Internal Respiration Definition
Internal respiration is the process of diffusing oxygen from the blood, into the interstitial fluid and into the cells. Waste and carbon dioxide are also diffused in the other direction, from the cells to the blood. Oxygen is released from blood cells in response to the oxygen concentration in the capillaries of blood vessels, which is usually really low. This enables the exchange of gases and other solutes during internal respiration between the plasma and the interstitial fluid. Cellular respiration refers to the process of converting that oxygen along with glucose into ATP, a molecule that cells use to store usable energy, but creates carbon dioxide. External respiration refers to the process of exchanging oxygen and carbon dioxide in the lungs, gills, or other tissues exposed to the external environment. Breathing is the mechanical process of pulling the lungs into or out of the lungs or moving water over the gills.