Stroke volume (SV) refers to the amount of blood pumped by which ventricle?

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. During pulmonary circulation: Pulmonary circulation refers to the movement of blood from the right ventricle through the pulmonary trunk to the lungs and back to the left atrium. The tricuspid valve is between the right atrium and right ventricle and does not open or close in response to pulmonary vascular events. Its function is confined to regulating flow between the right atrium and right ventricle.

B. During right ventricular systole: Right ventricular systole occurs when the right ventricle contracts to eject blood through the pulmonary valve into the pulmonary trunk. During this phase, the tricuspid valve should be closed to prevent regurgitation of blood back into the right atrium. Proper valve competence at this time prevents right atrial volume overload.

C. During left ventricular systole: Left ventricular systole involves contraction of the left ventricle and ejection of blood through the aortic valve into systemic circulation. This phase is functionally and anatomically related to the mitral and aortic valves on the left side of the heart. The tricuspid valve on the right side is not involved in left ventricular contraction dynamics.

D. During right atrial systole: Right atrial systole occurs at the end of ventricular diastole when the right atrium contracts to push blood through the tricuspid valve into the right ventricle. The tricuspid valve must be open during this phase to allow forward flow into the right ventricular chamber. Its proper opening ensures adequate right ventricular filling prior to ventricular systole.

E. During atrial diastole: Atrial diastole refers to the relaxation phase of the atria when they are filling with venous blood from the venae cavae. Although the tricuspid valve may be open during part of ventricular diastole due to pressure gradients, atrial contraction is the specific phase that actively requires valve opening for optimal ventricular filling.