Pulmonary vein three and five in the healthy population. The two left lobar veins may be united as a single pulmonary vein in about 25% of people; the two right veins may be united in about 3%. The pulmonary veins play an essential role in respiration, by receiving blood that has been oxygenated in the alveoli and returning it to the left atrium. As part of the pulmonary circulation they carry oxygenated blood back to the heart, as opposed to the veins of the systemic circulation which carry deoxygenated blood. A rare genetic defect of the pulmonary veins can cause them to
Blood red cyan, and consists only of magenta and yellow with a small amount of black. It is frequently darker than either maroon or dark red. Different sources have proposed different color schemes for the color blood red. Below are some of these. Blood red The color blood red is a dark shade of the color red meant to resemble the color of human blood (which is composed of oxygenated red erythrocytes, white leukocytes, and yellow blood plasma). It is the iron in hemoglobin specifically that gives blood its red color. The actual color ranges from crimson to a dark brown-blood depending