Vein
In the circulatory system, veins (from the Latin vena) are blood vessels that carry blood towards the heart. Most veins carry deoxygenated blood from the tissues back to the heart; exceptions are the pulmonary and umbilical veins, both of which carry oxygenated blood to the heart. Veins differ from arteries in structure and function; for example, arteries are more muscular than veins, veins are often closer to the skin and contain valves to help keep blood flowing toward the heart, while arteries carry blood away from the heart.
Read more about Vein: Anatomy, Function, Classification
Famous quotes containing the word vein:
“No man is quite sane; each has a vein of folly in his composition, a slight determination of blood to the head, to make sure of holding him hard to some one point which nature has taken to heart.”
—Ralph Waldo Emerson (1803–1882)
“As polishing expresses the vein in marble, and grain in wood, so music brings out what of heroic lurks anywhere. The hero is the sole patron of music.”
—Henry David Thoreau (1817–1862)