Which system is primarily responsible for gas exchange in the body?

The respiratory system is primarily responsible for gas exchange in the body. This system includes the lungs, airways, and associated structures that facilitate the intake of oxygen from the atmosphere and the expulsion of carbon dioxide, a waste product of metabolism. The process of gas exchange occurs in the alveoli, tiny air sacs in the lungs where oxygen diffuses into the bloodstream, and carbon dioxide is removed.

In contrast, while the circulatory system is important for transporting oxygen and carbon dioxide throughout the body, it is not the system responsible for the actual exchange of gases with the external environment. The digestive system focuses on the breakdown of food and nutrient absorption, and the urinary system deals with the excretion of waste products and regulation of water and electrolyte balance. Each system has its distinct functions, but the primary role of gas exchange is exclusively held by the respiratory system.