Bill Isaacs, age 11, of Tulsa, Okla., for his question:

WHAT IS HIGH AND LOW BLOOD PRESSURE?

Medically speaking, the term blood pressure refers to a reading of pressure in the large artery in a person's left arm. Two measures are taken: systolic pressure, or that which is pumped by the heart during contraction, and diastolic pressure, the force when the heart is relaxing.

Normal highs and lows vary, depending on the person and  his age. It's like a shoe size. You can't determine normal without considering many factors.

Normal systolic in an adult male  nay vary between 100 to 150, while diastolic range is 60 to 88. A doctor, knowing many factors that have to be considered, is the one to tell if the pressure is too high or too low.