Biology 9700 · AS & A Level · The heart

The heart — practice question

A number of events that occur in a cardiac cycle are given below. 1. The left and right atria contract. 2. The left and right ventricles contract. 3. A wave of electrical activity is carried by the Purkyne tissue. 4. A wave of electrical activity travels through the atrioventricular node. What is the correct order of events after the sinoatrial node releases a wave of electrical activity?

  • A$1 \rightarrow 3 \rightarrow 4 \rightarrow 2$
  • B$1 \rightarrow 4 \rightarrow 3 \rightarrow 2$
  • C$2 \rightarrow 4 \rightarrow 3 \rightarrow 1$
  • D$4 \rightarrow 1 \rightarrow 3 \rightarrow 2$

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