EVERYDAY SCIENCE

Detailed explanation-1: -Once the venous blood returns to the lungs, the carbon dioxide diffuses out of the bloodstream, through the capillaries, and into the alveoli from where it is expelled, during which time oxygen simultaneously binds with hemoglobin to be carried back to the tissues.

Detailed explanation-2: -Internal and external respiration At the same time, the carbon dioxide waste from the breakdown of sugars in the cells of the body diffuses into the blood and then diffuses from the blood into the lungs and is expelled as we breathe out. One gas (oxygen) is exchanged for another (carbon dioxide).

Detailed explanation-3: -In turn, exhaled air contains: nitrogen – 78% oxygen – 17% carbon dioxide – 4%

Detailed explanation-4: -Carbon dioxide (CO2) is a waste product of cellular metabolism. You get rid of it when you breathe out (exhale). This gas is transported in the opposite direction to oxygen: It passes from the bloodstream – across the lining of the air sacs – into the lungs and out into the open.

Detailed explanation-5: -CO2 is transported in the bloodstream to the lungs where it is ultimately removed from the body through exhalation. CO2 plays various roles in the human body including regulation of blood pH, respiratory drive, and affinity of hemoglobin for oxygen (O2).