Blood Pressure - The Basics

Your heart pumps blood around your body through a network of tubing called arteries and capillaries and then back to your heart via your veins. Blood pressure is the force of the blood pushing against the walls of the arteries as the heart pumps.

As your heart contracts it pushes blood into your arteries and this causes an increase in pressure, and the highest pressure is known as the systolic pressure. As your heart relaxes and refills with blood, the pressure in your arteries falls and this is known as diastolic pressure. When blood pressure is measured in your arm, both of these pressures are measured.

Blood pressure is always given as  two numbers, the systolic and diastolic pressures. Both are important. Usually they are written one above or before the other, such as 120/80 and expressed in units of millimetres of mercury (mmHg). The systolic pressure is the first or top number, and the diastolic pressure is the second or bottom number. If your blood pressure is 120/80, you say that it is "120 over 80".

Blood pressure can vary over a wide range. For instance, the top pressure when the heart contracts (systolic) can vary from 90 to 240 mmHg and the bottom pressure when the heart relaxes (diastolic) can vary from 40 to 160 mmHg.

Your blood pressure varies by large amounts, depending on what you are doing during the day. The lowest blood pressures occur when you are asleep or if you relax all your muscles. Standing up, exercising, anxiety, and nervousness can each cause an increase in blood pressure. In a single day your blood pressure may vary by 30 to 40 mmHg systolic with similar proportionate changes in diastolic pressure. This is why it is important to have your blood pressure measured under the same conditions every time.

For most of your waking hours, your blood pressure stays pretty much the same when you are sitting or standing still. Ideally, your blood pressure should be 120/80 or lower when relaxed.

 When the level stays high, such as 140/90 or higher, you have a condition called high blood pressure or hypertension. With high blood pressure, the heart works harder to pump blood through your arteries, your arteries take a beating from having the blood forced into and through them, and your risks of a stroke, heart attack, and kidney problems are increased.

Hypertension can be treated. Mild cases of hypertension can be treated through behavior modification like changing diet, increasing exercise, losing weight, and so on. More severe cases of hypertension require medications like diuretics and beta blockers. Diuretics rid the body of excess fluids and salt. Beta blockers reduce the heart rate and the heart's output of blood. This will reduce your risk of developing heart and brain problems that might otherwise occur if your blood pressure is not treated.

To help you control blood pressure, it's important to understand what blood pressure is, what causes it to rise, what the risk factors are, and how you can prevent it.

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