Is "Blood in your veins is blue" still taught in school?
Human blood is always red. Deoxygenated blood is dark red, not blue. Veins can look blue through skin because of how light scatters in tissue, not because the blood itself changes color.
What you were taught
Blood in your veins is blue
What we know now
Human blood is always red. Deoxygenated blood is dark red, not blue. Veins can look blue through skin because of how light scatters in tissue, not because the blood itself changes color.