Vascular Histology

Question 1

What branch and decrease in diameter?

branch and increase in diameter?

Answer 1

arteries

veins

Question 2

What is most internal layer of bv? And layers within it?

Answer 2

tunica intima
endothelium (1 layer squamous epithelia cells), basal lamina(endothelial cells, collagen, proteoglycans, glycoproteins), sudendothelial layer (loose ct with internal elastic membrane)

Question 3

function of internal elastic membrane

Answer 3

gives recoil

fenestrated sheet like layer of elastic material in arteries and arterioles

Question 4

Middle layer of bv? thickest in? extends to?

Answer 4

tunica media
thick in arteries to pump blood
from internal elastic membrane to external elastic mem (recoil!)

Question 5

outermost layer of bc? structure and function?

Answer 5

tunica adventitia
collagenous tissue with few elastin fibers to prevent overexpansion
more in veins than arterials
merges with CT of surrounding vessels

Question 6

Vessels that supply tunics? in what layer? thickest where?

Answer 6

vasa vasorum, tunica adventitita, veins because they carry deoxy blood only

Question 7

why is vasa vasorum need in arterioles?

Answer 7

blood flow is very fast and have large lumen, see need something else to help diffuse nutrients

Question 8

nervi vasorum

Answer 8

ans input controlling contraction of vas smooth m

Question 9

large (elastic) arteries

Answer 9

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

Question 10

medium (muscular) arteries

Answer 10

lots of smooth m and less elastin
v prominent internal elastic membrane and external elastic mem present
thick tunica adventitia

Question 11

small arteries and arterioles

Answer 11

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

Question 12

capillaries

Answer 12

metabolic exchange in cap beds
v flexible, fold on itself
have pericytes

Question 13

pericytes

Answer 13

perivascular contractile cells w branches of cytoplasmic processes, surround vessel and contract
controlled by NO (endothelial cells)
stability of cap and postcap venules

Question 14

endothelial cells

Answer 14

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)

Question 15

continuous cap

Answer 15

most common, tight occluding jxn, exchange via diffusion or transcytosis, cont bm, everywhere, continuous = cells meet end to end

Question 16

fenestrated cap

Answer 16

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)

Question 17

discontinuous/sinusoidal cap

Answer 17

exchanging of macromol and cells opening
larger fenestration and large open exchange, partial/discont bm
bone marrow, liver, spleen

Question 18

order of arterial to venous end

Answer 18

metarterioles -> precapillary sphincters->true capillaries->thoroughfare channel -> postcapillary venule

Question 19

true capillaries have and lack?

Answer 19

lack smooth m, pericytes must be present

thoroughfare channel las smooth m too

Question 20

what regulates blood flow through true capillaries?

Answer 20

precapillary sphincters

can force blood to enter venous more quickly depending on metabolic demand

Question 21

order of veins

Answer 21

cap -> (postcap) venules-> m venules -> small veins -> medium (majority) -> large (svc/ivc/hepatic portal vein)

Question 22

tunics of veins?

Answer 22

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

Question 23

postcap venules, m venules, small veins, large veins

Answer 23

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

Question 24

med veins travel w?

Answer 24

muscular arteries

Question 25

why does fluid leak out of cap bed and walls? what collects the leaky fluid to go back to back into the venous system?

Answer 25

lymphatic vessels cleans and returns

pressure gradient is strong, pushes fluid out

Question 26

lymphatic cap

Answer 26

closed end tubes in cap beds with 1 way valves for collecting lymph, incomplete basal lamina for permeability,
openings in endothelial by anchoring filaments

Question 27

lymphatic cap connect to?

Answer 27

collecting lympathic vessels

have tunic and valves with tight jxn

Question 28

lymph flow?

Answer 28

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