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The Cardiac Cyle

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Introduction

The Cardiac Cyle The Cardiac cycle is activated by an electrical stimulus called the cardiac impulse. This stems from a small mass of tissue found in a region of the right atrium, called the Sino atrial node or pacemaker. The electrical stimulus generated by the Sino-atrial node spreads out into the walls of the atria causing their contraction, in other words atrial systole. A band of fibrous tissue splits the atria from the ventricles, and stops the impulse passing straight on to the ventricles. ...read more.

Middle

Impulses from these cause the walls to contract. The Sino-atrial node kicks off systole and this is followed a fraction later by ventricular systole, which because of the nature of the conduction system begins at the apex of the ventricles. Once systole has finished, diastole begins. The transfer of blood through the heart is directed by the heart valves, the opening and closing of which in turn is controlled by the adjustments in blood pressure that happen within the chambers of the heart. ...read more.

Conclusion

It is located in the upper part of the heart above the left and right atriums. Atrio-ventricular node- a specialized bundle of muscle tissue. It is located in the floor of the right atrium. Bundle of His- Specialised bundles of nerve fibre found in the septum that form part of the conduction system of the heart. Purkinje Fibres- Specialised nerve fibres found in the ventricles that form part of the conduction system of the heart. ...read more.

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