Which anatomical regions of the heart are directly served by the right coronary artery?

A. Increase cardiac output by stretching the ventricles:
Stretching of the ventricles relates to preload, but papillary muscles and chordae tendineae do not directly stretch the ventricles to increase output.

B. Facilitate rapid conduction of electrical impulses:
Electrical conduction is carried by the SA node, AV node, bundle of His, and Purkinje fibers, not the papillary muscles or chordae tendineae.

C. Assist in opening the semilunar valves:
Semilunar valves (aortic and pulmonic) open due to ventricular pressure exceeding arterial pressure, not through papillary muscle function.

D. Prevent valve prolapse during ventricular contraction:
The papillary muscles contract during ventricular systole, pulling on the chordae tendineae, which anchor the mitral and tricuspid valves. This prevents backflow of blood into the atria (valve prolapse) and ensures efficient unidirectional flow.

A. Decreased preload increases cardiac output:
Decreased preload reduces ventricular filling, leading to lower stroke volume and reduced cardiac output.

B. Increased preload decreases cardiac output:
Increased preload generally increases stroke volume via the Frank-Starling mechanism, so it does not decrease cardiac output under normal physiological conditions.

C. Increased preload increases cardiac output:
According to the Frank-Starling law, greater ventricular filling (preload) stretches cardiac fibers, resulting in a stronger contraction and higher stroke volume, thus increasing cardiac output.

D. Preload has no effect on cardiac output:
Preload directly affects ventricular filling and stroke volume, which are critical determinants of cardiac output.