atherosclerosis

Question 1

what is atherosclerosis?

Answer 1

appearance of soft material and its deposition—> resulting in stiffening vessels
LESION formation in INTIMA of larger arteries

Question 2

layers of a vessel?

Answer 2

tunica externa= OUTERMOST layer, collagen and elastic
tunica media= middle layer, SM and elastic (vasoconstricts and dilates)
tunica intima= INNERMOST, simple squamous, reduce friction

Question 3

where does atherosclerosis occur?

Answer 3

in arteries in INTIMA of vessel—>

lesion STRETCHES vessel wall and slowly CLOSES off LUMEN

Question 4

process of atherosclerosis?

Answer 4

50% patency of lumen, compromised perfusion—> ISCHEMIA—> infarction (necrosis from ischemi)
ischemic pain!

Question 5

what is the lesion known as?

Answer 5

atheroma (deposited in vessel wall not lumen!)

-made of fat and fibrous tissue “fibro-fatty lesion”

Question 6

the tissue _____ to the occlusion suffers damage?

Answer 6

distal to the occlusion—> PVD, MI, Stroke

Question 7

what are the 3 stages of a lesion?

Answer 7

1. fatty streak
2. calcification
3. complicated lesion

Question 8

what is the fatty streak stage

Answer 8

discolouration of wall in vessel (yellow streak)

• macrophages, lipids, foam cells
• pt asymptomatic

Question 9

what is the calcification stage?

Answer 9

-accumulation of calcium crystals from necrotic cells
-scar tissue forms on vessels
“clinical lesion” presents with manifestations

Question 10

what is the complicated lesion?

Answer 10

hemorrhaging into plaque (bleeding into lesion), develops into a thrombus (blood clot)

Question 11

pathogenesis of atherosclerosis? (4 things)

Answer 11

1. endothelial cell injury
2. migration of inflammatory cells
3. lipid accumulation and smooth muscle cell proliferation
4. plaque structure

Question 12

endothelial cell injury…

Answer 12

-late 20s, early 30s subtle changes begin in endothelial lining in vessels (vasc epithelial w single layer of cells that protect)
risk factors: smoking, increased levels of LDL, immune mechanisms and mechanical stress associated with HTN
CRP levels increase, serum marker of inflammation but increased CRP with no inflammation may also indicate atherosclerosis

Question 13

migration of inflammatory cells?

Answer 13

monocytes and other inflammatory cells adhere to epithelium and migrate from endothelial cells to intima
—> transform into macrophages

Question 14

lipid accumulation and smooth muscle proliferation?

Answer 14

activated macrophages release toxic oxygen species that oxidize lipids (mostly LDL) forming free radicals that damage the wall of vessels, attracts platelets

• —> clot inside lumen forms
• –> macrophages engulf oxidized lipids to become foam cells; this is protective because it removes excess lipids from circulation BUT leads to lipid progression
• —> FOAM cells release growth factors that contribute to SM cell proliferation and migrate from smooth muscle layer to INTIMA

Question 15

plaque structure?

Answer 15

an atheroma forms = atherosclerotic plaque

- aggregation of smooth muscle cells, macrophage, other WBC, collagen, elastic fibers