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Disease process
'''Atherosclerosis''' is a disease process in which cholesterol accumulates in the walls of an artery. It is a chronic process, that gradually leads to stenosis, or narrowing, of the artery. The rupture of an atherosclerotic plaque can lead to the formation of a thrombus, which can occlude an artery, preventing the flow of blood. Depending on the location of the artery, this can lead to a variety of medical presentations.
'''Atherosclerosis''' is a disease process in which [[cholesterol]] accumulates in the walls of an artery. It is a chronic process, that gradually leads to stenosis, or narrowing, of the artery. The rupture of an atherosclerotic plaque can lead to the formation of a thrombus, which can occlude an artery, preventing the flow of blood. Depending on the location of the artery, this can lead to a variety of medical presentations.
==Epidemiology==
==Epidemiology==
Atherosclerosis generally does not affect individuals below the age of 35. While cholesterol may be transiently deposited, it is quickly removed. Above the age of 35, reports of prevalence are highly variable. Some studies report ranges of between 2.5% and 31.7% in asymptomatic individuals<ref>[http://eurheartj.oxfordjournals.org/content/21/1/13.full.pdf Prevalence of coronary atherosclerosis in asymptomatic population]. ''European Heart Journal, 21, 13-14''</ref>.
Atherosclerosis generally does not affect individuals below the age of 35. While cholesterol may be transiently deposited, it is quickly removed. Above the age of 35, reports of prevalence are highly variable. Some studies report ranges of between 2.5% and 31.7% in asymptomatic individuals<ref>[http://eurheartj.oxfordjournals.org/content/21/1/13.full.pdf Prevalence of coronary atherosclerosis in asymptomatic population]. ''European Heart Journal, 21, 13-14''</ref>.
==Disease Process==
Cholesterol circulates in the bloodstream contained in molecules called lipoproteins. The two most common forms are high-density lipoproteins ("good cholesterol", which reduces atherosclerosis) and low-density lipoproteins ("bad cholesterol", which increases atherosclerosis).
The wall of an artery is made of up three layers - the innermost ''tunica intima'', the muscular ''tunica media'', and the outer ''tunica adventitia''. Atherosclerosis affects the middle of these layers. It is initiated by injury to the wall of an artery. In most cases, this is due to [[hypertension|high blood pressure]]. This increases the permeability of the tunica intima, allowing the passage of lipoproteins and white blood cells called [[macrophage|macrophages]] into the tunica media. Macrophages are responsible for engulfing debris through the process of phagocytosis, which allows its removal from the body. When they phagocytose lipoproteins, they trap the cholesterol in the tunica media, and become ''foam cells''.
==References==
==References==
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