Atherosclerosis Flashcards
(33 cards)
Atherosclerosis
a disease of the arteries characterized by the deposition of fatty material on their inner walls.
What stage are the inner vessel walls at during the first decade of atherosclerosis
Foam cells > fatty streak
What stage are the inner vessel wall at during the third decade of atherosclerosis
Intermediate lesion > atheroma
What stage are the inner vessel walls at during the fourth decade of atherosclerosis
Fibrous plaque > complicated lesion/rupture
(Smooth muscle collagen. Thrombosis hematoma)
What stage of atherosclerosis is clinically silent
Fatty streak
What stage of atherosclerosis causes temporary symptoms
Fibrous plaque
What stage of atherosclerosis causes permanent damage
Plaque rupture/thrombosis
What vessels are susceptible to atheroma formation
Despite systemic nature of many risk factors, arterial areas subject to either disturbed flow or low shear stress have particular susceptibility to atheroma formation
Three layers of arterial wall
Tunica externa (collagen), tunica media (smooth muscle), tunica intima (endothelium + ECM)
The tunica media is separated off by ex/internal elastic membrane
What are the components of the fibrous cap
Smooth muscle cells, macrophages, foam cells, lymphocytes, collagen, elastin, proteoglycans, neovascularization.
Components of the necrotic centre
Cell debris, cholesterol crystals, foam cells, calcium
How does thrombosis occur
Rupture of fibrous cap allows contact between blood and thrombogenic lipid core platelet aggregation and thrombus formation occludes arterial lumen
What are lipoproteins
Particles made of proteins and fats that transport cholesterol and other lipids through blood cells.
What are foam cells
Macrophages that localise to fatty deposits and ingest low density lipoproteins and become loaded with lipids.
Role of nitric oxide in endothelial cells
Small, soluble gas with vasodilatory, anti-inflammatory, and antioxidant properties that play a role in the maintenance of vascular homeostasis
What causes rupture of fibrous cap
The combination of increased mechanical stress on the fibrous cap and weakening of the fibrous cap extracellular matrix leads to plaque rupture.
What causes rupture of fibrous cap
The combination of increased mechanical stress on the fibrous cap and weakening of the fibrous cap extracellular matrix leads to plaque rupture.
In what form do lipids circulate
Free cholesterol, cholesterol ester, triglycerides, and phospholipids
What is the precursor of steroid hormones and bile acids
Lipids
Describe the mechanism of endocytosis of lipoproteins
Lipoprotein binds to lipoprotein receptor and enters forming Claritin coated pit.
Receptor detaches and is recycled to membrane.
Endosome becomes lysosome
Explain the mechanism of transcytosis of lipoprotein
Recognition of LDL at caveolae which is rich in scavenger receptors, SR-B1 and ALK1 which activate the rac system which allows for the formation of an endosome that can travel from the apical to the base side of the endothelial cell.
What is LOX-1
An oxLDL (scavenger) receptor
Epithelial cell: apoptosis, oxLDL uptake, endothelial injury, monocyte adhesion, senescence
What is the difference between athero-prone and athero-protected endothelial membranes
In athero-prone regions, the distal flow increases the formation of caveolae and increases the contact of LDL with caveolae
Laminar flow decreases the contact of LDL with caveolae
How are macrophages foam cells formed
Uptake of oxLDL by macrophages
Once inside, oxLDL is broken down and free cholesterol and fatty acids are released, the macrophages accumulate these lipids forming lipid droplets.
