the lungs and transport by red blood cells are discussed. The complementary actions of the circulatory and respiratory systems to meet the body’s energy needs are identified, and anaerobic respiration and oxygen debt are addressed. The internal structure of the heart is displayed. And the special properties of cardiac muscle tissue are outlined. The effects of smoke inhalation on the lungs from cigarettes and a house fire are also considered. (20 minutes)