Answer:
Alveoli
Step-by-step explanation:
Gas exchange refer to the transmission of oxygen from the lungs to the bloodstream and removal of carbondioxide from the bloodstream to the lungs.
Gas exchange occur in the alveoli of the lungs and the capillaries envelope in them. Alveoli is responsible for diffusion of gases to the blood stream through the lungs and removal of gases.
Inhaled oxygen is moved from the alveoli to the blood capillaries and carbondioxide is eliminated from the blood capillaries into the alveoli.