Vasoconstriction of blood vessels lowers afterload by making it easier for the heart to pump blood.

Correct answer: F.

A. Trabeculae carneae: These are irregular, muscular ridges lining the inner walls of the ventricles. They prevent suction during contraction, aid in ventricular contraction efficiency, and contribute to overall cardiac structural integrity.

B. Pulmonary semilunar valve: This valve is located between the right ventricle and pulmonary artery. It prevents backflow of blood into the ventricle during diastole and ensures unidirectional pulmonary circulation toward the lungs.

C. Papillary muscles: Papillary muscles are conical projections of ventricular myocardium that anchor chordae tendineae. During ventricular contraction, they contract to prevent inversion or prolapse of atrioventricular valves, ensuring proper unidirectional blood flow.

D. Pectinate muscles: Pectinate muscles are comb-like muscular ridges in the atrial walls, particularly prominent in the right atrium. They enhance atrial contraction, increasing blood flow into the ventricles efficiently during systole.

E. Chordae tendineae: These are thin, fibrous cords connecting atrioventricular valve leaflets to papillary muscles. They prevent valve prolapse during ventricular contraction, maintaining proper closure and unidirectional blood flow from atria to ventricles.

F. Right atrium: It is located on the superior right side of the heart and receives deoxygenated blood from the superior vena cava, inferior vena cava, and coronary sinus. It forms the right border of the heart. Physiologically, the right atrium functions as a receiving chamber that collects systemic venous blood and delivers it through the tricuspid valve into the right ventricle during atrial contraction.

G. Bicuspid valve: Also called the mitral valve, it is located between the left atrium and left ventricle. It prevents backflow into the atrium during ventricular contraction, ensuring efficient systemic circulation.

H. Fossa ovalis: This is a depression in the interatrial septum, the remnant of the fetal foramen ovale. It allowed blood to bypass the fetal lungs and normally closes after birth.

I. Left ventricle: The left ventricle pumps oxygenated blood into the aorta under high pressure. Its thick muscular wall enables strong contractions necessary to sustain systemic circulation throughout the body.

J. Interventricular septum: This thick muscular wall separates the left and right ventricles. It prevents mixing of oxygenated and deoxygenated blood and contributes to the contractile force of ventricular systole.

A. Both ventricles: Stroke volume (SV) is the volume of blood ejected by a ventricle during a single contraction, measured from end-diastolic volume minus end-systolic volume. The left ventricle pumps blood into systemic circulation, while the right ventricle pumps blood into the pulmonary circulation, making SV a measure relevant to both ventricles.

B. Left ventricle: The left ventricle pumps oxygenated blood into the aorta for systemic circulation. While left ventricular SV is often emphasized clinically due to systemic perfusion, stroke volume is conceptually defined for both ventricles, not exclusively the left.

C. Right ventricle: The right ventricle ejects deoxygenated blood into the pulmonary trunk for gas exchange in the lungs. Like the left ventricle, it contributes to the stroke volume, so SV is not limited solely to the right ventricle.

D. Both atria: The atria function as filling chambers that contribute to ventricular preload by delivering blood through the atrioventricular valves. While atrial contraction assists ventricular filling, stroke volume specifically refers to blood ejected from the ventricles, not the atria.