GENERAL HISTOLOGY

Detailed explanation-1: -The alveoli have a good air supply from the bronchioles and a rich blood supply. This is vital for successful gaseous exchange because it maintains a steep concentration gradient for oxygen from the air in the alveoli to the blood, and for carbon dioxide from the blood to the alveoli.

Detailed explanation-2: -The alveoli have a very large total surface area and a very good blood supply, provided by the dense network of capillaries that surround them. There is an exchange of gases between the alveoli and their surrounding capillary blood vessels. Oxygen diffuses from the alveoli into the blood.

Detailed explanation-3: -Breathing in and out (a ventilation mechanisms) maintains a steep concentration gradient between the oxygen (and carbon dioxide) in the alveoli and the blood so that the rate of diffusion is faster.

Detailed explanation-4: -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.

Detailed explanation-5: -Blood passes through the capillaries, entering through your PULMONARY ARTERY and leaving via your PULMONARY VEIN. While in the capillaries, blood gives off carbon dioxide through the capillary wall into the alveoli and takes up oxygen from air in the alveoli.