Atherosclerosis Flashcards
what is the innermost later of an artery called and what does it consist of?
Tunica Intima, consists of the endothelium, subendothelial layer and elastic membrane
what is the inner lining of the tunica called and what is it?
It is called the endothelium
it is a continuous thromboresistant layer between the blood and potentially thrombogenic subendothelial tissue
what is the function of the endothelium of an artery
Modulates tone, growth, hemostasis and inflammation throughout circulatory system
what is the middle layer of an artery called and what does it consist of?
- Tunica Media
- Consists of smooth muscle cells and an elastic membrane
what is the outer layer of an artery called and what does it consist of?
- tunica externa / tunica adventitia
- Composed of extracellular matrix with fibroblasts, mast cells and nerve terminals
what are the functions of the tunica intimia, media and externa
- Tunica intima creates the pathway for oxygenated blood to be carried to the site of perfusion
- Tunica media is comprised of smooth muscle that dilates and constricts in response to cardiac output needs
- Tunica externa / adventitia connects arteries to other structures in the body
what is the word break down of atherosclerosis
- athero = porridge, soft, fatty, gruel-like (refers to soft lipid-rich material in the center of atheroma)
- sclerosis = hard, scarring. (refers to connective tissue in the plaques)
what is atherosclerosis
- A pathologic process that causes disease of the coronary, cerebral, and peripheral arteries
how does atherosclerosis begin
with the development of “fatty streaks” within arterial walls.
can develop as early as childhood!!!
what are the 6 histological steps of atherosclerosis
- Fatty streak formation
- Fibrous cap development
- Disruption of the vasa vasorum
- Proliferation of the fibrous plaque
- Development of an advanced lesion
- Intraplaque hemorrhage
histological development of atherosclerotic plaque can help us understand the adverse events that occur in CHF
what causes the formation of fatty streaks in atherosclerosis
- focal thickening of the intima d/t accumulation of foam cells and extracellular matrix.
- Lipids accumulate, creating the fatty streak
- fatty streaks may also contain T lymphocytes
what is biglycan?
a specific protein created by the coronary arteries that can trap VLDL and LDL
what are foam cells
lipid laden macrophages
( in notes, slide 14)
describe the process of fatty streak formation
- Vascular injury precipitates monocyte binding to endothelium
- Monocytes cross endothelium and become activated tissue macrophages
- Macrophages “eat” oxidized LDL, becoming foam cells
- T cells release cytokines, which further activates macrophages and cause smooth muscle cells to proliferate
- Smooth muscle cells move to subendothelial space, producing collagen and taking up LDL, adding to foam cell accumulation
what is a fibrous cap
- A dense, collagen-based layer of connective tissue that covers the well-defined lipid core of an atherosclerotic plaque
- this provides further stability to the atherosclerotic plaque
what is the vasa vasorum and what does it do?
- A network of micro-vessels originating from tunica adventitia of large arteries
- Serve to provide oxygen and nutrients to outer layers of arterial wall
how is the vasa vasorum disrupted with atherosclerotic plaque?
- as plaque expands, it creates its own thin-walled microvasculature. this increases the risk of microvascular hemorrhage, leading to progression of atherosclerosis
What causes the development of fibrous plaque? what is this plaque made of
the accumulation of connective tissue.
this plaque is made up of lipid-containing smooth muscle cells and an extracellular lipid pool
what characterizes advanced lesions
Characterized by a necrotic lipid–rich core and calcified regions that develop over time
what is the difference between positive and negative remodeling of coronary arteries in response to atheroma formation