The heartbeat

What is a heartbeat? how does a heartbeat work?

The heartbeat sequence has three phases:

• diatole
• atrial systole, and
• ventricular systole

The timing of these phases must be accurately maintained, regardless of how slowly or rapidly the heartbeat is.

The first heartbeat sequence phase: the diatole

Diastole

• A: Right atrium relaxes and deoxygenated blood flows in
• B: Left atrium relaxes and oxygenated blood flows in
• C & D: Both right and left ventricles relax

The second heartbeat sequence phase: the atrial systole

Atrial Systole

• A: Right atrium contracts and pumps blood into right ventricle
• B: Left atrium contracts and pumps blood into left ventricle
• C: Tribuspid valve opens
• D: Mitral valve opens
• E & F: Both left and right ventricles dialate

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