The endocardium lines the internal chambers of the heart.

A. Left and right atria: The left and right atria receive blood from the pulmonary veins and the venae cavae, respectively. Electrical conduction to the atria originates from the sinoatrial node and spreads through atrial myocardium via internodal pathways. The Bundle of His does not divide into atrial structures, as it functions within the ventricular conduction system.

B. Left and right ventricles: Although the Bundle of His ultimately conducts impulses that stimulate ventricular contraction, it does not anatomically split into the ventricles themselves. Instead, it divides into specialized conduction pathways that distribute impulses within ventricular myocardium.

C. Purkinje fibers: Purkinje fibers are specialized subendocardial conducting fibers located along the inner walls of the ventricles. They arise distally from the bundle branches and rapidly transmit electrical impulses to ventricular myocardial cells to coordinate contraction. The Bundle of His does not split directly into Purkinje fibers but first divides into bundle branches.

D. Left and right bundle branches: The Bundle of His, located in the interventricular septum, divides into the left and right bundle branches. These branches descend along either side of the septum toward the apex of the heart. They conduct electrical impulses from the atrioventricular node to both ventricles, ensuring synchronized ventricular depolarization before distribution to Purkinje fibers.

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.