Which two body systems must directly interact for vertebrate organisms to exchange gases?

Circulatory and Respiratory Systems

Answer: The circulatory system and the respiratory system.

Explanation:

During gaseous exchange between tissues, the blood is an essential function of the circulatory system. In humans, lower mammals, and birds, blood absorbs oxygen and it inturn releases carbon dioxide in the lungs. Hence, the circulatory and respiratory system, work hand in hand.