What occurs during internal respiration?

During internal respiration, there is an exchange of gases between the blood and the body cells. This process occurs at the cellular level, where oxygen is transported from the blood into the cells, and carbon dioxide produced by cellular metabolism is transferred from the cells back into the blood for transport to the lungs. This is essential for maintaining cellular function, as oxygen is required for aerobic metabolism, and removing carbon dioxide helps maintain the acid-base balance in the body.

The other options describe different aspects of respiration. Inhalation of oxygen from the atmosphere pertains more to external respiration, which involves breathing in air into the lungs. Exhalation of carbon dioxide into the atmosphere also refers to external respiration, where gases are exchanged at the lung level rather than at the tissue level. Dissolution of gases in the lungs is related to how gases are absorbed by the blood but does not capture the essence of internal respiration, which is fundamentally about cell-level gas exchange.