What is blood pressure, and how does it relate to hypertension?

Blood pressure is the force of the blood pushing against the artery walls. The force is generated with each heartbeat as blood is pumped from the heart into the blood vessels. The size and elasticity of the artery walls also affect blood pressure; each time the heart beats, pressure is created inside the arteries. When your blood pressure is high, it causes hypertension.

When blood is pumped out of the heart into the arteries, the pressure is at its greatest. The pressure falls in the arteries when the heart relaxes between beats. Two numbers are recorded when measuring blood pressure:

  • Systolic pressure, the top number, refers to the pressure inside the artery when the heart contracts and pumps blood through the body.
  • Diastolic pressure, the bottom number, refers to the pressure inside the artery when the heart is at rest and is filling with blood.

Both systolic and diastolic pressures are recorded as "mm Hg" (millimeters of mercury), representing how high the mercury column in the blood pressure cuff is raised by the pressure of the blood.

Levels of hypertension

High blood pressure, also known as hypertension, increases the risk of heart attack and stroke. With hypertension, the arteries may have an increased resistance to the flow of blood, causing the heart to pump harder to circulate the blood. Usually, hypertension has no signs or symptoms, but you can check your blood pressure yourself or have it checked by your physician to know if you have hypertension.

The National Heart, Lung, and Blood Institute (NHLBI) of the National Institutes of Health (NIH) has determined two levels of high blood pressure for adults:

Stage 1

  • 140 mm Hg to 159 mm Hg systolic pressure—top number
  • 90 mm Hg to 99 mm Hg diastolic pressure—bottom number

Stage 2

  • 160 mm Hg or higher systolic pressure
  • 100 mm Hg or higher diastolic pressure

Note: These numbers are only to be used as a guide; consult your physician with any concerns.

What are the risk factors for high blood pressure?

  • People who have diabetes, gout or kidney disease
  • African Americans, particularly who live in the southeastern US
  • People in their early to middle adult years; men in this age group have higher blood pressure more often than women in this age group
  • People in their middle to late adult years; women in this age group have higher blood pressure more often than men in this age group (more women have high blood pressure after menopause than men of the same age)
  • Middle-aged and elderly people; more than half of all Americans 60 and older have high blood pressure
  • People with a family history of high blood pressure/hypertension
  • People consuming a high-salt diet
  • Overweight people
  • Heavy drinkers of alcohol
  • Women who are taking oral contraceptives
  • People with depression

How is hypertension controlled?

  • Take prescribed medication as directed by your physician
  • Choose foods that are low in salt (sodium)
  • Choose foods low in calories and fat
  • Choose foods high in fiber
  • Maintain a healthy weight or lose weight, if already overweight
  • Limit serving sizes
  • Increase physical activity
  • Reduce or omit alcoholic beverages

Sometimes daily medication is needed to control hypertension. If you have hypertension, check your blood pressure regularly, and see your physician to monitor the condition.