Name the primary organ responsible for gas exchange in the respiratory system.

The primary organ responsible for gas exchange in the respiratory system is the lungs. Within the lungs, specifically in the alveoli—tiny air sacs surrounded by capillaries—oxygen from the inhaled air diffuses into the blood, while carbon dioxide, a waste product of metabolism, diffuses from the blood into the alveoli to be exhaled. This intricate process enables the body to obtain oxygen necessary for cellular functions and remove carbon dioxide, which is vital for maintaining the body’s acid-base balance.

The heart plays a critical role in circulation but is not involved in gas exchange. The trachea functions as a passageway for air between the throat and lungs and does not participate in gas exchange either. The diaphragm is a muscle that aids in the process of breathing by contracting and relaxing to change the volume of the thoracic cavity, thereby facilitating air movement in and out of the lungs. However, it does not partake directly in the exchange of gases.