EVERYDAY SCIENCE

Detailed explanation-1: -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-2: -Why oxygen does diffuses into the blood capillaries in the lungs, but out of the blood capillaries in the tissues. In lungs, partial pressure of oxygen is higher in the alveoli of lungs than in capillaries. So, oxygen diffuses down the pressure gradient (oxygen moves out of the alveoli into the capillaries).

Detailed explanation-3: -How does oxygen get into the bloodstream? Inside the air sacs, oxygen moves across paper-thin walls to tiny blood vessels called capillaries and into your blood. A protein called haemoglobin in the red blood cells then carries the oxygen around your body.

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: -Summary. Oxygen enters the lungs, then passes through the alveoli and into the blood. The oxygen is carried around the body in blood vessels. Carbon dioxide moves into the blood capillaries and is brought to the lungs to be released into the air during exhalation.