where does gas exchange occur

Gas exchange in humans mainly occurs in the alveoli of the lungs, and also between blood capillaries and body tissues throughout the body.

Main locations

• In the lungs, gas exchange happens across the thin respiratory membrane between the air in the alveoli and the blood in pulmonary capillaries.

• In the tissues, oxygen leaves systemic capillaries and enters cells, while carbon dioxide moves from cells into the blood for transport back to the lungs.

Alveoli and respiratory membrane

• The respiratory zone includes respiratory bronchioles, alveolar ducts, alveolar sacs, and alveoli, where the actual gas diffusion takes place.

• The gas-exchange surface (alveolar–capillary membrane) is extremely thin and has a very large surface area, allowing efficient diffusion of oxygen and carbon dioxide.

External vs internal gas exchange

• External respiration is gas exchange between alveolar air and pulmonary capillary blood in the lungs (oxygen in, carbon dioxide out).

• Internal respiration is gas exchange between systemic capillary blood and tissue cells throughout the body, supporting cellular respiration.

Information gathered from public forums or data available on the internet and portrayed here.