Question

Choose the correct answer from the alternatives given.
In normal heart action:

• A. right atrium and ventricle contract, followed by the contraction of the left atrium and ventricle
• B. two atria contract together, then the two ventricles contract together
• C. right atrium and left ventricle contract, followed by the contraction of the left atrium and right ventricle
• D. all four chambers of the heart contract and then relax simultaneously

Answer 1

The correct option is B two atria contract together, then the two ventricles contract together

Due to one complete cardiac cycle, the two atria contract during the first 0.1 seconds, followed by ventricular systole for 0.3 seconds and finally joint diastole for 0.4 seconds.

So, the correct option is 'Two atria contract together, then the two ventricles contract together'.