Multiple choice

Which among the following does not characterise a mammalian heart?

  1. A single heartbeat lasts about 0.8 seconds.

  2. The impulses are delayed for about 0.1 second at bundle of HIS.

  3. The SA node generates electrical impulses.

  4. Few cardiac cells can contract without any signal from the nervous system.

  5. The heart is effectively a syncytium.
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The atrioventricular node, located in the wall between the right atrium and the right ventricle. Here, the impulses are delayed for about 0.1s before spreading to the walls of the ventricle.

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