Vasculature II Flashcards
What is present at junction of endothelial cells
intracellular junction
either ZO or interrupted incomplete fascia occludens. One cell with have marginal fold
Why do pinocytotic vesicles have a large volume
tight junctions
vesicles can fuse, forming continuous temporal channels which allows for movement from lumen to ECM
How to tell if it’s a continuous capillary
junctional complex (dark line) with marginal fold covering connection lots of pinocytotic vesicles
How to tell if it’s a fenestrated capillary w/o diaphragms
lots of fenestrations
Where are fenstrated capillaries without diaphragms found
glomerular capillaries of kidney
How to tell if it’s a fenestrated capillary with diaphragms
you can see the diaphragms
some pinocytotic vesicles, but not as many
Where are fenestrated capillaries with diagpragms found
glomerular capillaries in kidney, elsewhere in kidney, intestines, endocrine organs
How to tell if it’s a sinusoidal capillary
larger in diameter
huge pores
no basal lamina
Where are sinusoidal capillaries found
bone marrow, liver, spleen, adrenal cortex
Pericytic venules
bound in microcirculation, have pericytes
Muscular venules
largger than percytic. Have smooth muscle in tunica media
How to tell if it’s a pericytic venule
large lumen, thin wall
nuclei is dark blue, flattened
Movement of lymphocyte
- Recognize adhesion molecules
- Attached to endothelium at region of marginal fold
- Disrupt junctional complex
- Moves between endothelial cell junction
- cross cell wall and enters ECM
Small Vein
muscle in tunica media
Tunica adventitia collagen fibers thickest
Medium vein
smooth muscle, elastic elements, and connective tissue present
connective tissue predominates
Large vein
tunica adventitia contains lontiudinally arranged smooth muscle bundles
Thin tunica media
thick tunica adventitia
Vaculogenesis
de novo vessel formation - make vessels from scratch
Angiogenesis
growth from existing EC-derived channels
Arteriogenesis
formation of arteries, arterioles, and collateral vessel remodeling
Neovascularization
overaching term. Refers to vasculogensis, angiogenesis, and arteriogenesis
Remodeling
vascular response to alterations in environment
Endothelial precursor cells (EPC)
Bone marrow is the #1 source of this. Non-bone marrow niches exist and are mobilized in response to alterations in environment
Function of vasculogenesis in adults
replace lost endothelial cells
re-endotheliazation of vascular implants
Neobascularization of ischemic organs, wounds, tumor
Angiogenic steps
1) vasodilation (NO) and icnreased permeability
(VEGF)
2) degrade basal lamina by matrix metalloproteases and disrupt intercellular junction by plasminogen activator
3) ANG-2 destabilizes vessels
4) Migration and proliferation of endothelial cells mediated by VEGF and GFG
5) Form endothelial capillary tube
6) Elaboration of basal lamina by TGF-beta and recruitment of periendothelial cells mediated by ANG-1-TIE-2 and PDGF
ANG-2
destabilizes
ANG-1
stabilizes
Vasodialation and increased permeability of vasculature
Endothelial cells attach to basal lamina and form junctional complexes with other endothelial cells
NO and VEGF cause vasodilation and increased permeability
Basal lamina disruption
matrix metalloproteases (MMPs) degrade basal lamina, separate it from endothelial cells
Disruption of endothelial cell junction complexes
plasminogen activator disrupts interceullar endothelial cell junctions
Proliferation and migration of endothelial cells
in presence of VEGF adn FGF-2, endothelial cells from pre-existing vasculature proliferate and migrate
Formation of endothelial capillary tubes
Endothelial cells form capillary tubes, delicate precursor vessels
Clinical Benefit of proangiogensis
myocardial, peripheral, and cerebral ischemia
wound healing and fracture repair
reconstructive surgery
transplatation of islets of Langerhans
Clinical benefit of antiangiogensis
tumor growth and metastases ocular neovascularization hemangiomas rhematoid arthritis atherosclerotic plaque neovascularization birth control
What is different about great saphenous vein
tunica intima has endothelium plus basal lamina, subendothelium, poor developed IEM.
tunica media has 2 or 3 muscle layers