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  How Does the Human Heart Work?

This describes the anatomy or structure of the human heart and circulation of blood to the body. The heart is a powerful muscular organ. It consists of 4 chambers – the right side of the heart separated from the left by a muscular wall – the septum, and the upper and lower chambers (atria and ventricles) are separated by valves. With each heart contraction, the blood is pumped out from the left ventricle to the whole body to supply oxygen and nutrients to all the tissues of the body.

This ‘used’ or ‘deoxygenated’ blood then returns to the right side of the heart to the right Atrium and ventricle. From the right ventricle, the deoxygenated blood goes to the lungs where it receives fresh oxygen (re-oxygenated). This then returns to the left side of the heart and the circulation continues.

How Do Heart Valves Work?

The heart has 4 valves:

  1. The Tricuspid Valve which separates the right Atrium from the right Ventricle.
  2. The Pulmonary Valve which separates the right Ventricle from the Pulmonary Artery.
  3. The Mitral Valve which separates the left Atrium from the left Ventricle and
  4. The Aortic Valve which separates the left Ventricle from the Aorta.

Each valve is like a one way door which keeps the blood flow in one direction. The valves are made up of leaflets. These leaflets open to allow blood to flow through the door to prevent blood flowing backwards. The opening and closing of the valves is controlled by pressures in the chambers.

What is Coronary Artery Disease (CAD)?

The Coronary Arteries supply blood to the heart muscle to provide the necessary oxygen and nutrients to the heart muscle.

CAD occurs when there is obstruction to the flow of blood in the Coronary arteries when there is a build-up of cholesterol plaque in the artery wall. This result is a ‘heart attack’.

What controls the heart rate?

There is an electrical system or ‘battery’ in the heart which controls the heart beat and rhythm of the heart.

This ‘battery’ starts at the sinoatrial (SA) node and causes the heart to contract.

The electrical impulses travel to the AV node and down the bundles.

Sometimes, the heart rate can change based on external factors like diet, exercise, stress and hormonal factors.