The primary function of the respiratory system is to provide oxygen to blood so that it can be transported to the various parts of the body. Respiration is the same as breathing. The parts of the respiratory system are:
The lungs – These major organs take the oxygen that we breathe in and make it available to the blood (that flows through the lungs). The waste product delivered back to the lungs by the blood is carbon dioxide. That is what we breathe out.
The nose (and the mouth) – This is where it all begins. Oxygen is brought in to the nose and down to the trachea. When carbon dioxide is expelled, it comes back through the trachea to the nose.