The lungs speed up to release carbon dioxide and increase the ph. The lungs attempt to increase the blood ph level by blowing off the carbon dioxide (carbonic acid). The excretion and retention of carbon dioxide (co2) are regulated by the lungs and therefore is a respiratory buffer system. Test-taking Hint: homeostasis is a delicate balance between acids and bases. The test taker can discard option a by realizing that production of urine does not affect the respirations.