A change in preload causes a change in myocardial contractile force.This response is known as (a)
A)(+) inotropic effect.
B)(+) dromotropic effect.
C)Starling's law of the heart.
D)(-) chronotropic effect.

Question

Quizplus · Accepted Answer

Starling's law of the heart states that an increase in preload (the stretch of the ventricles prior to contraction) results in an increase in the force of contraction of the myocardium. This is due to an increased sensitivity of the cardiac myofilaments to calcium ions, resulting in stronger actin-myosin cross-bridges and greater force of contraction. Therefore, option C is the correct choice. A) refers to an increase in contractile force due to an independent effect on calcium handling in the myocardium, B) refers to the electrical conduction of the heart, and D) refers to heart rate.

A Change in Preload Causes a Change in Myocardial Contractile