What is internal respiration?

Internal respiration refers specifically to the process of gas exchange between the blood and the tissues of the body. During internal respiration, oxygen is delivered from the bloodstream into the cells, where it is utilized for metabolic processes. Simultaneously, carbon dioxide, which is a byproduct of cellular metabolism, moves from the tissues into the bloodstream to be transported back to the lungs for exhalation. This exchange is crucial for maintaining cellular respiration and overall physiological balance within the body.

In contrast, other options describe different respiration processes. Breathing air from the environment describes external respiration, the mechanism by which air is brought into the lungs. Gas exchange at the alveoli involves the transfer of gases between the air in the lungs and the blood, which is another aspect of external respiration. Movement of air into the lungs solely pertains to the action of ventilation rather than the exchange processes that occur in the tissues. Thus, understanding that internal respiration specifically highlights the exchange of gases at the cellular level is essential for grasping how our bodies utilize oxygen and eliminate carbon dioxide.