Blood group antigens are carbohydrates that are attached to proteins or lipids. An antigen is a substance foreign to the body that causes an immune response. An immune response occurs when antibodies, which are proteins in your immune system, are summoned to attack an antigen.
Blood that reaches the lungs travels throughout a network of small blood vessels, where oxygen moves into the blood and carbon dioxide moves out of the blood, according to the National Heart, Lung and Blood Institute.
This helps them hold on to the oxygen too. These red cells pass through the tiny blood vessels in your lungs where the gas exchange takes place in the alveoli (like little bits of broccoli) over a large surface area. Carbon dioxide is expelled, and oxygen bonds to the iron in the red cells.The oxygenated blood then travels around the body to the cells, where it passes into individual cells using a process called osmosis.hese red cells pass through the tiny blood vessels in your lungs where the gas exchange takes place in the alveoli (like little bits of broccoli) over a large surface area. Carbon dioxide is expelled, and oxygen bonds to the iron in the red cells.