So this is our capillary, and inside the capillary, we have red blood cells. Our erythrocytes death carry our hemoglobin proteins. So within our red blood cell, we have many of these hemoglobin proteins as shown. And if we zoom in on a single hemoglobin, this is what we're going to see. So recall that our structure of hemoglobin contains four individual polypeptide subunits. So we have alpha one and alpha two.