Vascular Histology Flashcards
What branch and decrease in diameter?
branch and increase in diameter?
arteries
veins
What is most internal layer of bv? And layers within it?
tunica intima
endothelium (1 layer squamous epithelia cells), basal lamina(endothelial cells, collagen, proteoglycans, glycoproteins), sudendothelial layer (loose ct with internal elastic membrane)
function of internal elastic membrane
gives recoil
fenestrated sheet like layer of elastic material in arteries and arterioles
Middle layer of bv? thickest in? extends to?
tunica media
thick in arteries to pump blood
from internal elastic membrane to external elastic mem (recoil!)
outermost layer of bc? structure and function?
tunica adventitia
collagenous tissue with few elastin fibers to prevent overexpansion
more in veins than arterials
merges with CT of surrounding vessels
Vessels that supply tunics? in what layer? thickest where?
vasa vasorum, tunica adventitita, veins because they carry deoxy blood only
why is vasa vasorum need in arterioles?
blood flow is very fast and have large lumen, see need something else to help diffuse nutrients
nervi vasorum
ans input controlling contraction of vas smooth m
large (elastic) arteries
biggest, elastin concentric lamellae/sheets between m layers
NO FIBROBLAST to pump and stretch
lumen size lets high pressure and strong blood flow to cont in diastole
medium (muscular) arteries
lots of smooth m and less elastin
v prominent internal elastic membrane and external elastic mem present
thick tunica adventitia
small arteries and arterioles
sa - 8 smooth m layers, w internal elastic mem
arterioles - 1-2 layers, w or wo internal elastic mem, flow regulators for capillary beds (slower), sym inner tunica media (vasoconstrict), ps inner vasodilation
capillaries
metabolic exchange in cap beds
v flexible, fold on itself
have pericytes
pericytes
perivascular contractile cells w branches of cytoplasmic processes, surround vessel and contract
controlled by NO (endothelial cells)
stability of cap and postcap venules
endothelial cells
innermost of tunica intima via cell-cell jxn (# dep on permaability)
support bm and make collagen, involve w pilates bodies (storage for coag, thrombosis, local vasodilate/contstrictors)
continuous cap
most common, tight occluding jxn, exchange via diffusion or transcytosis, cont bm, everywhere, continuous = cells meet end to end
fenestrated cap
mol exchange organs where blood important
tight jxn w fenestrations in endo cells = great exchange w limit size of macromol, cont bm, endo glands, fluid/metablotie absorption (gallb, kid)
discontinuous/sinusoidal cap
exchanging of macromol and cells opening
larger fenestration and large open exchange, partial/discont bm
bone marrow, liver, spleen
order of arterial to venous end
metarterioles -> precapillary sphincters->true capillaries->thoroughfare channel -> postcapillary venule
true capillaries have and lack?
lack smooth m, pericytes must be present
thoroughfare channel las smooth m too
what regulates blood flow through true capillaries?
precapillary sphincters
can force blood to enter venous more quickly depending on metabolic demand
order of veins
cap -> (postcap) venules-> m venules -> small veins -> medium (majority) -> large (svc/ivc/hepatic portal vein)
tunics of veins?
not as defined, med and large have all 3, tunica intima has valves of thin ct covered with endothelial cells to prevent backflow
thin walls! lumen large and can collapse, skeletal m pump blood to heart
postcap venules, m venules, small veins, large veins
pv - no true tunica media
mv - 1/2 layers of smooth m
s - 3 tunics, 2/3 layers
l-2/15 layers w collagen and elastic fibers, ct
med veins travel w?
muscular arteries
why does fluid leak out of cap bed and walls? what collects the leaky fluid to go back to back into the venous system?
lymphatic vessels cleans and returns
pressure gradient is strong, pushes fluid out
lymphatic cap
closed end tubes in cap beds with 1 way valves for collecting lymph, incomplete basal lamina for permeability,
openings in endothelial by anchoring filaments
lymphatic cap connect to?
collecting lympathic vessels
have tunic and valves with tight jxn
lymph flow?
lymphatic cap -> afferent lymphatic vessels -> lymph nodes (cleans!)-> efferent lymphatic vessels
-> lymphatic trunks -> r lymphatic duct ( r head, neck, ue, thorax) -> thoracic duct -> brachiocephalic v -> svc
