Atherosclerosis or the "hardening of the arteries" is the disease of the arteries.
It includes coronary heart disease that affects mainly medium to large arteries.
There is wide range of risk factors for atherosclerosis leading to chronic inflammation within the walls of the arteries.
The build up of "atheroma" or plaque within the arterial walls are the hall mark of atherosclerosis.
This process of the building up of the atheroma is a process called "atherogenesis".
This process if mainly due to the infiltration of monocytes (white blood cells) in the outer most layer of the arterial wall due to a damage.
Although this phenomenon is not fully understood, it is thought that it is a protective mechanism to engulf access cholesterol.
As these monocytes enter the arterial wall it is converted to macrophages (bacteria engulfing cells), a process called "differentiation".
This is the start the slow process of atherogenesis.
As monocyte differentiates it expresses receptors on its cell surface called "scavenger receptors".
They are responsible for attacking bacteria and destroying it.
In this cause the receptors are very much "friendly" for cholesterol or more specifically "low density lipoprotein or LDL).
This LDL present in the plasma (the blood flow) can sometimes be modified specially by the free radicals in cigarette smoke making it more easily identifiable to the receptors.
Once the receptors engulf cholesterol they can accumulate within the macrophages, it then forms something called a "foam cell".
When subsequently large numbers of macrophages have accumulated cholesterol it is called a cholesterol filled "plaque" referred by doctors.
This plaque will progress and form a more complicated plaque and form a lesion leading to a blockade of the blood flow.
This eventually if unchecked will lead to clinical complications due to the rupture of the lesion.
The most common clinical complications of atherosclerosis include heart attacks and stroke due to restricted blood flow to the heart and brain respectively.