Final answer:
The primary function of the respiratory system is gas exchange, involving oxygen uptake and carbon dioxide removal. Air follows a path through the nasal cavity, pharynx, larynx, trachea, bronchi, bronchioles, to the alveoli. The pharynx serves both respiratory and digestive systems.
Step-by-step explanation:
The main function of the respiratory system is gas exchange. This vital process involves the transfer of oxygen into the body and the removal of carbon dioxide, which is a waste product of cellular respiration. The lungs, with their extensive network of alveoli, provide a large surface area for this purpose. It is in the alveoli that oxygen is taken up by the bloodstream and carbon dioxide is expelled from it. For this gas exchange to occur effectively, the respiratory system needs the cardiovascular system to transport the oxygen-rich blood to the body's tissues and return carbon dioxide-laden blood back to the lungs.
When air enters the body, it travels through the nasal cavity, pharynx, larynx, trachea, bronchi, bronchioles, and finally reaches the alveoli.
The organ that is part of both the digestive and respiratory systems is the pharynx.