Gas exchange occurs at the alveoli in the lungs and takes place by diffusion. The alveoli are surrounded by capillaries so oxygen and carbon dioxide diffuse between the air in the alveoli and the blood in the capillaries
We take in blood, which travels from our lungs to the alveoli. The alveoli "gives" the capillaries, containing air, oxygen. The capillaries 'owe' their carbon dioxide to the alveoli . When we exhale the carbon dioxide flows right out. However, the air we breathe out has a certain amount of oxygen.
Earth’s axis passes through the North and South Poles. It takes Earth 24 hours to rotate once around its axis. Earth revolves once around the Sun in 365 days during a non-leap year.
