Systole: A Blood Pressure Reading

Systole, is the top number of a blood pressure reading. When listening with your stethoscope is the first heart beat you hear. Contraction of the heart and ventricles. During systole, blood is forced into the aorta and pulmonary artery.

Diastole, the bottom number of a blood pressure reading. Listening with your stethoscope is the last and most faint beat you hear when obtaining blood pressure. It's the relaxation and dilatation period of the heart chambers and ventricles, during so they are filled with blood.