Because there is often no way to measure every instance of a phenomenon around the entire world, scientists . can do little more than guess at what’s happening

do not even attempt to do so

use statistical sampling and mathematical models to make estimates

use computer simulations instead

pick one instance and assume it’s representative

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.