Erasistratus Biography (304 B.C.-250 B.C.)

physician, anatomist

Erasistratus, considered the father of physiology, was born on the island ofChios in ancient Greece. His father and brother were doctors, and his motherwas the sister of a doctor. He studied medicine in Athens and then, around 280 B.C., enrolled in the University of Cos, a center of the medical school of Praxagoras. Erasistratus then moved to Alexandria, where he taught and practiced medicine, continuing the work of Herophilus. In his lateryears, he retired from medical practice and joined the Alexandrian museum, where he devoted himself to research.

Although Erasistratus wrote extensively in a number of medical fields, none of his works survive. He is best known for his observations based on his numerous dissections of human cadavers (and, it was rumored, his vivisection of criminals, a practice allowed by the Ptolemy rulers). Erasistratus accurately described the structure of the brain, including the cavities andmembranes, and made a distinction between its cerebrum and cerebellum (larger and smaller parts). Contrary to popular belief at the time, he viewed the brain, not the heart, as the seat of intelligence. By comparingthe brains of humans and other animals, Erasistratus rightly concluded that agreater number of brain convolutions resulted in greater intelligence. He also accurately described the structure and function of the gastric (stomach) muscles and observed the difference between motor and sensory nerves. Erasistratus promoted hygiene, diet, and exercise in medical care.

In his understanding of the heart and blood vessels, Erasistratus came very close to working out the circulation of the blood (not actually discovered until William Harvey in the seventeenth century a.d.), but he made some crucial errors. Erasistratus understood that the heart served as a pump, thereby dilating the arteries, and he found and explained the functioningof the heart valves. He theorized that the arteries and veins both spread from the heart, dividing finally into extremely fine capillaries that were invisible to the eye. However, he believed that the liver formed blood and carriedit to the right side of the heart, which pumped it into the lungs and from there to the rest of the body's organs. He also believed that pneuma, avital spirit, was drawn in through the lungs to the left side of the heart,which then pumped the pneuma through the arteries to the rest of the body. The nerves, according to Erasistratus, carried another form of pneuma, animal spirit.

After Erasistratus, anatomical research through dissection ended, due to thepressure of public opinion. Egyptians believed in the need of an intact bodyfor the afterlife--hence mummification. Scientific anatomical studies were not resumed until the thirteenth century.

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