Which system is responsible for gas exchange in the body?

The respiratory system is the correct choice because it is specifically designed for the process of gas exchange, which involves taking in oxygen from the environment and expelling carbon dioxide produced as a waste product of metabolism. This system includes the airways, lungs, and the respiratory muscles, working in unison to facilitate breathing.

When air is inhaled, oxygen travels through the trachea, bronchi, and into the alveoli, where the actual exchange occurs. In the alveoli, oxygen diffuses across the alveolar membrane into the bloodstream, while carbon dioxide moves from the blood into the alveoli to be exhaled. This critical function allows the body to maintain the necessary levels of oxygen for cellular processes and remove carbon dioxide to maintain homeostasis.

Other systems mentioned do not perform gas exchange: the muscular system facilitates movement; the endocrine system regulates hormonal functions, and the cardiovascular system is responsible for transporting blood, nutrients, and gases throughout the body, but it does not directly handle the exchange of gases. Thus, the respiratory system is uniquely qualified for this vital physiological process.