AEMCA Practice Exam

What does Starling's law state?

1. The heart rate is consistent regardless of activity

2. The strength of each contraction increases with the stretch of the ventricles

3. The heart can operate effectively under low oxygen conditions

4. The heart's electrical activity is synchronized with breathing

The correct answer is: The strength of each contraction increases with the stretch of the ventricles

Starling's law, often referred to as the Frank-Starling law of the heart, states that the strength of each contraction of the heart's ventricles increases with the degree of stretch of the heart muscle fibers. This means that the more the cardiac muscle fibers are stretched during filling (due to increased blood volume), the stronger the subsequent contraction will be. This physiological principle is crucial for maintaining cardiac output and ensuring that the heart can efficiently pump blood in response to varying levels of venous return. Understanding this law is important because it highlights how the heart automatically adjusts its pumping capacity based on the volume of blood it receives, ensuring that it can meet the body's demands during different activities. The other options do not accurately describe the specific physiological principle laid out by Starling's law. For instance, while the heart does respond to different oxygen levels and maintains a certain rhythm with breathing, these factors are not encapsulated by Starling's law.