Answer:
The Respiratory system allows entry of oxygen into the body and release Carbon Dioxide. The Oxygen travels across lung tissue into blood vessels and the blood carries the oxygen around the body. Thus the Respiratory and Circulatory system work together in gas exchange which is vital in Homeostasis
The answer I think is the environment for this one. <span />
Nitrogen is released to the abiotic parts of the biosphere from the process death and by bacteria.