Question

Each alveolus is surrounded by a web of blood capillaries supplied by the

Answer 1

pulmonary artery. The pulmonary artery carries deoxygenated blood from the heart to the lungs, where it branches off into smaller vessels until it reaches the capillaries surrounding the alveoli. Here, oxygen from the breathed air diffuses through the thin walls of the alveoli and into the blood, while carbon dioxide from the blood diffuses into the alveoli to be exhaled. The oxygen-rich blood then travels back to the heart through the pulmonary veins, where it is pumped to the rest of the body.