You probably learned your basic human anatomy sometime around grade school. Textbooks said your blood was red and a scraped knee on the playground confirmed it. We bleed red because of hemoglobin, an iron-containing protein that carries oxygen throughout the body. Hemoglobin is comprised of iron, which oxidizes as red like rust, causing our blood to be bright red when oxygen rich. So… Why Are My Blood Veins Blue? Join discussion...

A new machine that makes any blood type universal could lessen the risk of fatal transfusion mix-ups Join discussion...