What does internal respiration refer to?

Internal respiration specifically refers to the process that occurs at the cellular level, where oxygen is utilized by the cells to produce energy through cellular respiration. In this biochemical process, cells consume oxygen to break down glucose, leading to the production of ATP (adenosine triphosphate), which is the energy currency of the cell. This process also generates carbon dioxide as a byproduct, which then needs to be transported back to the lungs for exhalation.

Understanding internal respiration is crucial because it highlights the role of oxygen in energy metabolism within tissues, distinguishing it from external respiration, which deals with the exchange of gases (oxygen and carbon dioxide) between the environment and the body's lungs.