Book 10, Question 31
Why Do Veins Look Blueish Under Skin?
Veins look bluish under your skin, but the blood inside them is always red! Your skin filters light, so veins look blue or green. It is a trick of light, not blue blood.
More fun facts
- Octopus blood is blue because of a copper rich protein called hemocyanin that carries oxygen.
- Human blood uses hemoglobin, a protein with iron, which makes blood red.
- In icy Antarctic water, oxygen sticks so tightly to hemocyanin that one octopus makes extra hemocyanin to get enough oxygen.
- During exercise, swelling muscles push the veins under your skin toward the surface, so they look like they bulge.
- Both hemocyanin and hemoglobin let go of their oxygen when they reach body parts that need it.
Sources: National Geographic, Scientific American
Questions kids ask
What makes human blood red?
Hemoglobin, a protein with iron in it, which carries oxygen in our blood.