Where does gas exchange of carbon dioxide and oxygen occur?

The process of gas exchange of carbon dioxide and oxygen primarily occurs in the lungs. Within the lungs, specifically in the alveoli – tiny air sacs – oxygen from the inhaled air enters the bloodstream while carbon dioxide, a waste product of metabolism, is expelled from the blood into the alveoli to be exhaled. This exchange is crucial for maintaining respiratory and metabolic balance in the body.

The heart plays a vital role in circulating blood but does not participate in the actual gas exchange process. The liver is primarily involved in metabolic processes, detoxification, and the production of important substances like bile. The kidneys are responsible for filtering blood, regulating electrolytes, and producing urine, but they do not participate in gas exchange. Thus, the lungs are the correct answer for where gas exchange occurs.