What does 'respiration' encompass?

Respiration primarily refers to the process of inhalation and exhalation of air, which involves the exchange of gases—oxygen being absorbed and carbon dioxide being expelled. This biological function is critical for maintaining cellular respiration, which fuels energy production in the body.

While other processes, such as the absorption of nutrients and the elimination of waste products, are essential for overall bodily functions, they are distinctly separate from the respiratory process. Furthermore, the synthesis of hormones is related to endocrine functions rather than respiratory activities. Thus, the most accurate definition of respiration relates specifically to the movement of air in and out of the lungs.