Blood pressure is a measure of the outward force exerted by the blood on the arteries in your body. A healthy body has a blood pressure that is just enough to push the blood into all of the smaller blood vessels of your body, called capillaries.

Blood pressure is created by a combination of factors in your body:

1. Force of the heart pushing blood out of the heart chambers into the aorta.
2. The volume of blood you have circulating in your circulatory system.
3. The size of the blood vessels that the blood has to travel through. As the diameter of the blood vessels decrease, it requires greater pressure to push blood through.

Your body has various systems in place to keep your blood pressure within very strict limits. Negative feedback systems are in operation. Sensors in your carotid artery and wall of the aorta monitor blood pressure, and if it gets too high, a signal is sent to the medulla in your brain, which in turn reduces your heart rate, and increases vasodilation (opening up) in blood vessels (called arterioles). This means the same volume of blood is distributed between more blood vessels, so overall blood pressure drops. When blood pressure drops, the opposite happens. Heart rate increases, and vasoconstriction (closing off) occurs in arterioles.

Things can and do go wrong

Various factors can cause high blood pressure (which is called hypertension by the medical community).

There are varying opinions on what measurements actually constitute high blood pressure, but the majority of source agree that:

Greater than 140 mmHg Systolic Pressure, and greater than 90 mmHg diastolic pressure is high. If you have two or more readings taken on different occasions, you may be diagnosed as having hypertension.

Symptoms & Signs of High Blood Pressure

Unfortunately high blood pressure has very few (if any) symptoms, and is often called the “Silent Killer”. You should go to your doctor and get your blood pressure checked frequently. Alternatively you could buy a personal digital blood pressure monitor and make the measurements at home. It could save your life.

What Causes of Hypertension

In most cases, the cause of hypertension is unknown. However, there are some factors which can contribute to it.

• Excessive alcohol
• Tobacco
• Obesity
• Salt in the diet
• genetic factors

Blood pressure can also increase in pregnancy, when the patient has kidney problems, or hormonal problems like an over-active thyroid, and even sleep apnea (a condition which causes the sufferer to stop breathing for a short time when asleep).

There are also some medications that can cause increased blood pressure including antacids, oral contraceptives, decongestants and diet pills. Please read the notes that come with any medication you are taking for details on possible blood pressure side-effects.

Risks of Hypertension

If your blood pressure is too high, your heart and arteries are put under stress, and can hate fatal consequences.

• Hypertension causes damage to the walls of your arteries causing them to become less elastic. This hardening of the arteries makes it much easier for harmful cholesterol to stick to your artery wall, reducing the diameter of the blood vessel through which blood must flow. With narrowing of the arteries, your heart must work much harder to push the blood through, and blood pressure rises. Possible consequences include heart attack, stroke, kidney failure, or even the amputation of the leg.
• Risks of heart attack and stroke are greatly increased in patients with high blood pressure.
• Heart enlarges which can cause heart attack.
• Bulging of the arteries outwards. These aneurysms can rupture, leading to blood spilling out into surrounding tissues. If this occurs in the brain, the patient will likely suffer a stroke.
• Blood vessels in the kidneys narrow possibly leading to renal failure.
• Blood vessels in the eyes can burst, causing a deterioration in sight, even blindness.

Treatment of high blood pressure

See our high blood pressure diet page to read about how you can reduce your blood pressure naturally. Also you can read about some of the medications used to treat high blood pressure, and possible side-effects of these drugs.

Glossary of terms related to hypertension / high blood pressure.

Arterial Hypertension – also just called “hypertension”, refers to a condition where blood pressure is elevated above normal. Normal is usually quoted as below 120/80.

White coat syndrome – a condition where an individual has elevated blood pressure at the doctors office, yet has much reduced / normal blood pressure at home.

Hypertensive emergency – a severe hypertension that impairs proper functioning of the body’s organs. Requires medical treatment to aggressively lower blood pressure.

Exercise hypertension – is a rise in blood pressure in response to exercise. This does not affect everybody, and in healthy individuals, we would expect to see a small drop in blood pressure during exercise due to improved blood flow.

Malignant hypertension – chronic high blood pressure (> 240/120) resulting in organ damage, especially the eyes, kidneys, brain and lungs. Malignant hypertension is accompanied by swelling of the optic disk.

Pulmonary hypertension – is an increase in blood pressure in the pulmonary artery (carrying blood from the heart to the lungs) or vessels in the lungs. The right side of the heart is put under pressure, and one of the common symptoms is shortness of breath and chest pains during exercise.

Renovascular hypertension – also called “renal hypertension” refers to the kidneys. This is caused by a narrowing of the renal arteries (carrying blood to the kidneys), reducing blood flow to the kidneys, which respond by sending out signals to the body to raise blood pressure. Renal hypertension is a secondary form of hypertension (which just means that we know why it happens).

Systolic pressure – the peak pressure in your circulatory system when the heart contracts. When the heart beats, blood is forced out into the aorta, increasing the pressure.

Diastolic pressure – The lowest pressure in your circulatory system, which occurs during the resting stage of the cardiac cycle (heart is resting between beats).

The pressure of your blood depends on a number of factors including:

• the force created by your heart pumping blood into your arteries
• the volume of your blood
• the resistance your blood encounters as it moves through your blood vessels.

You body needs to make sure that there is sufficient pressure to push the blood into all of the capillaries around your body. Capillaries are the smallest blood vessels in your body, and ensure that all cells in your body receive nutrients they require to live.

Maintaining normal blood pressure is delicately balanced. Too high, and your heart and blood vessels are put under strain. Too low and the low blood pressure means some cells may not get the nutrients they require.

High blood pressure is often called the “Silent Killer” since there are often no symptoms. For this reason, it is important you get your blood pressure checked regularly.

Blood pressure readings can be taken by your doctor using a sphygmomanometer and stethoscope, or at home using a blood pressure monitor (the easiest ones to use are digital monitors). The home monitors generally come in two forms. One places a cuff around your wrist, while the other places a cuff around your upper arm (level with your heart). I personally have tried both types and found the most accurate one to be the upper arm cuff.

The blood pressure “numbers”

The blood pressure reading is two numbers. These are the two pressures of your blood at varying stages of your heart beat cycle:

The larger number is the systolic pressure, the lower number is the diastolic pressure.

Systolic pressure is the blood pressure being pumped into the aorta when the heart beats.

Diastolic pressure is the blood pressure in the arteries when the heart relaxes between beats.

Blood pressure does vary with age, sex and health, but in general, a healthy blood pressure is 120/80, or 120 over 80.

This means that systolic blood pressure is 120 mmHg, and the diastolic blood pressure is 80 mmHg.

Your blood pressure can actually tell a doctor a lot about the health of your heart and blood vessels. High blood pressure means that your heart is having to work harder to push your blood to all the cells in your body.

This can happen if e.g. you have narrowing of the arteries, since this narrowing increases the resistance of your blood vessels, and requires more pressure to get the blood through.

High blood pressure is also called hypertension, and can have serious consequences if not treated. e.g. high blood pressure can weaken the artery walls, and lead to rupture. If this happens in the brain, it can lead to a stroke.

There are a wide range of medicines and medications available to treat high blood pressure, and some alternative therapies such as acupuncture may also help, but you can also take immediate steps by looking at your diet and increasing your daily exercise (walking is a great exercise).

We explore some of the dietary considerations on this site, but please do consult a doctor before changing your diet or undertaking an exercise program.