Blood pressure is the pressure inside the arteries. This pressure is exerted by the blood on
the artery walls, and is expressed in millimetres of mercury (mmHg).
When the heart contracts (systolic or maximum pressure): the pressure suddenly increases
in the arteries, this is the first number that your physician gives you when measuring your
blood pressure. It is normally under 15 (150 mmHg).
When the heart relaxes between beats, the pressure decreases (diastolic or minimum pres-
sure): This pressure corresponds to the second number your physician gives you when
measuring your blood pressure. It is generally between 5 and 9 (50 and 90 mmHg).
Both numbers provide important information about your health. The harder it is for the
blood to flow through the arteries, the higher these two numbers will be. If the blood pres-
sure is persistently above normal, this is called hypertension.
Blood pressure varies considerably throughout the day, and these variations are even more
significant in hypertensive subjects. It is lower in the morning and increases in the afternoon
and the evening. When sleeping, it decreases. Blood pressure is lower in summer than in win-
ter, and it rises noticeably with age. Blood pressure also increases during exercise, sex, preg-
nancy, stress, etc.
EXAMPLE OF THE BLOOD PRESSURE VARIATION IN A 35 YEAR OLD MALE
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Factors that may cause blood pressure changes: breathing, exercise, stress, anxiety, changes
in temperature and/or environment, meals, arguments, bathing, smoking, drinking alcohol...
Note : One or two blood pressure readings will not provide a true indication of your blood pressure, it is
important to measure it daily and regularly in order to obtain accurate data. Sharing your results with
your physician, may help him/her diagnose you and prevent potential health problems.
The World Health Organization (WHO) developed the blood pressure typology shown in
the table below (1999 - revised in 2003). Nevertheless, this typology is just a general guide,
as blood pressure varies from one person to another, based on age, weight, and health.
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