Science
★ In this disease the walls of the coronary arteries are gradually
damaged by deposits of fats and cholesterol (plaque). These are
laid down in the artery wall.
★ The wall becomes stiff which is why the term ‘hardening of the
arteries’ is sometimes used to describe this disease. The medical
term meaning ‘hardening of the arteries’ is atherosclerosis.
★ Although CHD is called a disease, it is probably a natural process
of ageing. However, it progresses more slowly in women and
some people develop it more than others.
A number of factors indicate the possible risk of early
development of CHD. The most important ones are:-
★ genetic factors
★ high blood cholesterol levels
★ aspects of a person’s life-style
★ The genetic factor is particularly
important. if a person has a father,
mother, brother or grandparents who
died early of CHD, there is a
possibility that the person will also
suffer CHD at an early age.
★ If a person has a very high cholesterol level in the blood,
that person can be at risk of CHD.
cholesterol in
an artery
Several life-style factors have be linked to CHD, including:-
★ a high fat diet – especially one rich in saturated fat from
animals,
★ lack of exercise,
★ smoking
★ leading a stressful life
Life-style factors linked to CHD
Lack of exercise Smoking
Diet rich in saturated fat Leading a stressful life
★ There are several possible consequences of the damage done to
coronary arteries in CHD. The most common effect is that at
some point an area of plaque can rupture (break open) inside
the artery. This causes a blood clot (thrombosis) to form on the
plaque’s surface.
If the clot becomes large enough it can mostly or completely
block blood flow through a
coronary artery.
★ The lack of oxygen will stop the
cardiac muscle cells contracting
properly and the portion of heart
muscle fed by the artery begins to
die. If the area of muscle affected
is big enough the regular beating
of the heart is interrupted and we
say that the person has suffered a
heart attack (myocardial
infarction
★ A less common cause of a heart attack is a severe spasm
(tightening) of a coronary artery. The spasm cuts off blood flow
through the artery. Spasms can occur in coronary arteries that
are not affected by atherosclerosis.
Movie 1.3 Heart function
and health
The role of diet in heart disease
★ Research has shown that our diet, especially the amount and
type of fat we eat, can increase the risk of coronary heart
disease.
★ Most foods contain different types of fat:- saturated,
polyunsaturated, monounsaturated and trans fats – and
some kinds are better for you than others.
★ Fat is essential in our diet. the important thing is to choose
the healthier types of fats and enjoy them in moderation.
Movie 1.4 What happens
during a heart attack?
★ Another consequence of the hardening of an artery is that the
artery is more likely to burst at the peak of pressure when a
pulse of blood is expelled from the heart.
★ Blood leaks out of the damaged vessel. The result of this is
most severe in the brain where an area of brain tissue can be
killed. This is a stroke.
Healthy fats
★ When choosing fats, the best options are unsaturated fats:-
monounsaturated and polyunsaturated fats.
These fats, if used in place of others, can lower your risk of
heart disease by:-
★ reducing the total cholesterol
★ reducing LDL ‘bad’ cholesterol in the body.
★ One type of polyunsaturated fat omega-3 fatty acids, may be
especially beneficial to your heart.
Omega-3s appear to:-
★ decrease the risk of coronary artery disease and may also
★ protect against irregular heartbeats
★ help lower blood pressure levels.
Below are the best sources of these healthy fats:-
★ Monounsaturated fat (MUFA) is found in olive oil,
peanut oil, avocados, nuts and seeds.
★ Polyunsaturated fat (PUFA) is found in vegetable oils
(such as corn and sunflower oils), nuts and seeds.
★ Omega-3 fatty acids are found in cold water fish
(such as salmon, mackerel and herring), tuna, flax
seeds, flax oil and walnuts.
Harmful fats
★ Saturated and trans fats (trans-fatty acids) are less healthy
kinds of fats. They can increase your risk of heart disease by:-
★ Increasing your total and LDL (‘bad’) cholesterol.
★ Dietary cholesterol isn’t technically a fat, but it is found in
food derived from animal sources. Intake of dietary cholesterol
increases blood cholesterol levels, but not as much as saturated
and trans fats do, and not to the same degree in all people.
Below are common food sources of harmful fats:-
★ Saturated fat is found in animal products such as fatty cuts
of meat, sausages, bacon and dairy products (butter, cheese
and cream).
★ Trans fats are found in commercially baked goods such as
biscuits, cakes and pastries and fried foods such as
doughnuts and chips.
Dietary cholesterol is found in animal products such as
fatty meats, liver and other organ meats, eggs, seafood
and dairy products (butter,
★ Cholesterol is a type of fat known as a sterol, and
is the main constituent of fatty deposits in blood
vessels.
★ It is deposited in the linings of the arteries when it is
oxidised (picks up oxygen circulating in the blood).
★ Antioxidants found naturally in
foods, especially:-
★ Vitamin E
★ Vitamin C
★ B-carotene
★ Selenium
★ help to stop cholesterol picking
up oxygen, so that it is less
readily deposited in the
coronary arteries and therefore
help to avoid coronary
heart disease.
cholesterol in
an artery
B-Carotene Selenium
Sources of natural anti-oxidants
Vitamin E, Vitamin C
B-Carotene, Selenium
Exercise has many beneficial effects on health:-
Exercise improves the efficiency of the heart
★ Regular exercise improves the strength of the heart muscle.
The heart of someone who exercises regularly is likely to be
able to pump more blood with each heart beat than the heart of
someone who does not take exercise.
★ The amount of blood pumped in one beat is called the stroke
volume.
★ An increased stroke
volume means that the
heart can pump enough
blood to the body with
fewer beats per minute, so
the resting pulse rate is
lower.
★ Overall, the heart does not
have to work so hard. Regular exercise can greatly decrease
the risk of suffering CHD.