What is the primary function of the respiratory system?

The primary function of the respiratory system is to facilitate breathing and gas exchange. This system is essential for taking in oxygen from the atmosphere and expelling carbon dioxide, which is a waste product of metabolism. The process of breathing involves inhaling fresh air into the lungs, where oxygen is absorbed into the bloodstream, and then exhaling air that contains carbon dioxide.

Oxygen is vital for cellular respiration, which occurs in the body's cells to produce energy. Effective gas exchange is crucial for maintaining the body's pH balance and supporting overall cellular function.

In contrast, the other options refer to different bodily functions. Digestion pertains to the breakdown of food, production of hormones relates to the endocrine system, and blood circulation is managed by the cardiovascular system. Each of these systems plays a distinct role in the body, but the primary function of the respiratory system is centered on breathing and ensuring that oxygen is delivered to the tissues while removing carbon dioxide efficiently.