CVS Flashcards
three layers of the arteries
intima, media, adventitia
intima
endothelial cells, maintain permability barrier, elaborate anti/prothrombotic molecules, modulate blood flow and vascular reactivity, egulate inflammation and immunity (IL-1, IL-6, V-CAM 1/ ICAM, regulation of cell growth with PDGF and TGF beta, do oxidation of low density lipoprotein.
media
smooth muscle cells- vasoconstriction and dlation, elaboration of growth factors and cytokines, when intima is damaged it migrates to intima and proliferates. it moves across the elastic lamina to do so. when they migrate they change their phenotype to undergo division and expansion.
Adventitia
Connective tissue
Endothelial stimulation
rapid and reversible, independent of new protein synthesis, has an anticoagulant surface, low leukocyte adhesivity, produces nitric oxide
Endothelial activation
alteration in gene expression and protein synthesis- has prothrombotic surface, doesn’t produce NO, increased leukocyte activity
Endothelial activators/induced genes
cytokines/adhesion molecules, bacterial products/cytokines & chemokines, hemodynamic forces/growth factors, virus/MHC molecules.
Two principle mechanism for diseases of the blood vessels.
narrowing or complete obstruction of lumen either progressively (atherosclerosis), suddenly (thrombosis) or both (MI)
Weakening of the wall of the vessel leading to dilatation or rupture.
Athersclerosis
chronic inflammatory disorder of the intima of the large arteries characterized by formation of fibro fatty plaques called atheroma
uncertain, unquantifiable or lesser risk factors for atherosclerosis
hyper homocysteinemia (homocystinuria) this is due to a b12 or folate deficiency and uria due to genetic defect.
Lipoprotein (a) altered LDL
– inhibitors of fibrinolysis,- high PA-1 inhibitor
– C-reactive protein
C reactive protein does this
acute phase reactant, endothelial cell activator, decreased by statins/ healthy life.
Chlamydia pneumoniae
only organism that increases risk of atherosclerosis.
Non modifiable risk factors for atherosclerosis
Age- beings in childhood, 40-60 five fold increase in incidence of MI
Sex- Males greater than females if premenopausal. Favorable response to HRT.
=Genetics- familial clustering, familial hypercholesterolemia.
Hyperlipidemia
increase in cholesterol is most important due to increase risk of LDL, and decrease in HDL.
Familial haypercholesteremia
defect in LDL receptor means decrease in uptake of LDL which increases LDL levels in blood , increase in lDL could also be becasue of abnormal apeE which means it fails to bind to LDL receptor.
DM and hypothyrodism
premature and sever A.S.
Metabolic syndrome
insulin resistance dyslipidemia and pro-inflammatory state.
Evidences linking increased cholesterol with athersclerosis.
atheromas contain cholesterol and cholesterol esters, increase in LDL=increase in severit of A.S. high cholesteral diets produce experimental A.S. levels of cholesterol decrease in diet/drugs = progression of A.s.
Hypertension as risk for A.S.
after age 45 if you ahve above 170/95 you increase risk of Ischemic heart disease, antihypertensive therapy reduces incidence of A.S. associated diseases.
homocysteinuria
creates more reactive oxygen species which causes more endothelial dysfunction, proliferation of vascular smooth muscle cells, lipid peroxidation, and oxidation of LDL
Lipoprotein (a)
altered form of LDL, causes lipid accumulation, endothelial cell modulation, smooth muscle cell proliferation, control of neo vascularization.
–ApoB-100 portion of LDL + apolipoprotein A
Pathogenesis of atherosclerosis
chornic inflammatory and healing repsonse of the arterialwall initiated by some form of the injuy to the endothelium. this incorporates both dominant theories of intimal cellular proliferation and repetitive thrombus formation/organization. CRP is used to measure artherslcerosis.
Role of endothelial cell sin endothelial injury
endothelial activation causes increased permeability, adhesion of leukocytes, expression of adhesion molecules (VCAM-1) and growth factors.
determinants of endothelial alterations.
hemodynamic factors - hypertension, and increased turbulence at branch points and ostia of vesselsl.
Hypercholesterolemia- increased fats.
role of lipids in response to injury
cytotoxic to endothelium, oxidized lipids; readily ingested by macrophages form foam cells, chemotactic for circulating monocytes, inhibits the motility of macrophages already in lesion, stimulates release of growth factors and cytokines.
role of macrophages
cytockines like IL-1, TNF, growth factors.
role of smooth muscle proliferation
conversion of fatty streat to fibrofatty atheroma by secreting ECM which expands and occludes the lumen. uses collagen and smooth muscle cells.
fatty streaks
fatty dots coalesce to form fatty streaks and are composed of lipid laden macrophages, sen in children older than 10 years.
three principle components of plaque
Cells- smooth muscle, macrohpages, leukocytes,
ECM- collagen, elastic fibers, proteoglygans
Lipids-intra/extracellular
complicated lesion of A.S.
calcification(patchy or massive), focal rupture or gross ulceration leading to thrombus or emboli, hemorrhage, superimposed thrombus, aneurysmal dilatation( atrophy due to decreased oxygenation)
most common sites for athersclerosis
- distal aorta and common iliac 2. proximal coronary arteies 3. thoracic aorta, femoral and popliteal arteries, 4. internal carotid. 5. middle cerebral arteries.
A.S. clinical manifestations
CHD- acute MI, angina (stable or unstable) chronic ischemic heart disease leading to congestive heart failure, sudden cardiac death
AAA- abdominal aortic aneurysm
Cerebral vascular disease- stroke, transient ischemic attack, chronic ischemic encephalopathy
- Peripheral vascular disease- cluadication ischemic bowel disease mesenteric occlusion gangrene.
normal BP
130/85