How does the Respiratory System maintain homeostasis?

The respiratory system maintains homeostasis by gathering oxygen from the air and by getting rid of metabolic wastes which are substances that are left over from the excretory processes. Blood that is within the artery is oxygen-poor and contains a large concentration of CO2 also known as Carbon Dioxide. Blood would pass through the capillaries which surrounds the alveoli, and oxygen diffuses into blood and CO2 diffuses out of blood leading to the alveoli. Therefore, Carbon Dioxide exhales out of the living organism from moving the alveoli to the nose. Since there is a result of oxygen being rich and a small concentration of carbon dioxide in the pulmonary vein it shows that CO2 has been replaced with oxygen as blood passes through the lungs.