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 is where the exchange of oxygen and carbon dioxide takes place. After, oxygen passes into your blood and your blood carries the oxygen to every part of your body. Windpipe (Trachea)- The windpipe, also known as the trachea, takes the air from your mouth and nose into your lungs.