Final answer:
Starling's Law of the Heart states that increasing the stretch of the ventricular muscle increases the strength of contraction and stroke volume.
Step-by-step explanation:
The relationship between ventricular stretch and contraction is known as Starling's Law of the Heart. This principle states that the force of heart contraction is directly proportional to the initial length of the muscle fiber. When the ventricular muscle is stretched, there is increased overlap between actin and myosin, allowing more myosin heads to bind to actin and form cross bridges, resulting in a more powerful contraction and increased stroke volume (SV).
In summary, myocardial stretch influences contractility and SV through the adjustment of actin and myosin filament overlap in the sarcomeres, according to the length-tension relationship. This relationship is an essential aspect of the heart's ability to adjust its pumping force in response to varying levels of blood volume returning to the heart.