Vascular Disease Flashcards
What disease causes more morbidity and mortality than any other group of diseases?
Vascular disease
List the two major mechanisms of vascular disease
- Narrowing/Obstruction
-Acutely (thrombosis/embolism)
-Progressively (atherosclerosis) - Weakening - causes dilation and/or rupture
Describe the composition of vessels
-Endothelial cells (EC)
-Smooth muscle cells (SMC)
-ECM - elastin, collagen, glycosaminoglycans
What are the layers of the vessel wall?
- Intima - single layer of EC cells
- Internal elastic lamina
- Media - SMC
- External elastic lamina
- Adventitia - contains vessels (vasa vasorum) providing nutrients for the vessel itself
List the different types of arteries
- Large (elastic)
-Aorta, subclavian, common carotid, iliac, pulmonary - Medium (muscular)
-Coronary, renal - Small (<2mm) and arterioles
-Arterioles are the main control point for regulation of resistance to blood flow (regulates bp) - Capillaries - no media, diffusion of nutrients
List the different types of veins
- Post-capillary venules
-site of vascular leakage in inflammation - Collecting venules
- Larger veins
How do veins compare to arteries?
Veins are…
-Larger diameter, larger lumina, thinner/less organized walls
-More prone to dilation/compression and penetration by tumors or inflammation (b/c larger diameter and thinner walls)
Describe the features of lymphatics
Thin-walled, endothelium-lined channels that drain lymph (water, electrolytes, glucose, fat, proteins and inflamnatory cells) from interstitum back to heart and to lymph nodes
What is the purpose of lymphatics?
-Maintain blood volume
-Facilitate antigen presentation/immune activation
List the functions of the endothelium (6)
- Lines vascular system, maintains hemostasis
- Diffusion of small molecules (nutrients, electrolytes and O2) but not larger molecules (proteins)
- Balances coagulation (vWF, tissue factor, plasminogen activator inhibitor) vs. anticoagulation (prostacyclin, thrombomodulin, heparin-like molecules, plasminogen activator)
- Balances vasoconstriction (endothelin, ACE) vs. vasodilation (NO, prostacylin)
- Regulates inflammation (i.e. IL-1, IL-6, chemokines)
- Regulates growth- stimulates (e.g. PDGF, CSF, FGF) vs. inhibits (TGF-beta)
What happens with endothelial activation?
- Shape changes
- Express adhesion molecules and produce:
-cytokines
-chemokines
-growth factors
-procoagulant and anti-coagulant factors
T/F: Endothelial activation can be rapid (minutes), reversible with no new protein synthesis, or take days to develop due to gene/protein expression changes
TRUE
Why does the endothelium get activated?
Response to stimuli (with intent to respond appropriately):
-Bacterial products
-Inflammatory cytokines
-Hemodynamic stresses
-Lipid products (in atherosclerosis)
-Advanced glycation end products (in diabetes)
High levels of stimuli for sustained periods can cause endothelial dysfunction with….
-Endothelium -dependent impaired vasodilation
-Hypercoagulability
-Increased ROS (causing cell injury and cell death)
What does endothelial dysfunction increase the risk of?
Thrombosis, promotes atherosclerosis, hypertension and diabetes
What are the functions of the Media?
- Elastic recoil in large arteries allows pulsatile flow
- Smooth muscle in arterioles, small and medium arteries regulates resistance
When any insult or dysfunction occurs in the media, _________ are released leading to:
Growth factors are released leading to:
Smooth muscle cell (SMC) migration into the intima and proliferation leading to intimal thickening
-Aids in repair (good)
-Involved in atherosclerosis (bad)
SMCs that migrate into the intima don’t have contractile properties but they can _______
divide
In the media, with persistent insult –> excessive intimal thickening –> _______
stenosis
How do you calculate BP?
BP = cardiac output x peripheral resistance (how dilated the vessel is)
**BP maintenance required for adequate organ perfusion
When BP or blood Na+ decreases, _____ is secreted. What is the result of this?
