MICROANATOMY

Detailed explanation-1: -Tiny air sacs at the end of the bronchioles (tiny branches of air tubes in the lungs). The alveoli are where the lungs and the blood exchange oxygen and carbon dioxide during the process of breathing in and breathing out.

Detailed explanation-2: -Gas exchange takes place in the millions of alveoli in the lungs and the capillaries that envelop them. As shown below, inhaled oxygen moves from the alveoli to the blood in the capillaries, and carbon dioxide moves from the blood in the capillaries to the air in the alveoli.

Detailed explanation-3: -During inspiration, air containing oxygen crosses the lung alveoli through diffusion. Then, it enters the blood and travels to various organs as well as tissues. Here oxygen is exchanged for carbon dioxide. The carbon dioxide exits the capillary of the blood, enters the blood and travels back to the lungs.

Detailed explanation-4: -Gas exchange in the alveoli occurs primarily by diffusion. Traveling from the alveoli to capillary blood, gases must pass through alveolar surfactant, alveolar epithelium, basement membrane, and capillary endothelium.

Detailed explanation-5: -Lung alveoli are found in the acini at the beginning of the respiratory zone. They are located sparsely in the respiratory bronchioles, lining the walls of the alveolar ducts. The alveoli are located in the alveolar sacs of the lungs in the pulmonary lobules of the respiratory zone.