Which of the following represents the correct sequence of blood flow through the heart starting from the right atrium?

• A. Right atrium  tricuspid valve  right ventricle  aortic valve  aorta  systemic circulation  pulmonary artery  lungs  pulmonary veins  left atrium
• B. Right atrium  bicuspid valve  left ventricle  aortic valve  aorta  systemic circulation
• C. Right atrium  tricuspid valve  right ventricle  pulmonary valve  pulmonary artery  lungs  pulmonary veins  left atrium  mitral valve  left ventricle  aortic valve  aorta  systemic circulation.
• D. Right atrium  pulmonary valve  right ventricle  mitral valve  left atrium  tricuspid valve

Answer: (C)

Blood moves through the heart in a continuous loop that takes it from the body to the lungs for oxygen and back out to the body again. Starting in the right atrium, blood passes through the tricuspid valve into the right ventricle, then through the pulmonary valve into the pulmonary artery and onward to the lungs. After picking up oxygen, it returns through the pulmonary veins into the left atrium, moves through the mitral valve into the left ventricle, and then goes through the aortic valve into the aorta to reach systemic circulation. This sequence correctly reflects the separation of pulmonary and systemic circuits and the order of the heart valves. The other options misplace valves or omit the pulmonary circulation, which makes them inconsistent with how blood actually flows through the heart.