Arteries carry blood from our heart to the rest of the body. They
allow for the delivery of oxygen and vital nutrients to our body's
organs and tissues.
Veins return the blood from the body's tissues and organs back to
the heart. The blood that flows back to the heart is fighting gravity.
Blood can flow against gravity in large part thanks to a series
of pockets located inside our veins. These pockets are called venous
These valves allow for blood flow in only one direction: upwards
toward the heart. When the valves become damaged, blood can run
backwards and pool in the vein. This results in increased pressure
inside the veins, which is the cause for veins we see through the
skin. These changes in the smallest veins are known as spider veins.
If the damaged veins are large and "ropy," they are known
as varicose veins.