The Process of Atherosclerosis

Introduction

Atherosclerosis is a complex and progressive medical condition that affects the arteries of the circulatory system. It is the primary underlying cause of several cardiovascular diseases (CVD), including angina, heart attack, stroke, and peripheral vascular disease. In this topic, we will delve into the process of atherosclerosis, its effects on arteries, and how it contributes to changes in blood pressure.

The Process of Atherosclerosis

Atherosclerosis is characterised by the gradual accumulation of fatty materials, primarily cholesterol, along with fibrous tissue and calcium deposits within the walls of arteries. This buildup forms a lesion known as an atheroma or plaque. The process of atherosclerosis unfolds as follows:

1. Initial Injury

The endothelium, which is the inner lining of the artery, becomes injured due to various factors, such as high blood pressure, smoking, and inflammation.

2. Formation of Fatty Streaks

In response to the injury, low-density lipoproteins (LDL), commonly referred to as "bad cholesterol," begin to accumulate in the arterial wall. These LDL particles are prone to oxidation and are taken up by immune cells called macrophages, forming fatty streaks within the artery.

3. Atheroma Development

Over time, the fatty streaks develop into more complex lesions known as atheromas or plaques. These plaques consist of a core of cholesterol, surrounded by fibrous tissue and calcium deposits.

4. Arterial Changes

As the atheromas grow, they lead to structural changes in the artery. The artery loses its elasticity, becoming stiff and less able to respond to changes in blood pressure. Additionally, the diameter of the arterial lumen (the inner opening of the artery) becomes narrowed due to the presence of the plaque.

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The Process of Atherosclerosis

Effects on Arteries

Atherosclerosis has profound effects on the arteries:

Reduced Blood Flow

The accumulation of plaques narrows the arterial lumen, restricting the flow of blood. This reduction in blood flow can have significant consequences depending on the location of the affected artery.

Loss of Elasticity

The arterial walls lose their elasticity, making them less responsive to changes in blood pressure. This can result in increased blood pressure (hypertension), which places additional stress on the heart and the entire circulatory system.

Contribution to Blood Pressure Changes

Atherosclerosis directly contributes to changes in blood pressure through several mechanisms:

Stiffening of Arteries

The loss of arterial elasticity makes the arteries less compliant. As a result, they cannot expand and contract efficiently in response to changes in blood flow and pressure.

Narrowing of Arterial Lumen

The presence of plaques narrows the arterial lumen, which further impedes the smooth flow of blood. This narrowing increases the resistance to blood flow and elevates blood pressure.