3.2.3. Vascular Pathology Part 1 of 3 Flashcards
What is the tunica intima comprised of? What separates it from the tunica media?
tunica intima: single layer of endothelial cells sitting on a basement membrane (underlain by thin layer of ECM -extracellular matrix)
separated from media by internal elastic lamina
Compare the tissue of arteries and veins with respect to their organization on the tissue level
arteries: well-organized, concentric layers of smooth muscle
veins: larger diameters & lumens, with thinner & less organized walls than arteries at the same level of branching
What are large arteries also called and why?
(large) elastic arteries (e.g. aorta): high elastin content
What are our medium arteries and what affects their size?
(medium) muscular arteries: predominantly composed of circumferentially oriented SM cells
autonomic input varies the degree of vasodilation/-constriction
What type of arteries are affected most by blood flow resistance and what affects this resistance the most?
(small) arterioles: principal points of physiologic resistance to blood flow (autonomic changes to lumen diameter profoundly affect amount of resistance)
What are capillaries?What layer of tissue is missing from capillaries that is present in arteries?
capillaries: endothelial lining without media
Where is the tunica adventitia and what comprises it? What separates it from the preceding layer?
tunica adventitia: external to media; usual separated by the external elastic lamina
consists of loose connective tissue containing nerve fibers and vasa vasorum
What do all vessels have in common as far as layers? As review, what comprises these layers?
all vessels except capillaries share a three-layered architecture consisting of an endothelium-lined intima, a surrounding smooth muscle media, & supportive adventitia, admixed with extracellular matrix
What are our congenital vascular anomalies?
developmental or berry aneurysms
arteriovenous fistulas
fibromuscular dysplasia
Describe developmental or berry aneurysms. Where do they occur and what do they do?
occur in cerebral vessels
when ruptured can cause fatal intracerebral hemorrhage
Where do we see arteriovenous fistulas and what can rupture lead to?
direct connections between arteries and veins that bypass the intervening capillary bed
can rupture leading to intracerebral hemorrhage
Describe fibromuscular dysplasia
focal, irregular thickening in med. & lg. muscular arteries
- combined medial & intimal hyperplasia as well as fibrosis which results in luminal stenosis
- immediately adjacent vessels can have markedly attenuated media → vascular outpouchings (aneurysms) that can rupture. Has a “string of beads” appearance on angiography
What are the synthetic and metabolic properties of endothelial cells?
nonthrombogenic surface, modulate medial SM cell tone, metabolize hormones, regulate inflammation, affect growth of other cell types (particularly SM cells)
Effect of cytokines and bacterial products on endothelial cells
elicit inflamm.; extreme: septic shock
Effect of hemodynamic stresses & lipid products on endothelial cells
pathogenesis of atherosclerosis
Effect of advanced glycation end-products on endothelial cells
pathogenesis of diabetes
What 5 items activate endothelial activation?
Normotension Laminar Flow Growth Factors Cytokines Hypoxia/Acidosis
When you activate an endothelial cell what happens?
Stimulates: Growth factors Vasoactive mediators Adhesion molecules Anti-coagulants
Endothelial dysfunction can cause what?
Release of: Growth factors (like with normal activation) Chemokines Cytokines Pro-coagulant proteins Adhesion molecules Vasoactive mediators
What do vascular smooth muscle cells synthesize?
synthesize collagen, elastin, and proteoglycans, elaborate growth factors, & cytokines
responsible for vasodilation/-constriction
Effect of vascular injury on a vessel?
Vascular injury- associated with endothelial cell dysfunction or loss- stimulates smooth muscle cell recruitment and proliferation and associated matrix synthesis; the result is intimal thickening
Excessive thickening of the intima results in what?
excessive thickening of the intima may result in luminal stenosis and vascular obstruction
What can hypotension do to the body?
Hypotension can result in inadequate organ perfusion and can lead to tissue dysfunction and death.
What can hypertension do to the body? What percent of Americans are affected by it?
Hypertension (HTN) can cause end-organ damage and is one of the major risk factors for atherosclerosis, CHF and renal failure. Hypertension is a common disorder affecting roughly 30% of adults in the U.S.
Increased risk of atherscelerotic disease is associated with sustained diastolic pressures above ___ mm Hg or sustained systolic pressure above ___ mm Hg.
Increased risk of atherscelerotic disease is associated with sustained diastolic pressures above 89 mm Hg or sustained systolic pressure above 139 mm Hg.
95% of hypertension is of unknown etiology and is referred to as _______ _______. aka _______ _______.
95% of hypertension is of unknown etiology and is referred to as primary hypertension. aka essential hypertension
Risk factors of HTN
Risk factors include age, race (increased risk in African American, decreased risk in Asians), obesity, stress, lack of physical activity, and high-salt diet.
5% of hypertension is of known etiology and is called _____ _____.
5% of hypertension is of known etiology and is called secondary hypertension.
Common cause of secondary HTN
Renal artery stenosis is a common cause (renovascular hypertension)
What does stenosis do to the kidney?
Stenosis decreases blood flow to the glomerulus.
Once bloodflow is reduced to the glomerulus, what happens?
Juxtaglomerular apparatus (JGA) responds by secreting renin, which converts angiotensinogen to angiotensin I.
What does ACE do?
Angiotensin I is converted to angiotensin II by angiotensin converting enzyme (ACE).
What does Angiotensin II do?
Angiotensin II raises blood pressure by:
Contracting arteriolar smooth muscle, which increases total peripheral resistance
Promoting adrenal release of aldosterone, which increases resorption of sodium in the distal convoluted tubule.
What does increased blood pressure do to the kidneys?
Leads to hypertension with increased plasma renin and unilateral atrophy (due to low blood flow) of the affected kidney. Neither of these features is seen in primary hypertension.
Gene defects affecting enzymes involved in aldosterone metabolism ⇒ leads to what?
Gene defects affecting enzymes involved in aldosterone metabolism ⇒ lead to increased aldosterone secretion, increasing salt and water resorption
What is Liddle Syndrome and what kind of mutation is it?
Mutations affecting proteins that influence sodium reabsorption; moderately severe form of salt-sensitive hypertension is called Liddle syndrome (gain-of-function mutation).
