MICROANATOMY

Detailed explanation-1: -During gas exchange oxygen moves from the lungs to the bloodstream. At the same time carbon dioxide passes from the blood to the lungs. This happens in the lungs between the alveoli and a network of tiny blood vessels called capillaries, which are located in the walls of the alveoli.

Detailed explanation-2: -As the alveoli is rich in oxygen and tissues are rich in carbon dioxide(as oxygen is utilized there and carbon dioxide is released as a byproduct ), the gases get exchanged by diffusion along the concentration gradient. So, the gases get interchanged in between the lung and the tissues.

Detailed explanation-3: -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-4: -Diffusion is the spontaneous movement of gases, without the use of any energy or effort by the body, between the alveoli and the capillaries in the lungs.

Detailed explanation-5: -(ii) In humans, the exchange of gases takes place in the alveoli.