What is the primary function of external respiration?

The primary function of external respiration involves the exchange of gases between the atmosphere and the bloodstream. This process is essential for maintaining the body's oxygen supply and regulating carbon dioxide levels. During external respiration, oxygen from the air enters the alveoli in the lungs and diffuses into the blood, where it binds to hemoglobin in red blood cells. At the same time, carbon dioxide, which is a waste product produced by cellular metabolism, is transported from the blood into the alveoli to be exhaled.

This vital process not only supports cellular metabolism by ensuring that oxygen is available for energy production but also helps to maintain the acid-base balance in the body by regulating carbon dioxide levels. Without effective external respiration, the body would struggle to maintain proper respiratory and metabolic functions, highlighting why this answer accurately describes the primary function of external respiration.