Respiratory: The human respiratory system is a series of organs responsible for taking in oxygen and expelling carbon dioxide. The cells of the human body require a constant stream of oxygen to stay alive. The respiratory system provides oxygen to the body’s cells while removing carbon dioxide, a waste product that can be lethal if allowed to accumulate. There are 3 major parts of the respiratory system: the airway, the lungs, and the muscles of respiration. The primary organs of the respiratory system are lungs, which carry out this exchange of gases as we breathe.