What is High Blood Pressure?

First, let’s define high blood pressure.

High blood pressure, also known as hypertension, is when your blood pressure, the force of your blood pushing against the walls of your blood vessels, is consistently too high.

How your blood pressure and circulatory system work

To survive and function properly, your tissues and organs need the oxygenated blood that your circulatory system carries throughout the body. When the heart beats, it creates pressure that pushes blood through a network of tube-shaped blood vessels, which include arteries, veins and capillaries. This pressure — blood pressure — is the result of two forces: The first force (systolic pressure) occurs as blood pumps out of the heart and into the arteries that are part of the circulatory system. The second force (diastolic pressure) is created as the heart rests between heart beats. These two forces are each represented by numbers in a blood pressure reading.

See how high blood pressure can damage your arteries and heart.

The damage starts in your arteries and heart.

The primary way that high blood pressure causes harm is by increasing the workload of the heart and blood vessels — making them work harder and less efficiently.

Over time, the force and friction of high blood pressure damages the delicate tissues inside the arteries. In turn, LDL (bad) cholesterol forms plaque along tiny tears in the artery walls, signifying the start of atherosclerosis.

The more the plaque and damage increases, the narrower the insides of the arteries become — raising blood pressure and starting a vicious circle that further harms your arteries, heart and the rest of your body. This can ultimately lead to other conditions ranging from arrhythmia to heart attack and stroke.

• See how high blood pressure can damage the inside of your arteries.
• See how atherosclerosis takes place.
• See how your heart can become enlarged.
• See an infographic of the consequences of high blood pressure. (PDF)

High blood pressure is a 'silent killer.'

You may not feel that anything is wrong, but high blood pressure could be quietly causing damage that can threaten your health. The best prevention is knowing your numbers and making changes that matter in order to prevent or manage high blood pressure.

Get the high blood pressure fact sheet: English (PDF) | Spanish (PDF)