AP BIOLOGY

Detailed explanation-1: -Blood rich in carbon dioxide then returns to the heart via the veins. From the heart, this blood is pumped to the lungs, where carbon dioxide passes into the alveoli to be exhaled.

Detailed explanation-2: -Once the venous blood returns to the lungs, the carbon dioxide diffuses out of the bloodstream, through the capillaries, and into the alveoli from where it is expelled, during which time oxygen simultaneously binds with hemoglobin to be carried back to the tissues.

Detailed explanation-3: -The carbon dioxide moves out of the cells into the capillaries and bloodstream. Blood rich in carbon dioxide travels to the heart, which pumps it to the lungs. Carbon dioxide goes from the capillaries around the alveoli into the alveoli.

Detailed explanation-4: -Oxygen breathed in from the air passes through the alveoli and into the blood and travels to the tissues throughout the body. Carbon dioxide travels in the blood from the body’s tissues and passes through the alveoli to be breathed out.