What is the relationship between the cardiac cycle and an ECG? What is isovolumetric contraction? When does it begin and end?

Expert Answers

An illustration of the letter 'A' in a speech bubbles

The human heart's cardiac cycle is regulated by key electrical events, namely by muscle cells at points called the sinoatrial and atriovencular (or SA and AV) "nodes." The SA node is calibrated to fire at between 60 and 100 beats per minute (BPM), which is the healthy range for a resting heart rate. When it is excited, it induces atrial contraction . The AV node fires at between 40 and 60 BPM, and slows the electrical impulses sent from the SA node to ensure that each...

(The entire section contains 233 words.)

Unlock This Answer Now

Start your 48-hour free trial to unlock this answer and thousands more. Enjoy eNotes ad-free and cancel anytime.

Start your 48-Hour Free Trial
Approved by eNotes Editorial Team