• Narrowing (stenosis) or complete obstruction of blood vessels lumens, either progressively (e.g., by atherosclerosis) or precipitously(e.g., by thrombosis or embolism)
• Weakening of vessel walls, leading to dilation or rupture
What is normal vascular structure??
Arterial walls are thicker than corresponding veins at the same level of branching to accommodate pulsatile flow and higher blood pressures.
Basic constituents of the walls of blood vessels —
– Endothelial cells (ECs)
-smooth muscle cells (SMCs)
-Extracellular matrix (ECM) including elastin, collagen, and. glycosaminoglycans.
Arteries and veins, these constituents are organized into three concentric layers—
1..Tunica intima [ single layer of ECs+basement membrane]
( basement membrane form by thin underlying layer of ECM)
2..internal elastic lamina
3..Tunica media
what is the composition of Tunica media in different arteries ??
4..External elastic lamina
5..Tunica adventitia/ Tunica externa
which are anatomically more distinct in the arteries.
what is the types of arteries ???
VACULAR ANOMALIES
Four are particularly significant..
1.Developmental or berry aneurysms
2.Arteriovenous fistulas are direct connections (usually small) between arteries and veins that bypass capillaries
3.Fibromuscular dysplasia is a focal irregular thickening in medium and large muscular arteries including renal, carotid, splanchnic, and vertebral vessels.
4.Anomalous coronary artery origin occurs from a developmentalanomaly in which both coronary arteries arise over the same coronary cusp of the aortic valve.
VASCULAR WALL RESPONSE TO INJURY
The integrated functioning of ECs and SMCs impacts physiologic and pathophysiologic responses to hemodynamic and biochemical stimuli.
- ECs Form a specialized simple squamous epithelium lining for blood vessels.
- ECs throughout the vascular tree share many properties
- But ECs that line different portions of the vascular tree ( large vessels vs. capillaries, arteries vs. veis) have sdifferent gene expression,behaviors and morphological appearances.
EXAMPLE..
Liver sinusoids or in renal glomeruli are fenestrated
while central nervous system ECs( along with perivascular cells) form an impermeable blood brain barrier.
Endothelial cell properties and functions …
