High pressure usually refers to systolic blood pressure and low pressure usually refers to diastolic blood pressure. Human blood pressure includes both high and low pressure. Systolic blood pressure is the pressure within the aorta that rises when the heart contracts and reaches its highest value in the mid-systole of the heart, when the blood pressure is called systolic blood pressure. When the heart is diastolic, the lowest value of arterial blood pressure reached at the end of cardiac diastole is called diastolic blood pressure due to a decrease in pressure within the aorta. Normal adults have a low pressure of 90-140 mmHg and a diastolic pressure of 60-90 mmHg. When the systolic pressure exceeds 140 mmHg or the diastolic pressure exceeds 90 mmHg, it is called hypertension, and when the systolic pressure is lower than 90 mmHg or the diastolic pressure is lower than 60 mmHg, it is hypotension.