What function do the papillary muscles and chordae tendineae serve in the heart?

A. They are responsible for the contraction of the heart muscle:
Contraction is a function of the myocardium, not the arteries. Coronary arteries provide oxygen and nutrients, enabling contraction but do not generate force themselves.

B. They carry deoxygenated blood away from the heart muscle:
Coronary veins, not arteries, drain deoxygenated blood from the myocardium into the coronary sinus.

C. They supply oxygenated blood to the heart muscle:
Coronary arteries deliver oxygen-rich blood to the myocardium, ensuring the heart has the energy and oxygen needed for continuous contraction. Occlusion of these arteries can lead to myocardial infarction.

D. They regulate the heart's electrical impulses:
Electrical impulses are conducted via the SA node, AV node, bundle of His, and Purkinje fibers, not the coronary arteries.

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.