What is the term for the process by which oxygen and carbon dioxide are exchanged in the lungs?

• A. Circulation
• B. Diffusion
• C. Ventilation
• D. Osmosis

Answer: (B)

The term that describes the exchange of oxygen and carbon dioxide in the lungs is diffusion. This process occurs primarily in the alveoli, which are the tiny air sacs in the lungs where gas exchange takes place. Diffusion is driven by the differences in concentration gradients: oxygen moves from an area of higher concentration in the alveoli to an area of lower concentration in the blood capillaries, while carbon dioxide moves in the opposite direction—from an area of higher concentration in the blood to an area of lower concentration in the alveoli. This simple but essential process is vital for respiration, as it ensures that oxygen is continually supplied to the bloodstream for transport to tissues and organs, while carbon dioxide, a waste product of metabolism, is removed from the body.

Understanding diffusion in this context helps to clarify how respiratory gases are exchanged efficiently and highlights its significance in overall respiratory function. The other options involve different biological processes: circulation refers to the movement of blood throughout the body, ventilation involves the mechanical process of breathing in and out, and osmosis is the movement of water across a semipermeable membrane, which is not directly related to gas exchange.