What prevents backflow of blood during heart contraction?
- AThick walls of the atria
- BThick muscular walls of the ventricles
- CHeart valves
- DNone of the above
Show answer and explanation
Correct answer: (c) Heart valves
Explanation
Heart valves let blood flow in one direction only and close to stop it flowing back when the chambers contract.
The atria have thin walls because they only pass blood to the ventricles; the ventricles have thick muscular walls because they pump blood to the body.