What is the process our body uses to exchange gases with our environment?

The process the body uses to exchange gases with our environment is respiration, which encompasses both the mechanical and biochemical processes involved in taking in oxygen and expelling carbon dioxide. Respiration includes external respiration (the exchange of gases in the lungs) and internal respiration (the cellular use of oxygen and the production of carbon dioxide). During external respiration, oxygen from the air is absorbed into the bloodstream through the alveoli in the lungs, while carbon dioxide is released from the blood into the lungs to be exhaled. This continuous cycle is vital for maintaining the body's oxygen supply and eliminating waste gases.

While circulation refers to the movement of blood through the cardiovascular system, it is closely related but does not directly involve gas exchange. Diffusion describes the natural movement of gas molecules from an area of higher concentration to an area of lower concentration, which is indeed a mechanism that occurs during the gas exchange in the lungs but is not the overall term for the entire process. Ventilation involves the physical movement of air in and out of the lungs (i.e., breathing) and is a part of respiration but does not encompass the biochemical exchange of gases that occurs in the body.