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You may hear the word “hypertension” a lot: in a medical clinic, on the news and in passing conversation. If you’ve ever wondered what it really means, read on.

Simply put, hypertension means high blood pressure, a condition that people of all ages, races and ethnicities can develop. Blood pressure is the measurement of blood pushing on the wall of an artery during two phases:

• when the heart contracts or squeezes blood out of its chambers during each heartbeat, and
• when the heart relaxes in between beats.

There are two numbers—such as 120/80 mmHg—in a blood pressure reading, indicating the systolic (first number) and diastolic (second number) pressures. Systolic blood pressure refers to when the heart contracts and diastolic blood pressure refers to when the heart relaxes.

In people with hypertension, one or both of their measured blood pressures are higher than normal. When systolic blood pressure is above 130 mmHg and/or diastolic blood pressure is above 90 mmHg, a person may have hypertension. When systolic blood pressure is high, the heart must work harder than normal to push blood from its chambers into the arteries. Conditions that affect the aorta—the largest artery in the body, which carries blood away from the heart—can raise systolic blood pressure. Cholesterol buildup in the aorta or narrowing of the aortic valve, called aortic stenosis, means the heart must generate more pressure to expel blood into the aorta. The increased pressure raises systolic blood pressure. Arteries that become stiff or narrowed from diabetes, smoking or high cholesterol can cause the diastolic blood pressure to increase as blood pushes against the hardened walls of the blood vessel.

Hypertension not only makes the heart work harder, but it also may lead to other complications, such as stroke, heart failure, memory loss, organ damage and decreased blood flow to vital organs. The good news about high blood pressure is that it’s treatable—and in many cases, preventable. Limiting the amount of fat and sugar in your diet, watching your salt intake, exercising and taking medications when necessary can help manage hypertension.

Jessica C. Taylor, PhD, is a cardiovascular physiologist who enjoys sharing physiology with the general public through writing.