Answer:
In the respiratory system, you inhale oxygen which is transferred to the blood in the alveoli and circulated throughout the body. The blood in the circulatory system has a protein called hemoglobin which binds to the oxygen and carries it throughout the body. This oxygen is then given to the different cells for cellular respiration. It then carries the waste products (CO2) of cellular respiration back to the lungs and it is exhaled out.