My teacher said our veins carry blue blood. My mom says we have dark red blood in our veins and bright red blood in our arteries. Who is right?

Kendall,

The body does not have blue blood.  The terms “red” and “blue” are used in diagrams in order to show the difference in oxygentated and deoxygenated blood. 

All blood is red. 

However, arterial blood, blood traveling in your arteries, is rich is oxygen while venous blood, blood traveling in your veins, is a darker red.  It is poor in oxygen.  It only appears “blue” in your veins because the skin actually diffuses light.  Blood does not reflect light well, so as light travels through your skin, the reflected color is a dark, deep bluish red color.   

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