Which system is responsible for gas exchange in the body?

The respiratory system is responsible for gas exchange in the body. This system includes various organs such as the lungs, trachea, and bronchi, which work together to take in oxygen from the atmosphere and release carbon dioxide from the bloodstream. When air is inhaled, oxygen passes through the alveoli in the lungs and enters the blood, while carbon dioxide, a waste product produced by cellular metabolism, is expelled from the blood into the alveoli to be exhaled. This exchange of gases is crucial for maintaining the body's oxygen levels and removing carbon dioxide, which is essential for cellular respiration and overall metabolic function.

The other systems mentioned do not directly facilitate gas exchange. The circulatory system transports oxygen and carbon dioxide in the blood but relies on the respiratory system to perform the actual exchange. The digestive system is focused on breaking down food and absorbing nutrients, while the endocrine system regulates various hormones and body functions, neither of which involves gas exchange.