What is the primary function of the respiratory system?

The primary function of the respiratory system is to facilitate gas exchange. This system is vital for delivering oxygen to the body and removing carbon dioxide, a waste product of metabolism. Oxygen enters the lungs when we inhale, and it then diffuses across the thin walls of the alveoli, small air sacs in the lungs, into the bloodstream. At the same time, carbon dioxide diffuses from the blood into the alveoli to be expelled during exhalation. This continuous exchange of gases is essential for maintaining the body's homeostasis and ensuring that cells receive the oxygen needed for cellular respiration and energy production.

In contrast, the digestive system is responsible for breaking down food, the circulatory system moves blood and nutrients throughout the body, and hormone production is mainly the function of the endocrine system. Each of these systems plays an important role in overall body function, but they do not directly handle the critical process of gas exchange like the respiratory system does.