Which sequence correctly describes the path of blood through the heart and lungs?

• A. Right Ventricle; Right Atrium; Lungs; Left Atrium; Left Ventricle.
• B. Right Atrium; Right Ventricle; Lungs; Left Atrium; Left Ventricle.
• C. Left Ventricle; Left Atrium; Lungs; Right Atrium; Right Ventricle.
• D. Left Atrium; Left Ventricle; Lungs; Right Atrium; Right Ventricle.

Answer: (B)

Blood flows through the heart in a single, ordered circuit that keeps deoxygenated blood separate from oxygenated blood and channels it to the lungs before sending it out to the body. Deoxygenated blood returns to the heart at the right atrium, moves into the right ventricle, is pumped to the lungs to pick up oxygen, returns to the heart via the pulmonary veins into the left atrium, then goes to the left ventricle to be sent out to the body.

The sequence that starts with the right atrium, then the right ventricle, then the lungs, then the left atrium, and finally the left ventricle matches this flow exactly.