Final answer:
Respiration is the gas exchange process that includes inhaling oxygen and exhaling carbon dioxide, carried out by the respiratory system and is crucial for cellular metabolism.
Step-by-step explanation:
Respiration is the life-sustaining process in which gases are exchanged between the body and the outside atmosphere. This includes inhaling oxygen and exhaling carbon dioxide and other waste gases. It is accomplished mainly through the respiratory system and is essential for aerobic cellular respiration, which is a metabolic process where cells obtain energy by using oxygen to "burn" glucose, producing carbon dioxide as a waste product. Respiration involves two subsidiary processes: ventilation (breathing), the physical act of moving air to and from the lungs, and gas exchange, where oxygen and carbon dioxide are exchanged between the blood and the air in the lungs.