Hypertension, a condition in which blood pressure is persistently elevated (it stays high for a long period of time). Blood pressure is a measure of the pressure of the blood against the blood vessel walls. Persistent high blood pressure puts undue stress on the heart, blood vessels and other organs because your heart must work much harder to maintain adequate blood flow to your body.
There are two ways to classify high blood pressure: Essential hypertension and Secondary hypertension. With essential hypertension the cause can be a number of factors including a narrowing of the arteries, too much blood, or the heart beating faster or more forcefully than what is normal. Secondary hypertension is caused by another problem in the body, for example kidney disease. When the true cause if found and treated the hypertension will disappear.
Measuring blood pressure is done with two numbers, the first number (systolic) is the pressure of the blood against the artery walls when the heart pumps blood to the organs. The second, lower number (diastolic) is the pressure against the artery walls when the heart relaxes between beats. A reading of 120/80 is considered normal.
A reading consistently at 140/90 would be consider hypertension or high blood pressure.
Low blood pressure is a condition where the blood pressure that is too low. For some young or small people, a blood pressure reading of 90/70 or even 80/60 is perfectly normal and healthy. When their blood pressure is really too low, people feel dizzy or light headed every time they stand up, or they always feel tired and lacking energy.