PATHOLOGY

Detailed explanation-1: -The walls of the alveoli share a membrane with the capillaries. That’s how close they are. This lets oxygen and carbon dioxide diffuse, or move freely, between the respiratory system and the bloodstream. Oxygen molecules attach to red blood cells, which travel back to the heart.

Detailed explanation-2: -Answer and Explanation: Alveoli of the lungs make close contact with blood capillaries. When a person inhales oxygen, alveoli are filled with more oxygen; thus, oxygen moves to from alveoli to blood capillaries with the help of diffusion (movement of particles from higher to lower concentration).

Detailed explanation-3: -While in the alveolar capillaries, the diffusion of gasses occurs: oxygen diffuses from the alveoli into the blood & carbon dioxide from the blood into the alveoli. Blood leaving the alveolar capillaries returns to the left atrium & is pumped by the left ventricle into the systemic circulation.