When the ventricles contract, the atrioventricular valves

  1. stay open
  2. open to let blood into the atria
  3. close the aorta
  4. close to stop blood flowing back into the atria
Answer

D) close to stop blood flowing back into the atria

AV valves close during ventricular contraction. O Level Biology · Topic 11 Transport in Humans · 11.2 Heart

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