Preload is the same as EDV (end-diastolic volume).

Correct answer: True

Surface electrodes placed on the skin at specific anatomical locations detect the electrical impulses generated by the heart during depolarization and repolarization. These electrodes capture changes in voltage as the cardiac conduction system, including the SA node, AV node, bundle branches, and Purkinje fibers, propagates impulses through the atria and ventricles. The collected signals are transmitted to an electrocardiograph, which records the heart’s electrical activity as an electrocardiogram (ECG or EKG). This test provides critical information about heart rate, rhythm, conduction pathways, and possible ischemic or structural cardiac abnormalities.

Correct answer: False

Preload refers to the degree of stretch of the ventricular myocardial fibers at the end of diastole, just before ventricular contraction. It is influenced by the volume of blood returning to the heart (venous return) and the compliance of the ventricular walls. End-diastolic volume (EDV) is the actual volume of blood present in the ventricle at the end of diastole. While preload is closely related to EDV, it is a functional measure of myocardial fiber stretch rather than a direct measurement of blood volume. Thus, preload describes the mechanical tension on the myocardium, whereas EDV quantifies the volume of blood in the chamber.