Distinguish between myogenic and neurogenic heart. Explain the working of human heart.

In myogenic heart the cardiac impulse is initiated by a specialized cardiac tissue
called nodal tissue. Whereas in neurogenic heart the heart beats are initiated by nervous stimulations.
Human heart is myogenic. Working ofhuman heart involves regular and rhythmic heart beats or cardiac rhythms. Each heart beat consists of alternate contraction and relaxation ofmuscular walls. The phase ofcont action ofthe heart wall is known as systole and that of relaxation is known as diastole. Systole takes place in two successive stages, namely auricular systole and ventricular systole. Since diastole is more or less simultaneous in all the chambers it is known as joint diastole.
During auricular systole deoxygenated blood from the right auricle is forced into the right ventricle and oxygenated blood from the left auricle is forced into the left ventricle. During ventricular systole deoxygenated blood from the right ventricle is pumped into the pulmonary artery for oxygenation in the lungs and oxygenated blood from the left ventricle is pumped into the aorta for distribution all over the body. Back flow ofblood to the auricles is prevented by auriculoventricular valves. Dur- ing diastole the chambers of the heart dialate for refilling.