Vascular bio II Flashcards
What are the three types of capillaries?
Continuous
Fenestrated
Sinusoidal
What type of junction exists between cells of a continuous capillary?
Tight junctions (zonulae occludens)
If a ZO is incomplete, what is it then called?
Fascia occludens
What is the fold that covers up the tight junctions between the cells of continuous capillaries?
Marginal fold
What is present in large amounts in the cytoplasm of continuous capillaries?
Pinocytotic vesicles
How are transendothelial channels formed in continuous capillaries?
Fusion of many pinocytotic vesicles
Where are continuous capillaries found?
Brain Lung Muscle CT Exocrine glands
anywhere where you want specific transport
What are the two types of fenestrated capillaries?
With and without a diaphragm
True or false: the basal lamina is discontinuous in fenestrated capillaries?
False
Where are fenestrated capillaries found?
Kidney
Endocrine glands
Intestines
Glomerulus (diaphragms absent here)
Anywhere where movement of ions is preferred
Do most fenestrated capillaries have diaphragms?
Yes, most do
What is different about the basal lamina in sinusoidal capillaries?
either very discontinuous or absent
Where are sinusoidal capillaries found?
Red bone marrow
Liver
Spleen
Adrenal cortex
Wherever rapid movement is needed
What are the two types of venules?
Pericytic and muscular venules
Where do leukocytes attach in veinules?
At the marginal fold
Why is the tunica media thin in veinules?
Low pressure
What is the thickest layer of veinules?
the tunica adventitia
What are present in veins that are entirely absent in arteries?
valves
What are present in arteries that are entirely absent in veins?
Lamellae
What is characteristic of medium veins, as compared to smaller veins?
Small amount of smooth muscle
What is the defining characteristic of large veins?
Bundles of longitudinally smooth muscles in he tunica adventitia (NOT the tunica media)
What is vasculogenesis?
de novo vessel formation
What is angiogenesis?
Growth of vessels from existing EC derived channels
What is arteriogenesis?
Formation of arteries, arterioles, and collateral vassel remodeling
What is neovascularization?
overarching term to include the three genesis terms
What is remodeling (in terms of vessels)?
vascular response to alterations in the environment
Where are endothelial cells precursors found?
In red bone marrow
What are endothelial cepp precursors?
angioblast-like cells that reside in the red bone marrow of adults and non-bone marrow niches
What are the three functions of EPCs?
- Replaces lost endothelial cells
- Re-endothelization of vascular implants (stents)
- Neovascularization of ischemic organs, wounds, and tumors
What is the first step of angiogenesis?
Vasodilation due to NO and increased vascular permeability induced by VEGF of pre-existing (parent) vessel
What is the second step of angiogenesis?
Proteolytic degradation of the basal lamina of the parent vessel by metalloproteinases. Endothelial cells must shed their cell-to-cell contacts (intercellular junctions). This loss of cell-to-cell contact is mediated by plasminogen activator.
What is the third step of angiogenesis?
Migration and proliferation of endothelial cells which have disrupted their cell-to-cell contacts. The migration and proliferation is induced by proangiogenic factors (e.g., VEGF and angiopoietin 2). Fibroblast growth factor-2 can also mediate endothelial cell migration and proliferation.
What is the fouth step of angiogenesis?
Endothelial cells mature into an endothelial capillary tube.
What is the fifth step of angiogenesis?
Elaboration of basal lamina and recruitment of periendothelial cells. Elaboration of basal lamina elements is mediated by TGF-β (transforming growth factor). Recruitment of periendothelial cells is mediated by the interaction of Ang 1 with the Tie2 receptor on endothelial cells. PDGR (platelet-derived growth factor) induces recruitment of smooth muscle cells. Angiopoietin (Ang) 2 is involved in the remodeling process by blocking the stabilizing action of Ang
What is the function of ANG 2?
Destabilizes vessels in the third step of angiogenesis
What is the function of VEGF?
Increase the permeability of vessels in the first step of angiogenesis
What is the function of metalloproteases?
Enzymes that degrade the basal lamina in the second step of angiogenesis
What is the function of plasminogen activator?
Disrupts the intercellular junctions of the basal lamina in the second step of angiogenesis
What is the precursor for the formation of vessels?
Capillary tubes formed by endothelial cells
What is the function of TGF-beta
Elaborates the basal lamina of newly formed capillary tubes
What is the function of ANG-1?
Stabilizes newly forming vessels
What is the function of FGF-2?
Works with VEGF and causes unstable vessel endothelial cells to prolifeerate and migrate to the signal
What is the function of tie2 receptor?
Expressed on the surface of endothelial cells, and binds to ANG-1
This then recruits smooth muscle cells or pericytes
Is proangiogenesis or antiangiogenesis used for: MI?
Pro
Is proangiogenesis or antiangiogenesis used for:peripheral ischemia?
Pro
Is proangiogenesis or antiangiogenesis used for:tumor growth and metastases?
ANti
Is proangiogenesis or antiangiogenesis used for: ocular nerve neovascularization?
Anti
Is proangiogenesis or antiangiogenesis used for:birth control?
anti
Is proangiogenesis or antiangiogenesis used for: transplantation of islets of langerhands?
pro
Is proangiogenesis or antiangiogenesis used for: reconstruciv surgery?
Pro
Is proangiogenesis or antiangiogenesis used for: would healing?
pro
Is proangiogenesis or antiangiogenesis used for: atheroscleotic plaque neovascularization?
Anti
Is proangiogenesis or antiangiogenesis used for: hemangiomas?
anti
Is proangiogenesis or antiangiogenesis used for: cerebral ischemia?
Pro
Is proangiogenesis or antiangiogenesis used for: DM ulcers?
Pro
What is tumor endothelial marker 8? What is its clinical significance?
Chemical expressed only by tumor cells. Allows for targeting of these tumors via antiangiogenesis
Why is the great saphenous vein used in CABGs?
Its tunica media is much thicker than other veins d/t two muscle layers
What happens to the great saphenous vein after it is used for a CABG?
undergoes thickeing