With advancing age, cholesterol and calcium are deposited gradually in the walls of the coronary arteries. These deposits are called plaques. The process is known as atherosclerosis, or "hardening of the arteries."
A diet high in cholesterol combined with smoking and lack of exercise can accelerate this process.
As these plaques grow, they begin to impede the flow of blood.
The growing plaque is like a firm shell with a soft inner core containing cholesterol.
As blood hits a plaque during each heartbeat, the plaque may crack open and expose the inner cholesterol.
The cholesterol may cause a blood clot to begin to form.
The plaque and the blood clot block the artery partially or completely. The more the artery is blocked, the greater the resulting damage to the heart.
Atherosclerotic coronary artery disease
This most common type of heart disease is associated with several risk factors. The greater the number of risk factors you have, the more likely you are to have atherosclerosis. The most common risk factors are as follows:
Hereditary (runs in the family)
High cholesterol in blood, especially high levels of "bad cholesterol" (LDL, low-density lipoprotein) and low levels of "good cholesterol" (HDL, high-density lipoprotein)
Cigarette smoking or other tobacco use, including cigars and chewing tobacco
Obesity or excess weight
High blood pressure (hypertension)
Diabetes
Physical inactivity, lack of regular exercise (sedentary lifestyle)
Coronary arteries can be blocked by conditions other than atherosclerosis. These include inflammatory diseases of the arteries, trauma such as a cut or stab wound to the heart, and diseases that cause thickening of the coronary arteries.
Coronary embolization may cause a heart attack. Coronary embolization refers to a clot from elsewhere in the body breaking off and traveling to the heart.
Other causes of heart attack are blood or oxygen supply problems or outside influences such as cocaine abuse and complications from bypass or catheterization.
Certain heart problems leading to heart attack may be present from birth.
Circulatory System
Circulatory System, or cardiovascular system, in humans, the combined function of the heart, blood, and blood vessels to transport oxygen and nutrients to organs and tissues throughout the body and carry away waste products. Among its vital functions, the circulatory system increases the flow of blood to meet increased energy demands during exercise and regulates body temperature.
