Multiple choice

_____ block backflow of blood.

  1. Veins

  2. Arteries

  3. Valves

  4. Capillaries
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Heart valves are one-way gates that prevent backflow of blood. The atrioventricular valves (tricuspid on right, mitral on left) prevent backflow from ventricles to atria. Semilunar valves (pulmonary and aortic) prevent backflow from arteries back into ventricles. This ensures blood flows only in the forward direction.

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