Systolic pressure (the top number) reflects the force exerted on artery walls when the heart contracts, while diastolic pressure represents metanail complex  the pressure when the heart is at rest between beats. The unit "mmHg" originates from the use of a mercury-filled column in the measurement apparatus. Understanding Optimal Blood Pressure (200 words): Healthy blood fast lean pro reviews pressure levels fall within a specific range. The American Heart Association defines normal blood pressure as below 120/80 mmHg.