Erasistratus (ĕrəsĭsˈtrətəs) [key], fl. 3d cent. B.C., Greek physician, b. Chios. He was the leader of a school of medicine in Alexandria, and his works were influential until the 4th cent. A.D. He considered plethora (hyperemia) to be the primary cause of disease. As opposed to the then current belief in the humors, he suggested that air carried from the lungs to the heart is converted into a vital spirit distributed by the arteries. He developed a reverse theory of circulation (veins to arteries). Studying from dissections, he observed the convolutions of the brain, named the trachea, and distinguished (as did his contemporary Herophilus) between motor and sensory nerves. He also devised a catheter and a calorimeter.
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