Coming from the Greek words athero (meaning gruel or paste) and sclerosis (hardness), atherosclerosis involves deposits of fatty substances cholesterol, cellular waste products, and other substances in the artery's inner lining. Called "plague," this buildup usually affects both large and medium-sized arteries.

Atherosclerosis starts as early as childhood. A slow and complex disease, it often progresses as people age. In some people though the progress is more rapid and happens even in their twenty's.

Scientists believe this disease begins with damage to the innermost layer of the artery, called endothelium. Damage to this arterial wall are caused mainly by three things:

- Increased levels of cholesterol and triglycerides in the blood
- High blood pressure and
- Tobacco smoke

Research shows that males and those with a family history of premature cardiovascular disease have a greater risk of astherosclerosis. Unfortunately, these risk factors cannot be controlled. However, reducing the controllable risk factors for atherosclerosis prove to be beneficial. These controllable risk factors include:

- High bllod pressure
- Cigarette smoking / exposure to tobacco smoke
- High blood pressure
- Diabetes mellitus
- Obesity
- Physical inactivity

Tobacco smoke contributes to the worsening of atherosclerosis. It also speeds its growth in the coronary arteries, the aorta and arteries in the legs. Damage to the endothelium cause fats, cholesterol, platelets, cellular debris, calcium and other substances that bring about the further buildup of cells. These cells and the surrounding material then may increase in mass, enough to thicken the endothelium. This results in a shrink in the artery's diameter, decreasing blood flow and consequently reducing oxygen supply.

Blood pressure (strictly speaking: vascular pressure) refers to the force exerted by circulating blood on the walls of blood vessels, and constitutes one of the principal vital signs. The pressure of the circulating blood decreases as blood moves through arteries, arterioles, capillaries, and veins; the term blood pressure generally refers to arterial pressure, i.e., the pressure in the larger arteries, arteries being the blood vessels which take blood away from the heart. Arterial pressure is most commonly measured via a sphygmomanometer, which uses the height of a column of mercury to reflect the circulating pressure (see Non-invasive measurement). Although many modern vascular pressure devices no longer use mercury, vascular pressure values are still universally reported in millimetres of mercury (mmHg).

The systolic arterial pressure is defined as the peak pressure in the arteries, which occurs near the beginning of the cardiac cycle; the diastolic arterial pressure is the lowest pressure (at the resting phase of the cardiac cycle). The average pressure throughout the cardiac cycle is reported as mean arterial pressure; the pulse pressure reflects the difference between the maximum and minimum pressures measured.

Typical values for a resting, healthy adult human are approximately 120 mmHg (16 kPa) systolic and 80 mmHg (11 kPa) diastolic (written as 120/80 mmHg, and spoken as "one twenty over eighty") with large individual variations. These measures of arterial pressure are not static, but undergo natural variations from one heartbeat to another and throughout the day (in a circadian rhythm); they also change in response to stress, nutritional factors, drugs, or disease. Hypertension refers to arterial pressure being abnormally high, as opposed to hypotension, when it is abnormally low. Along with body temperature, blood pressure measurements are the most commonly measured physiological parameters.