Answer 1:
Great observation!
Human blood is red due to the presence of iron
in hemoglobin, the protein in blood cells that
allows the transportation of oxygen throughout the
body. The color changes, however, depending on how
much oxygen is in the blood.
If there is a lot of oxygen in the blood, it
will appear bright red. This is common should
blood be taken from an artery, which takes blood
from the lungs to the rest of the body.
Deoxygenated blood is found in veins, which take
blood from the body back to the lungs. Blood drawn
from a vein will appear dark red or even black. So
your mom probably had a doctor take blood from a
vein. So the color is completely expected and
normal given how our body’s circulatory system
works.
While we are on the topic, there’s a persistent
myth you might have heard that blood is actually
blue until it encounters oxygen. People think this
is the case because veins, when viewed through
one’s skin, appear bluish. But this cannot make
sense as blood transports oxygen and the red
color comes from the iron. The bluish color of
veins actually has to do how light is absorbed by
skin. (Bonus fact: some organisms, like
squids and crabs, do have blue blood!)
Thanks for the great question.
Best,
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