Renin
-Increased vascular tone and increased aldosterone secretion, both of which increases BP
What is Stage 1 hypertension?
> 130/80 mm Hg
What is Stage 2 hypertension?
> 140/90 mm Hg
What is the pathophysiology of hypertension?
Increased cardiac output and/or peripheral resistance in small vessels causes hypertension
What is the cause of 90-95% of all hypertension cases?
No known cause “idiopathic”
Describe the Pathogenesis Theory of essential hypertension (primary)
-Multiple genetic and environmental factors which increase blood volume (due to reduced renal sodium excretion) and/or peripheral resistance (vessel wall tone/structure)
-Environmental factors - stress, obesity, smoking, lack of exercise, heavy salt intake
List the secondary causes of hypertension. Which of these is the biggest contributor?
-Kidney disease*
-Pheochromocytoma
-Cushing syndrome
-Conn syndrome
-Hyperthyroidism
-Pre-eclampsia
*Kidney disease is the biggest contributor
How does kidney disease contribute to hypertension
Producing renin –> angiotensin I –> angiotensin II –> Na reabsorption and vasoconstriction
How does Pheochromocytoma contribute to hypertension
Adrenal tumor making catecholamines
How does Cushing syndrome contribute to hypertension
Adrenal cortex tumor that makes corticosteroid
How does Conn syndrome contribute to hypertension
Adrenal cortex tumor that makes aldosterone
How does Hyperthyroidism contribute to hypertension
Produces thyroxin that raises BMR
How does Pre-eclampsia contribute to hypertension
Endothelial dysfunction during pregnancy leading to vasoconstriction
What are the consequences of Hypertension?
- Thickening of small arteries and arterioles with luminal narrowing (arteriolosclerosis) –> nephrosclerosis (scar tissue in the kidney as a result of chronic low blood flow)(an ischemic kidney disease)
- Accelerated atherosclerosis
- Weakens vessel wall leading to
-dissecting aneurysms
-cerebral hemorrhage - Left ventricular overload –> hypertrophy –> failure
What is the normal vascular response to injury? What happens if persistent and recurrent injury occurs?
Normal:
-Vascular injury –> endothelial loss or endothelial cell dysfunction –> smooth muscle cell growth and matrix synthesis –> intimal thickening
Persistent and recurring injury:
–> further thickening results leading stenosis (narrowing) - now pathologic
Definition of Arteriosclerosis
“Hardening of the arteries” associated with intimal thickening, decreased luminal size and loss of elasticity
List the major types of arteriosclerosis
- Arteriolosclerosis
-vessel wall thickening
-associated with hypertension and diabetes - Atherosclerosis
-intimal thickening of large and medium arteries
In atherosclerosis, ________ obstructs blood flow
Intimal plaque
-Consists of necrotic lipid core (mostly cholesterol) with a fibromuscular cap; often undergoes dystrophic calcification
What type of arteries does atherosclerosis affect? Where in the artery is usually affected?
Large and medium sized arteries, especially at bifurcations
-Abdominal aorta, coronary, popliteal, internal carotid are commonly affected
List the modifiable major risk factors of atherosclerosis
-Hypertension
-Hyperlipidemia (specifically hypercholesterolemia)
-Smoking
-Diabetes
List the non-modifiable major risk factors of atherosclerosis
-Age (# and severity of lesions increases with age)
-Gender: increased risk in males and postmenopausal females; estrogen is protective
-Genetics: multifactorial, but family history is strongest independent risk factor
Give an overview of Hyperlipidemia
-Lipids are bound to apoproteins in blood
-Defective apoproteins or lipid receptors can increase LDL and decrease HDL
-Prefer total cholesterol to be <200 mg/dL
Describe HDL (high density lipoprotein)
-“good cholesterol”
-Takes cholesterol from tissues/atheromas and transports to liver for excretion in bile
Describe LDL (low density lipoprotein)
-“bad cholesterol”
-Delivers cholesterol to peripheral tissues