Blood allows all human body organs to receive oxygen (02) and the nutrients it needs for them to work properly. Blood also removes carbon dioxide (C02) and other waste from these organs.


A pump and some pipes

Blood circulation requires a pump and some pipes.

The heart is the pump and the blood vessels are the pipes, which when put end-to-end extend into a network of some 100,000 km.


The source of blood pressure

When the heart contracts, it expels a quantity of blood into the aorta. This flow of blood into the bloodstream creates tension or blood pressure.


Pressure in the pipes

The blood pressure is like the water pressure in the pipes of your house.

It makes it possible to have water supply everywhere in the house on any floor. 



The pressure makes the blood circulate in the body

In our body, the pressure is what makes the oxygenated blood travel in the arteries.  Blood is propelled from the heart to the organs (brain, kidneys, digestive tract, muscles), then it returns by the veins to be oxygenated by the lungs again.




The two numbers of the blood pressure

The blood pressure is made up of two values, two digits commonly called the large number and the small number.

As the heart beats in a cyclic way, the large number represents the strongest pressure exerted by the blood on the arteries at the time of the heart contraction. It is the systolic pressure.

The small number represents the pressure which remains in the arteries between the contractions. It is the diastolic pressure.


The blood pressure varies constantly

Blood pressure constantly varies from one day to another but also from one time of the day to another.

It is higher during exercise, physical work or periods of stress. It is lower while sleeping. 


Circadian cycle

Our body has a biological clock located in the brain. It is responsible for the cycles of daily hormonal release. This rhythmic pattern is adjusted with landmarks from our environment. These landmarks are mainly the alternation of day and night.

By the end of the night, around 4 to 6 o'clock in the morning, the body is getting ready for the day. In other words, it is at this time that some hormones are in higher concentrations in the blood.

The secretion of cortisol, the cortisone of our body, causes an increase in our blood pressure while we still sleep peacefully.

It is believed that this rise in blood pressure would be associated with the occurrence of heart attacks in the morning.


The heart under the influence of hormones

The heart, influenced by hormone secretion, reacts to all our emotions. It is thus normal that blood pressure varies from one moment to another since we are alive!


The tensiometer

The device used to measure the blood pressure is a tensiometer.

This device usually displays 3 numbers.


Here is an example

Your device indicates 130-80, 72. The first number is your systolic blood pressure, 130 mm Hg (millimetres of mercury). The number 80 indicates your diastolic blood pressure, which is 80 mmHg. The last number represents your heart rate, 72 beats per minute.


How to measure your blood pressure at home

It is preferable to take your blood pressure on a regular basis. Record your values on a piece of paper that you will bring to your doctor.

You should make your measurements during the week preceding an appointment with your physician.


Optimal conditions.

Sit comfortably. Make measurements after 5 minutes of rest and more than 30 minutes after a physical activity.

It is necessary to wait one hour after drinking a coffee or any drink containing caffeine (tea, soft drinks), or after ingesting a stimulating substance like chocolate.

It is necessary to wait 2 hours after a meal because the digestion process increases blood circulation.

Use the washroom if you need to before taking your blood pressure. A full bladder raises the blood pressure.



Measurement must be taken twice a day.

Two measurements are made in the morning, a few minutes apart.

The morning measurement must be done before you take your medication, your coffee or your breakfast.

Two measurements are made at night before going to bed, a few minutes apart.

You must note the two measurements taken each time, even those which seem too high or too low.

Once the day is over, calculate the average of these four values.


The average of the week is a good estimate

The average of the measurements of the last 6 days before an appointment, gives a good estimate of what is really the values of your blood pressure.


Read: Understanding high blood pressure