Vascular Biology I Flashcards
What are the two components of vascular biology?
1) blood vascular system
2) lymphatic vascular system
What are the three layers of blood vessels in order from innermost to external?
tunica intima -> tunica media -> tunica adventitia
What are the two layers of the tunica intima?
1) Endothelium and basal lamina
2) Subendothelial layer
Where is the internal elastic lamina located?
Within the subendothelial layer of the tunica intima
What are the components of the subendothelial layer?
1) loose connective tissue
2) scattered fibroblasts and occasional smooth muscle cells (in arteries)
3) internal elastic lamina
What is the internal elastic lamina composed of?
Fenestrated elastin
Where would you find concentric layers of smooth muscle cells?
Within the tunica media
What four substances are found within the tunica media?
Elastin: fibronectin and fibrillin-1
Reticular fibers
Proteoglycans
Where would you find the external elastic membrane?
Tunica media
What are the three components of the tunica adventitia?
Type I collagen fibers
Elastic fibers
Fibroblasts
Which layer is the connective tissue layer?
Tunica adventitia
What does vasa vasorum mean?
vessels of the vessels
What is the difference between arteries and veins in terms of vasa vasorum?
Veins are more deeply penetrated by vasa vasorum because they carry deoxygenated blood and the oxygen and nutrients are needed deeper than they are needed in oxygen carrying arteries
Which vessels require vasa vasorum?
Vessels greater than 1 mm in diameter
What happens to vasa vasorum in atherosclerosis?
the vasa vasorum contribute to the angiogenesis and inflammation of the diseased vascular wall
- includes intimal thickening
What happens to the vasa vasorum of the ascending aorta in syphilis?
the vasa vasorum of the ascending aorta becomes inflamed in syphilis
Results in endarteritis and periarteritis of the vasa vasorum –> obliteration
What causes a ‘tree bark’ appearance to be imprinted on the intimal surface?
Focal necrosis and scarring of the media and degeneration of the elastic lamellae due to syphilis results in depressions observed on the surface of the initima: “tree bark”
What is the innervation to blood vessels called?
nervi vasorum/vascularis
Do nerve endings found in the adventitia of arteries penetrate the media?
NO
Where are the nerve endings of nervi vasorum found in veins?
adventitia and media layers
- less dense than arteries
True or False: Nervi vasorum nerve fibers to blood vessels are mainly parasympathetic.
FALSE
Nerve fibers are mainly SYMPATHETIC
A few vascular bed may also receive parasympathetic fibers
Describe endothelial cells
Flattened
Polygonal
Long axis in direction of blood vessel
What junctions does an endothelial cell have?
1) Between endothelial cells and basal lamina
2) Myoedothelial: between muscle cell and endothelium
What causes endothelial cell hyperpolarization? What is the net result?
Shear stress exerted by blood flow produces endothelial cell hyperpolarization.
This is conducted to vascular smooth muscle via gap junctions causing their hyperpolarization. Net result is vasodilation.
What cells contain weibel-palade bodies?
Endothelial cells contain weibel-palade bodies
What 5 things do weibel-palade bodies contain?
1) Von Willebrand factor (coagulating factor VIII)
2) Tissue plasminogen activator
3) Interleukin 8
4) P-selectin
5) Others
What are 5 functions of endothelial cells?
1) Promote/inhibit blood coagulation [prtn S inhibits blood clotting]
2) Modulate smooth muscle activity [endothelin and NO]
3) Regulate inflammatory cell traffic
4) Transport numerous pinocytotic vesicles
5) Regulate angiogenesis
Describe high pressure blood vessels.
Lots of smooth muscle and elastic elements
Describe smaller arteries.
Prevalence of smooth muscle, less elastic than larger arteries.
Describe veins.
Lots of connective tissue.
Larger veins will have a bit of elastin.
Which is thicker: artery or vein?
Artery
You see a lot of elastic tissue. What blood vessel are you looking at?
Arterial
Where would you see alternating layers of elastin and smooth muscle?
Aorta
Would you expect to find a fibroblast in the tunica media?
NO
There are typically not fibroblasts in the tunica media, the components of the tunica media are synthesized by smooth muscle cells
In large, elastic arteries, will elastic lamellae increase, decrease, or stay the same with age? What are the other effects of aging?
Elastic lamellae increase with age
Aging also causes mild to moderate intimal fibrosis and fragmentation of elastic lamellae in the media
What is the effect of Marfan’s syndrome on large arteries?
severe elastic medial fragmentation with GAG area “lakes of mucopolysaccharides’
How does aging change muscular/medium arteries?
Progressive intimal fibrosis (thickening) and alterations of elastic elements
What are metarterioles? What is their purpose?
Vessels between arterioles and capillaries
Help to regulate blood flow into the capillary bed
What is the media of meatarterioles composed of>
A discontinuous layer of smooth muscle
Which blood vessel has a one-to-one wall-to-lumen ratio?
Arterioles
The wall thickness should be approximately equivalent to the diameter of the lumen
Do capillaries have a tunica adventitia?
NO
This would just get in the way
Do capillaries have a true tunica media?
NO
Pericytes relate to the position of this layer
What is one of the functions of pericytes?
Pericytes are contractile, they also contribute to the formation of scar tissue in the CNS and perhaps in other organs
What type of cells are pericytes?
Mesenchymal cells
Can transform into smooth muscle cells and fibroblasts
What are the three types of capillaries?
Continuous
Fenestrated
Sinusoidal
Where are continuous capillaries located?
CNS
muscle
lungs
Where are fenestrated capillaries located?
Kidney
Intestines
Endocrine glands
Where are sinusoidal capillaries located?
Spleen
Liver
Bone marrow
Where do most aneurysms occur?
At points of branching or bifurcation (weak points)
Occur at areas where there is a gap in the circular muscle layer at bifurcation
