18.) When and by whom was the idea of a spherical Earth first developed?
O 1492 by Christopher Columbus
O 300 BC by philosophers in Ancient Greece
O hundreds of thousands of years ago by cavemen
O 1519 by Ferdinand Magellan

Define the apical impulse and describe its normal location, size, and duration. which abnormal conditions may affect the location of the apical impulse? explain the mechanism producing normal first and second heart sounds. describe the effect of respiration on the heart sounds. describe the characteristics of the first heart sound and its intensity at the apex of the heart and at the base. describe the characteristics of the second heart sound and its intensity at the apex of the heart and at the base.