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.
1 CAPILLARIES are blood vessels in the walls of the alveoli. 2  Blood passes through the capillaries, entering through your PULMONARY ARTERY and leaving via your PULMONARY VEIN. 3  While in the capillaries, blood gives off carbon dioxide through the capillary wall into the alveoli and takes up oxygen from air in the alveoli.ee what healthy lungs can do for you. Every cell in your body needs oxygen in order to live. The air we breathe contains oxygen and other gases. Once in the lungs, oxygen is moved into the bloodstream and carried through your body.