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.
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
Blood Pressure cont.
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.
There are various factors that can increase blood pressure, including:
- being overweight
- drinking a lot of alcohol
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.
Fitness versus health
Fitness and health are not the same thing:
- fitness is the ability to do physical activity
- health is the amount of freedom from disease.
Fit people are able to carry out physical activities more effectively than unfit people. Their pulse rate is likely to return to normal more quickly after exercise.
Healthy people are free from disease and infection, but they may or may not be fit as well. It is possible to be fit but unhealthy, or healthy but unfit.
There are different ways to measure fitness. Factors include:
- stamina – endurance or staying power
- agility – how easily someone moves
- cardiovascular efficiency – how well a person's circulatory system works.
Cigarettes contain about 4,000 different chemicals, most of which are harmful to the body. These include:
- nicotine - the addictive substance in tobacco smoke
- carbon monoxide.
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.
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 after a sequence of events,
- 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 they need
- these cells start to die.
In the UK about 300,000 people have a heart attack every year.
The risk of developing heart disease is increased by several factors, including:
- high blood pressure
- high levels of salt in the diet
- high levels of saturated fat in the diet.
Heart disease cont.
High levels of salt in the diet can lead to increased blood pressure. High levels of saturated fats in the diet lead to a build of cholesterol in the arteries, causing a plaque and narrowing of the arteries.