Final answer:
Internal respiration is the exchange of gases that occurs at the tissue level, involving the movement of oxygen from the blood to the tissues and carbon dioxide from the tissues to the blood. This occurs through simple diffusion driven by a partial pressure gradient.
Step-by-step explanation:
Internal respiration is the exchange of gases that occurs at the tissue level. It involves the movement of oxygen from the blood to the body tissues, and the movement of carbon dioxide from the body tissues to the blood. This exchange happens through simple diffusion, driven by a partial pressure gradient. For example, oxygen dissociates from hemoglobin in the blood and diffuses into the tissues where it is needed for cellular respiration.
Internal respiration is different from external respiration, which is the exchange of gases between the atmosphere and lungs during breathing. It is also different from cellular respiration, which is the process by which cells produce energy using oxygen. Internal respiration specifically refers to the gas exchange that occurs at the tissue level.