Introduction to Heart

2.2 Heart Function

The heart is an organ in the human body for providing blood and oxygen. It is divided into 2 halves containing four chambers, as shown in Figure 1. As seen, left and right atria are upper chambers, while the left and right ventricles are the lower chambers. There are fibrous, non-conductive tissues for joining the atria to the ventricles to keep the ventricles electrically isolated from the atria. In addition, the heart contains veins called the superior and inferior vena cava for receiving the oxygen-poor blood into the right atrium. In order to pump the blood to the lung, the right atrium and the right ventricle cooperate together. The blood is forced into the right ventricle by the right atrium. In order to oxygenate the blood, the right ventricle then pumps it to the lungs. The oxygen-enriched blood received from the lung by the left atrium and the left ventricle circulates to the rest of the body (Adlam and Hampton, 1997).

Regular electrical impulses in the heart are spontaneously generated by the node called heart Sinoatrial (SA). The electrical impulses help the heart conduction system to initiate the contraction of the myocardium. In the heart function, there is a process called depolarisation that is because of the propagation of an electrical impulse to through the heart tissue. The depolarisation of the heart muscles causes generation of a strong ionic current (Silver, 2002). The generated current provides a voltage drop by flowing through the resistive body tissue. The electrical impulse flows to the atrial myocardium as a result of atrial depolarisation. The electrical impulse is spread throughout the ventricular myocardium as the result of ventricular depolarisation.

Figure 1.

The heart conduction system (Adlam, D., and Hampton, R.,1997)