8.4 Cardiovascular diseases
Cardiovascular diseases affect the heart or blood vessels (arteries, veins and capillaries).
Cardiovascular diseases are the biggest cause of deaths worldwide and the incidence of
these diseases is rising rapidly in countries like South Africa. Cardiovascular diseases can be
avoided through improvements in eating habits and through regular exercise. In this section
we will study the causes of heart attacks and strokes as well as how these may be treated.
We will also study the causes of high and low blood pressure and how these have an effect
on our well-being. We will finally discuss the types of treatments that are available such as
stents, valve replacements, bypass surgery, pacemakers and heart transplants.
See video: SHORTCODEat http://www.everythingscience.co.zaSee video: SHORTCODEat http://www.everythingscience.co.zaSee video: SHORTCODEat http://www.everythingscience.co.zaHeart attack
This is also referred to as amyocardial infarction. Heart muscles are provided with oxy-
genated blood by a system of coronary arteries. Blocked flow of blood can cause the death
of cardiac muscle due to lack of oxygen. Arteries get blocked as a result of the gradual build-
up of lipids and cholesterol, which form aplaque. This condition of plaque build up in the
arteries is referred to asatherosclerosis. When a plaque bursts, it causes blood to clot at the
site of the rupture and obstructs the artery (see diagram in Figure??). Often there are no
symptoms of atherosclerosis. However, some people who have narrowed coronary arteries
experience chest pain, (angina), when blood flow to the heart is insufficient.
Chapter 8. Transport systems in animals 243