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 The primary function is to pump blood into the high‐pressure systemic (left ventricle) and low‐pressure pulmonary (right ventricle) circulations.

 As described by the Law of LaPlace (see Table 3.1), the thick‐walled, conical left ventricle is better suited for high‐pressure pumping than the thin‐walled, flattened right ventricle.

Table 3.1 Summary of physiologic laws pertaining to the cardiovascular system.

Name of Law	Formula	Formula components	Application
LaPlace	T = P x R	T = TensionP = pressureR = radius	For any given pressure, the tension developed by the wall of the ventricle increases as the radius of the cylinder increases.
	The left ventricle has a much greater radius than the right ventricle and thus is able to develop greater tension (or force).(LV = left ventricle; RV = right ventricle)
Ohm's	Q=∆P/R	Q = blood flow∆P = the pressure difference (P1‐P2) between the two ends of the vessel.R = resistance	Blood flow is directly proportional to pressure difference and inversely proportional to resistance.
	Thus, the difference in pressure between the two ends of the vessel determines the rate of flow and not the absolute pressure in the vessel.
Poiseuille’s	Q=π∆Pr4 / 8ηl	Q = blood flow∆P = the pressure gradientr = the radius of the vesselη = the viscosity of the bloodl = the length of the vesselπ relates to the vessel radius	Blood flow is directly proportional to the 4th power of the radius of the vessel as long as the flow is laminar.Slight changes in the diameter of a vessel cause tremendous changes in flow because blood flowing in the middle of the vessel flows freely, whereas blood at the periphery flows slowly because of friction caused by the endothelium of the vessel wall. In a small vessel, a large percentage of the blood is in contact with the vessel wall so the rapidly flowing central stream of blood is absent.
	Changes in vessel diameter greatly influence blood flow (Q).
Starling's	None	None	Within physiological limits, stretched cardiac muscle (and other forms of striated muscle like skeletal muscle) will contract with greater force.
	The force of contraction of the cardiac muscle is proportional to its initial length.When the diastolic filling of the heart is increased or decreased with a given volume, the displacement of the heart increases or decreases with this volume.Excessive stretch can result in decreased contractility.