Giovanni Borelli. Portrait of Giovanni Alfonso Borelli (1608-79), the Italian who applied mathematics to physiology and astronomy. Borelli studied the physiology of animal organs. He explained muscular action and the use of bones and joints as levers. He tried to explain the working of internal organs, such as the heart and lungs, but did not take account of the important chemical processes within them. In astronomy, Borelli postulated that Jupiter exerted a gravitational pull on its moons. He also drew attention to Kepler's and Horrocks' observations of elliptical orbits. Borelli was also the first to suggest that comets trace a parabolic path through the solar system.