ABSTRACT
Textbooks such as this necessarily focus on one aspect at a time (reductionism). But body systems function as parts of the whole body, not in isolation. Cardiovascular and respiratory functions are particularly closely interdependent: delivering oxygen and nutrients to tissues, while removing carbon dioxide and other waste. Respiration should achieve adequate tissue oxygenation, so gas movement across lung membranes forms external respiration, while gas movement between tissue cells and capillaries forms internal respiration.
