Final answer:
The degree of stretch experienced by the sarcomeres in the ventricle cells before they contract is called preload. Preload is the amount of tension exerted on the ventricular muscle fibers when the ventricles are filled with blood. When the ventricles are filled with blood, the muscle fibers are stretched, and the sarcomeres lengthen.
Step-by-step explanation:
The degree of stretch experienced by the sarcomeres in the ventricle cells before they contract is called preload. Preload is the amount of tension exerted on the ventricular muscle fibers when the ventricles are filled with blood.
When the ventricles are filled with blood, the muscle fibers are stretched, and the sarcomeres lengthen. This increased stretch of the sarcomeres allows for a more forceful contraction when the muscles contract, increasing the stroke volume.
It is important to note that there is an optimal range of sarcomere length for maximum contraction force. If the sarcomeres are stretched beyond their optimal lengths, the force of contraction would decrease.