The heart

Atrioventricular valves open, blood is forced into ventricles

Av valves close to prevent backflow

Semilunar valves open, blood flows into arteries

All chambers relax, pressure of blood causes valves to close preventing backflow into ventricles.

Sino atrial node, myogenic started by the muscle. Sets the pace sweeps to atrial walls makes it contract reaches atrioventricular node, delays impulse recieve signal after atria.

Moves to purkynes tissue, sweeps upwards to the ventricle walls, it contracts, ventricles then relax and the signal begins all over again.

A healthy heart has consistent waves, a small p wave, a dip in the q wave, and elevated R wave, a dip in the s wave and a small elevation in the T wave.

A heart attack shows an elevation of S AND T waves

Atrial fillibration, or an uncoordinate heart is shown by an unclear P wave

An increase in the thickness of the wall of the heart is show by deep S waves.