What does the respiratory system do? Which body system does it work most closely with? How do they work together to maintain homeostasis?

The respiratory system's main job is to move fresh air into your body while removing waste gases.

It works closely with the circulatory system.

The Respiratory system allows entry of oxygen into the body and releases carbon dioxide, the blood containing the oxygen is pumped across the lung tissue into blood vessels where the blood carries the oxygen around the body via the circulatory system, thus the respiratory and circulatory system work together in gas exchange which is vital in Homeostasis.