Who firstly draw diagrams of organ systems in human?

Answer 1

Credit for this is often given to the Greek Galen, living in de 2nd century. Galen however never studied human corpses, incorrectly assuming that his findings on dogs and pigs would fully apply to humans as well. Morover, studies on human anatomy had been made centuries earlier in ancient Egypt (authors unknown) and in Greece e.g. by Hippocrates and Herophilos.

The first European to systematically analyze and describe human anatomy based on actual dissections of humans was the Italian Mondino de Luzzi, also known by his latin name Mundinus, in the 13th century.