AP BIOLOGY

Detailed explanation-1: -The alveoli are where the lungs and the blood exchange oxygen and carbon dioxide during the process of breathing in and breathing out. Oxygen breathed in from the air passes through the alveoli and into the blood and travels to the tissues throughout the body.

Detailed explanation-2: -In a process called diffusion, oxygen moves from the alveoli to the blood through the capillaries (tiny blood vessels) lining the alveolar walls. Once in the bloodstream, oxygen gets picked up by the hemoglobin in red blood cells.

Detailed explanation-3: -The smallest branches of the bronchial tubes are called BRONCHIOLES, at the end of which are the air sacs or alveoli. ALVEOLI are the very small air sacs where the exchange of oxygen and carbon dioxide takes place.

Detailed explanation-4: -By far, the most important site for absorption is the pulmonary region consisting of the very small airways called bronchioles and the alveolar sacs of the lung.

Detailed explanation-5: -The partial pressure of oxygen is high in the alveoli and low in the blood of the pulmonary capillaries. As a result, oxygen diffuses across the respiratory membrane from the alveoli into the blood. In contrast, the partial pressure of carbon dioxide is high in the pulmonary capillaries and low in the alveoli.