B2.3 What factors increase the risk of heart disease?

B2.3 What factors increase the risk of heart disease?


The HEART is a muscular organ in the circulatory system. It beats automatically, pumping blood around the body to provide cells with oxygen and dissolved food for RESPIRATION. The blood removes carbon dioxide and water as waste products. The muscle cells in the heart need a constant supply of oxygen and nutrients, and for their waste products to be removed. So the heart requires its own blood supply in order to keep beating

Blood from the rest of the body enters the RIGHT ATRIUM of the heart. It then moves into the RIGHT VENTRICLE before being pumped to the lungs. When the oxygenated blood returns to the heart, it enters the LEFT ATRIUM. It then moves into the LEFT VENTRICLE before being pumped to the rest of the body.


The heart is a DOUBLE PUMP in the circulatory system because blood returns twice.

Arteries, Veins and Capillaries

CAPILLIRIES allow food and oxygen to diffuse to cells while waste is diffused from cells.

Narrow, thin-walled vessels – only one cell thick – that allow them to effectively perform their function

The heart rate can be measured by taking the pulse. If it is too fast or too slow, then it could indicate problems.

Another, more accurate way of checking how hard your heart is working is through measuring BLOOD PRESSURE. This records the pressure of the blood on the walls of the artery and it results from two forces:

  • SYSTOLIC pressure from the heart as it contracts and pumps blood into the arteries and through the circulatory system (HIGHER VALUE)
  • DIASTOLIC pressure from the force of the arteries as they resist the flow when the heart relaxes (LOWER VALUE)


High blood pressure is the biggest concern as it increases the risk of a heart attack- but low blood pressure can be dangerous too. However ‘NORMAL’ measurements for factors such as heart rate and blood pressure are always given as ranges because individuals vary.

Blood vessels called the CORONARY ARTERIES supply blood to the heart muscles. If they become blocked, a HEART ATTACK can happen

A heart attack can happen because:

  • Fatty deposits build up in the coronary arteries
  • A blood clot can form on a fatty deposit
  • The blood clot can block a coronary artery
  • Some heart muscle cells do not get the oxygen and nutrients the need
  • These cells start to die

HEART DISEASE is an abnormality of the heart that can lead to a HEART ATTACK. It is usually caused by LIFESTYLE and/or GENETIC FACTORS, not by infection. Lifestyle factors that can increase the risk of heart disease include:

  • Poor diet
  • Stress
  • Cigarette smoking
  • Misuse of drugs (e.g. Ecstasy, cannabis, nicotine and alcohol)

Reducing the risk when provided with lifestyle and genetic data:

  • Regular moderate exercise
  • Stop smoking
  • Reduce salt intake in diet
  • Monitor cholesterol levels (and use cholesterol-reducing drugs and foods if necessary
  • Maintain a healthy body weight

As heart disease is a big killer worldwide, studies continue to try to identify what factors cause it. These are called EPIDEMIOLOGICAL STUDIES and they try to identify whether a factor present in a large number of sufferers is the cause.  In addition, there are more genetic studies taking place to identify the genes responsible for heart disease.