Biology » Introducing Animal Systems » Cardiovascular Diseases

Heart Attack

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.

Heart Attack

This is also referred to as a myocardial infarction. Heart muscles are provided with oxygenated 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 a plaque. This condition of plaque build up in the arteries is referred to as atherosclerosis. When a plaque bursts, it causes blood to clot at the site of the rupture and obstructs the artery. 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.

Heart Attack

1. Normal arteries have a wide diameter through which blood can easily flow. 2. Plaque forms on the walls of the artery, narrowing the lumen. 3. When the plaques bursts, platelets form a blood clot at the site of rupture, which can obstruct the artery.

Heart Attack

Heart attack: the blood clot blocks the coronary arteries and cardiac muscle dies from lack of oxygen.

Optional Video: Heart Disease and Heart Attacks

Understanding coronary artery disease and myocardial infarctions by Khan Academy. Left-most image from wikipedia user ZooFari (other two images in public domain). Video is licensed under CC-BY-SA.

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