Biology B1 - Fitness and Health

Blood pressure

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.
• 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.

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
• 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.

Measuring fitness

There are different ways to measure fitness. Factors include:

• strength
• stamina – endurance or staying power
• flexibility
• agility – how easily someone moves
• speed
• cardiovascular efficiency – how well a person's circulatory system works.

Smoking

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 and blood pressure

Smoking increases blood pressure by raising the heart rate.

Nicotine increases the heart rate

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.

Heart disease

Blood vessels called the coronary arteries supply blood to the heart muscles. If they become blocked, a heart attack can happen.

Heart attacks

A heart attack can happen after a sequence of events,

• fatty deposits build up in the coronary arteries
• a blood clot can form ona 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.

Factors for heart disease

The risk of developing heart disease is increased by several factors, including:

• smoking
• high blood pressure
• high levels of salt in the diet
• high levels of saturated fat in the diet.

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.

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

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

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