Atheroma & Thrombi: Causes & Effects

[Cheman]

Atheroma and thrombi...

I have read that atheromas usually result when a tear occurs in the endothelium occurs which allows phagocytes and LDL's to enter, etc.
Why does this occur rather than a thrombus form first? Afterall, clots form when we cut ourselves as a result of the blood being exposed to collegen - surely this would be exposed when a tear occurs in the endothelium?

Also, I have read that atheromas, as they are rigid, can break and this leads to formation of thrombi - is this because collegen in vessal walls is exposed, or something inside the atheroma?

Thanks in advance.

 

[Monique]

I have read that atheromas usually result when a tear occurs in the endothelium occurs which allows phagocytes and LDL's to enter, etc.

Actually the LDL accumulates underneath the endothelium without there being a tear. Also, macrophages can enter the endothelium by squeezing themselves so there is no tear.

So, what happens is that LDL accumulates, macrophages are attracted that try to eat the LDL, the macrophages overeat and die, more macrophages get attracted due to an inflammation response, endothelial cells start to replicate, this thickening of endothelium leads to a narrowing of the bloodvessel. The narrowing of the bloodvessel can be dangerous when it leads to an obstruction, but it is more dangerous to have an unstable plaque which can tear. You are correct that this leads to thrombi formation, because a chemical that is called TF (tissue factor) is released from the inner part of the vessel wall that activates coagulation.

 

[ravenprp]

Atheroma and thrombi are both types of vascular lesions that can have serious consequences on our health. Atheromas are fatty deposits that accumulate in the inner lining of our blood vessels, known as the endothelium. These deposits can cause the arteries to become narrowed and hardened, leading to reduced blood flow and increased risk of heart attack and stroke. On the other hand, thrombi are blood clots that can form in response to an injury or damage to the blood vessel wall.

To answer your first question, atheromas occur when there is damage to the endothelium, which allows for the entry of phagocytes and LDL cholesterol. This process is known as the "response-to-injury" hypothesis. When the endothelium is damaged, it triggers an inflammatory response, causing immune cells to enter the vessel wall and form a fatty plaque. This process is different from the formation of a thrombus, which occurs in response to an injury or damage to the blood vessel itself.

As for your second question, atheromas can indeed rupture and lead to the formation of a thrombus. This is because the rupture exposes the underlying collagen fibers in the vessel wall, which can trigger the formation of a blood clot. Additionally, the fatty deposits in the atheroma can also release substances that promote blood clotting, further increasing the risk of thrombus formation.

In summary, atheromas and thrombi are both serious conditions that can have different causes and effects. While atheromas result from damage to the endothelium, thrombi form in response to an injury or damage to the blood vessel wall. However, both can lead to serious health complications if not properly managed. It is important to maintain a healthy lifestyle and manage any underlying health conditions to prevent the development of these vascular lesions.