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The right atrium receives blood returning from the body and functions as a low-pressure reservoir. It has the lowest pressure of all four chambers.

The right ventricle pumps blood to the lungs, which is a low-pressure system. Although its pressure is higher than the right atrium, it is much lower than the left ventricle.

The left ventricle must generate high pressure to pump blood through the systemic circulation. Systemic vascular resistance is much higher than pulmonary resistance, requiring the left ventricle to work harder. Because of this, the left ventricle has the highest pressure of all four chambers. This pressure difference explains why septal defects typically cause left-to-right shunting initially.

Volume of blood returning to the heart refers to venous return, which affects preload, not stroke volume. Preload is a determinant of SV, but it is not the definition of SV.

Ability of the cardiac muscle to act as an efficient pump describes contractility, which influences SV, but is not stroke volume itself.

Resistance the ventricles pump against when ejecting blood describes afterload, such as systemic vascular resistance, which affects SV, but is not stroke volume.T

Delaying impulses to keep ventricles from contracting too quickly is the function of the atrioventricular (AV) node, which slows the conduction to allow ventricular filling.

Controlling the heart rate rhythm is primarily the sinoatrial (SA) node, the heart’s natural pacemaker.

While Purkinje fibers rapidly transmit impulses, the most precise description of their function is that they conduct impulses into the ventricular muscle, not just “resume rapid conduction.” The Purkinje fibers don’t “resume” conduction; they are the final rapid conduction pathway.

Carrying oxygenated blood from placenta to fetus describes the umbilical vein, which brings oxygenated blood from the placenta to the fetus, not the foramen ovale.

Carrying deoxygenated blood from fetus to placenta describes the umbilical arteries, which return deoxygenated blood from the fetus to the placenta. The foramen ovale does not carry blood to the placenta.

Connecting pulmonary artery to the aorta describes the ductus arteriosus, another fetal shunt that bypasses the lungs by connecting the pulmonary artery to the aorta. The foramen ovale, in contrast, shunts blood atrial-to-atrial, not arterial-to-arterial.