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.
Where does blood go after it picks up oxygen in the lungs? Topics | Heart and Circulatory System | Blood Basics | Where does blood go after it picks up oxygen in the lungs? Blood is pumped into the lungs by the right lower chamber of the heart, called the right ventricle.