According to Starling's Law, how does the cardiac muscle respond to stretching?

Starling's Law, also known as the Frank-Starling principle, describes how the heart's stroke volume and contractility are influenced by the degree of stretch on the ventricular walls, which occurs as the heart fills with blood during diastole. When the heart muscle fibers are stretched more due to an increase in blood volume returning to the heart, they generate a stronger contraction during systole, up to an optimal point. This relationship means that as the volume of blood in the ventricles increases, the heart responds by contracting with greater force.

This mechanism helps to match the output of the heart to the amount of blood returning to it, improving overall efficiency and maintaining hemodynamic stability. However, it's important to note that this increased force of contractility has a limit; excessive stretching beyond a certain point can lead to decreased contractility. Therefore, the correct response based on Starling's Law is that the force of contractility increases to a certain extent.