How does gaseous exchange occur in the alveoli of the lungs?
1 Answer
Gaseous exchange at alveoli essentially occurs as a result of diffusion down a concentration gradient.
Explanation:
The main respiratory surface in humans is the alveoli. Alveoli are tiny balloon like structures with very thin walls. They have numerous tiny thin walled blood vessels in direct contact with them.
Inhaled oxygen is able to diffuse into the capillaries from the alveoli while carbon dioxide from the blood diffuses in the opposite direction into the alveoli. Differences in partial pressure of oxygen creates a gradient that causes oxygen to move from the alveoli to the capillaries and into the tissues .
Oxygen and carbon dioxide move independently of each other and diffuse down their own concentration gradients.
During physical exercise or increased respiration, the body responds by increasing the breathing rate, thus maximising the rate of possible gaseous exchange.
