Blood Pressure

Blood pressure

This is the amount of pressure exerted on the arterial walls by blood when the left ventricle contracts. There are two measurements:

Systolic – This is the maximum pressure of the heartbeat. This happens during active ventricular contraction, when the heart muscle contracts and pushes the blood out into the body through the arteries.

Diastolic – This is the minimum pressure of the heartbeat. This happens during a rest or pause between contractions when the heart muscle relaxes and blood flows into the heart from the veins.

Blood pressure is measured by an instrument called a sphygmomanometer. It is measured in millimetres of mercury and is expressed in reading of systolic over diastolic, eg 120/80mm Hg.

Factors that affect blood pressure

• Anger
• Stress
• Pain
• Fright
• Excitement
• Exercise
• Smoking
• Drugs
• Body weight

Pulse

This is felt in arteries and corresponds to the beating of the heart. The beat of the left ventricle is very strong and can be felt a long way from the heart. The pulse is felt in any artery that lies close to the surface. Common locations are the wrist and neck.