Gas Exchange

Gas exchange is the process by which oxygen enters an organism and Carbon dioxide is removed from an organism.  Not all organisms use gas exchange.  During the process of gas exchange, newly inhaled air is drawn into the alveoli of the lungs alveoli.  Alveoli are small sacs of tissue lined with many capillaries (small blood vessels). As the air enters them, the process of diffusion occurs. Because there is a high concentration of oxygen in the air and a lower concentration in the blood, some of the oxygen in the air transfers through a membrane to the blood.  Carbon dioxide diffuses also through the membrane form the blood into the air.