Blood Pressure Basics

How does blood pressure work

The Basics of Blood Pressure
Systolic Pressure and Diastolic Pressure Described

Ever wonder what that squeeze machine is doing and what the nurse is listening to when taking blood pressure? Here are the basics.

There’s plenty of hype explaining the dangers of blood pressure and how it’s bad for you, but do you really know what high blood pressure means? We’ve all been in the doctor’s office, and the first thing the nurse does is take this arm covering apparatus, place it over your arm, and squeeze this ball until it inflates to numbing sizes. There’s more to a blood pressure exam than just the uncomfortable feeling of an inflatable tube.
Systolic Pressure

Systolic pressure is the moment your heart squeezes the blood into the blood vessels. There are a lot of elements that relate to systolic pressure, and these are also important to your heart’s health. For instance, if your heart rate is too fast, the heart does not have enough time in diastole to fill the ventricles. This results in poor blood circulation in the body. Systolic pressure is the primary way for your organs and tissue to receive nutrients and oxygen, but it works in conjunction with diastolic pressure.

Because systolic pressure is the intense part of the blood pressure readings, it is the largest number when reading blood pressure results. For instance, a normal numerical value for systolic pressure is 120. However, this number varies for each individual.

Diastolic Pressure

Diastolic blood pressure is when the heart relaxes after systole. During diastole, the heart receives the blood from the veins to prepare for oxygenation and circulation back into the body. Diastolic pressure is the low number in the blood pressure reading. Normal diastolic pressure is about 80 mmHG. This number may vary with age, smokers, and people with cardiovascular disease.
How Does the Blood Pressure Test Work?

What makes this test so interesting is the basic techniques it uses. The nurse pumps air into the sphygmomanometer, and it squeezes blood vessels into the arm to where blood cannot pass. As the nurse relieves the arm from the pressure, the heart begins to return blood pressure to normal. As the blood squeezes past the blockage, it bounces against the arteries which cause a noise. The noise pulses as the heart squeezes and pushes the blood past the blockage.

The point at which the noise is heard is recorded as the systolic pressure. As the arteries continue to fill with blood, the point when the noise is no longer heard is recorded as the diastolic pressure. This is then translated into the simple numbers patients are used to seeing in their medical charts.

What the Numbers Mean

If your blood pressure is less than 120/802:

  • Your blood pressure is normal

If your blood pressure is between 120/80 and 140/902:

  • You’re at risk for high blood pressure. Lifestyle modifications are important and should be recommended by your doctor or healthcare professional

 If your blood pressure is:

140/90 and above
130/80 and above
you have diabetes or chronic kidney disease2:

  • Your blood pressure is high. Lifestyle modifications and high blood pressure medication are important and should be recommended by your doctor or healthcare professional