Blood Pressure

Blood is under pressure in the arteries so that it reaches all parts of the body. Diet, exercise and other factors can affect the risk of heart disease developing.

Arteries carry blood away from the heart. Blood in the arteries is under pressure because of the contractions of the heart muscles. This allows the blood to reach all parts of the body.

Measuring Blood Pressure

Blood pressure is measured in millimetres of mercury, mmHg. There are two measurements:

• systolic pressure - the higher measurement when the heart beats, pushing blood through the arteries, and
• diastolic pressure - the lower measurement when the heart rests between beats

A young, fit person should have a blood pressure of about 120 over 70, which means their systolic pressure is 120 mmHg and their diastolic pressure 70 mmHg.

High and Low Blood Pressure

There are various factors that can increase blood pressure, including:

• smoking
• being overweight
• drinking a lot of alcohol
• stress

Example: Smoking and the effect on blood pressure - Smoking increases blood pressure by raising the heart rate. Nicotine itself increases the heart rate and carbon monoxide reduces the oxygen-carrying capacity of the blood. It combines with haemoglobin in red blood cells, preventing oxygen combining with the haemoglobin. This causes an increase in heart rate to compensate for the reduced amount of oxygen carried in the blood.

A balanced diet and regular exercise can reduce high blood pressure.

Extremes of blood pressure can create problems. High blood pressure can cause:

• kidney damage
• burst blood vessels
• damage to the brain, including strokes.

Low blood pressure can cause dizziness, fainting and poor blood circulation.