The thin-walled sac where oxygen and carbon dioxide are exchanged with the blood in the pulmonary circulatory system is a(n)
A) bronchiole
B) alveolus
C) tertiary bronchus
D) alveolar duct

Question

Quizplus · Accepted Answer

The vital gas exchange within the lung (called external respiration)takes place within the alveoli,extremely thin-walled sacs surrounded by blood capillaries,which represent the t parenchyma of the lung.Oxygen in the inhaled air diffuses from the alveoli into the blood capillaries.

The Thin-Walled Sac Where Oxygen and Carbon Dioxide Are Exchanged