explain the mechanism of gaseous exchange in humans.
Gaseous exchange in humans occurs through diffusion. In lungs, oxygen from alveolar air diffuses into blood vessels surrounding the capillaries and carbon dioxide from blood is given out into lungs. This oxygen is carried to the tissues and it diffuses from the blood vessels into the tissues. The carbon dioxide produced in the tissues diffuses into the blood vessels supplying the tissues, from where it is carried to the lungs.