the top number is your "systolic" pressure. Normal is 120. Anything over 135-140 is high and should be treated. The "systolic" pressure is the moment after your left ventricle pumps out the blood and is the highest pressure in the heart cycle. High blood pressure can be from many things but often it is the arteries that are no longer complaint. That means when the ventricle pushes the blood into the arteries they normally swell as bit taking some of the pressure. If arterys are "hardend" and dont "swell" then all that blood pushed in has no where to go and hence pressure goes up. High blood pressure over time will cause organ damage (heart, kidneys, liver etc) There are lots of medications for this but diet is important.. no salt especially.
Jassipd is wrong. believe me, I have been to the doctor and er many of times, and they always say the bottom number is the one to worry about. You will notice that when the bottom number is low, you feel great, but when the bottom number is high, you feel like crap. Whatever you do, do not get on prescription meds. I wish someone's would have warned me. All perscription meds are poison. Take natural supplements, exersize, stop eating bad food, stop stressing, smoking and drinking too much alcohol. I did all of those things and was able to get off of all my meds, and now I feel fantastic. Also drink vinegar, drink wheatgrass, fresh beats and take GABA. Wake up and live!