The heart conduction system

1. Lloyd Dean
The Heart

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the Aortic and
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16. Cardiac Output
What is it?
The amount, or volume, of blood
pumped by the heart per minute (mL
blood/min)
Heart rate and Stroke Volume make this
up
Heart rate (HR) – beats per minute
Stroke Volume (SV) – Millilitres (mL)
of blood pumped out with each beat.
Cardiac Output = HR x SV
An average person has a resting
heart rate of 70 beats a minute
and a resting stroke volume of
70mL/beat
Work out their cardiac output
CO = HR x SV
CO = 70 x 70
CO = 4900 mL/minute

17. Conduction System
The hearts atria, and then ventricles, need to contract simultaneously
Conduction system includes several components;
Sinoatrial (SA) node – Found in the myocardium at the top of right atrium
 SA node is commonly know as the heart’s pacemaker
Each electrical impulse travels through the muscle fibres of the atria and
ventricles, causing them to contract
Atrioventricular (AV) node delays the electrical impulse to allow the atria to
contract and empty all blood
AV node is an electrical relay station that sends an impulse through the
ventricles along special fibres called “His-Purkinje” fibres.