oxygen
Gas exchange.
carbon dioxide
Oxygen
carbon dioxide
carbon dioxide
carbon dioxide
Methane Gas Oxygen Carbon Dixide Farts
red blood cells
The blood passes through tiny capillaries that lie in close proximity to the alveoli in the lungs. This is where the gas exchange takes place.
Carbon dioxide leaves the blood and goes into the alveoli where it can then be breathed out of the body. It is also at this point that oxygen passes into the blood to be carried to where it is required for respiration - carbon dioxide being a by-product of respiration.
oxygen
because of the presence of oxygen gas in the haemoglobin of the red blood cell.