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Cardiology Teaching Package

A Beginners Guide to Normal Heart Function, Sinus Rhythm & Common Cardiac Arrhythmias

Normal Function of the Heart

The simplest way to describe the heart is as a "pump". Quite often doctors and nurses take the analogy further and talk to patients about their "plumbing". This analogy is reasonably accurate.

The role the heart plays in the cardiovascular system is similar to the role played by the pump in your central heating system. The heart pumps blood through the arteries and veins to organs, muscles and tissues, just as the central heating pump forces hot water through the pipes to the radiators.

But that is where the analogy ends.

The cardiovascular system is made up of : heart; lungs; arteries and veins, and it is under the control of the autonomic nervous system (sympathetic and parasympathetic). In a healthy individual with a healthy heart, heart rate is dictated by the body's needs. If an individual is resting then organs, muscles and tissues require a reduced amount of blood and oxygen. The result of this is a reduction in blood pressure and a slowing down of heart rate and respirations.

When the individual becomes active then the organs, muscles and tissues require an increasing amount of blood and oxygen, resulting in raised blood pressure and an increase in heart rate and respirations. These responses are all involuntary, under the direct control of the autonomic nervous system. If the individual remains reasonably healthy with no cardiac complications then the cardiovascular system will continue to work just like this for life.

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