Final answer:
Carbon dioxide leaves red blood cells in the pulmonary circulation, where it is eliminated from the body.
Step-by-step explanation:
The carbon dioxide leaves red blood cells in the pulmonary circulation. When deoxygenated blood returns to the heart, it enters the right atrium and then moves into the right ventricle. From there, it is pumped to the lungs through the pulmonary arteries for gas exchange. In the lungs, carbon dioxide diffuses out of the blood and is released into the alveoli, allowing for its elimination from the body.