It will do you good to know what is blood pressure and have some basic knowledge about it. It could be high (hypertension) or it may be lower than normal (hypotension). Both these conditions are undesirable.

Reason? According to the Centers for Disease Control and Prevention (CDC):

  • About 70 million American adults (29%) have high blood pressure —that’s 1 in every 3 adults
  • About 1 in 3 American adults has prehypertension— readings that are higher than normal—but not yet in the hypertensive range.
  • Only about half (52%) of people with high blood pressure have their condition under control.
  • High blood pressure was a primary or contributing cause of death for more than 360,000 Americans in 2013—that’s nearly 1,000 deaths each day.

High blood pressure, also called hypertension, is known as the silent killer. Most of the time, it lies undetected while it continues doing serious damage inside your body. It is only when its serious and debilitating complications set in, that your diagnosis is pronounced.

What is blood pressure?

Blood pressure is the pressure exerted by the blood on the walls of the arteries during its flow through the arteries. When your doctor measures it, he gets two readings. One reading indicates the pressure when the heart is contracting and the other reading indicates the pressure of the blood when the heart is relaxing or expanding.

When the heart is contracting (systole), the blood is being pumped out of the heart and, therefore, the pressure will naturally be higher than when it is expanding and the blood is passively entering the heart (diastole).

Systolic blood pressure

The pressure in the arteries is higher at the time of contraction of the heart and is called systolic blood pressure. This is the pressure exerted on the walls of the arteries.

Diastolic blood pressure

The pressure of blood is lower at the time of the relaxation of the heart and is called diastolic blood pressure. This indicates the pressure against which the heart has to pump blood.

What are the normal blood pressure readings?

The normal systolic blood pressure is 100 to 140 mm of hg and the normal diastolic pressure is 60 to 90 mm of hg  (hg stands for mercury which is used in the standard blood pressure instrument).

Blood pressure ranges, therefore, from the higher side of the normal to the lower side of the normal. Within this range, it is considered normal or good, or healthy. It is important to have and maintain it within these normal levels.

 How is it measured?

Blood pressure is measured by placing the stethoscope on the inner and front side of the elbow, where the brachial artery is situated, and with the help of the blood pressure machine called the sphygmomanometer. Digital monitors are also available.

Many a time, due to various reasons, the systolic or the diastolic pressure may increase or decrease and cause certain complications, which may be serious and even lethal. It is, therefore, necessary to have your blood pressure checked regularly, especially after the age of 35 years or earlier.

Systolic Pressure above 140mm hg or diastolic above 90 mm hg indicates a rise in the pressure and is called hypertension. A fall in this pressure below the normal level is called hypotension. Both these conditions when diagnosed, have to be treated consciously.

Why maintain normal blood pressure?

There are various causes why your blood pressure is high. It may present some signs and symptoms, or sometimes it may not. If undiagnosed, it may increase to a point where it can cause serious complications like chronic heart disease, stroke, and kidney failure, hemiplegias, among other things. It should also be noted that high readings can also be found in people of younger age groups.

High pressure can be due to some pathological reason like kidney disease or a tumor, or it may occur without any cause or reason. High B.P. that occurs without any reason is called essential hypertension.

Low blood pressure or hypotension occurs due to some other illness and can be an indication of some life-threatening illness. It may be due to various causes and may present some symptoms and complications. 

Blood pressure chart

Many blood pressure charts are available, which give a picture of the normal, high, and low readings. The following chart gives a comprehensive idea of its various readings.

Upper limit (systolic) in mm Hg  Lower limit (diastolic) in mm Hg Status
Below 120 Below 80 Normal blood pressure .
Between 120-139 Between 80-89 Prehypertension .
Between 140-159 Between 90-99 Stage 1 hypertension
160 or higher 100 or higher Stage 2 hypertension .