Understanding blood pressure

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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

Blood pressure may be compared to the water pressure in the pipes of your house, ensuring that water is available on all floors of your home.

Pressure is what causes blood to flow through the arteries.

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

The 2 digits of blood pressure readings

Blood pressure is made up of 2 values, 2 digits commonly called the top number and the bottom number.

The heart beats in a cyclical manner. The top number measures the force your heart exerts in the walls of your arteries during the contraction of your heart muscle. It is called the systolic pressure. The bottom number refers to the pressure your heart exerts in your arteries in between beats. This is called the diastolic pressure.

Blood pressure varies constantly.

Blood pressure varies greatly on a daily and time of day basis.

It is higher during exercise, physical work and periods of stress. Blood pressure decreases during sleep and goes up again early in the morning.

Circadian cycle

Our body has a biological clock located in the brain. It is responsible for the daily hormonal release cycles. The heart rate adapts to the parameters of its environment, especially that of the alternation between day and night.

By the end of the night, around 4 to 6 o’clock in the morning, the body gets ready for the day. In other words, it is at this time that hormone concentrations in the blood are at their peak.

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

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

The link between hormones and cardiovascular health

Hormones play a leading role when it comes to heart health. When hormones are working properly, they can help prevent heart disease; when they are out of balance, they can cause it.

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

The tensiometer

The device used to measure blood pressure is called a tensiometer. Blood pressure readings are usually displayed in 3 numbers.

Here is an example:

Your blood pressure monitor shows the following figures: 130-80, 72. The first number is your systolic blood pressure, 130 mm Hg (millimetres of mercury). The number 80 refers to your diastolic blood pressure, which is 80 mmHg. The last number is your heart rate, 72 beats per minute.

How to measure your blood pressure at home

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

Most importantly, be sure to write down all results obtained from your blood pressure monitor during the week preceding your medical appointment.

Optimal conditions

Sit comfortably. Test your blood pressure after a 5-minute rest period; you have to wait a minimum of 30 minutes after physical activity.

You must wait 1 hour before you check your blood pressure after drinking coffee or any other drink containing caffeine (tea, soft drinks), or after eating any food that has a stimulant effect on the body, for instance, chocolate, etc.

You will have to wait 2 hours after a meal because the digestion process is a cardiovascular effort in itself and can distort your results and can distort your results.

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


Measurement must be taken twice a day.

Blood pressure measurement is to be made twice, first thing in the morning and a few minutes apart, before taking any medication, coffee or breakfast.

Blood pressure should be checked twice also before going to bed, a few minutes apart.

You must record each of the 2 measurements, even those that seem too high or too low or are not to your liking. If you choose to test your blood pressure a third time, you do not have to write down these results.

When the day is over, average these 4 values.

The weekly average is a true estimate.

The average of the last 6-day measurements before your medical appointment gives a reasonably accurate estimate of the real values of your blood pressure.