This image shows the exchange of oxygen and carbon dioxide of a red blood cell. The first image is the carbon dioxide being picked up at the tissue. The second image is the pickup of oxygen in the lungs (alveoli).
autoimmune disorder and HLA. http://intranet.tdmu.edu.ua/data/kafedra/internal/meds/classes_stud/en/stomat/lik/ptn/clinical%20immunology/5/2.The%20immunological%20aspects%20of%20autoimmune%20diseases.files/image001.gif