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RC Test 2 > B4.020 Cell Biology and Histology of the Vascular System > Flashcards

B4.020 Cell Biology and Histology of the Vascular System Flashcards

1
Q

what type of epithelial cells make up the vascular epithelium?

A

simple squamous cell apithelim

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2
Q

major vessels of the cardiovascular system

A 
large (elastic artery)
medium (muscular artery)
small artery (arteriole)
capillary
venule
medium and large veins
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3
Q

discuss variations in BP between arterial and venous systems

A

heart bumps blood in a pulsatile fashion
higher pressure during systole, lower during diastole
arterial pressure pushes blood into capillaries and venous return system and then BP falls dramatically

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4
Q

layers of artery walls

A
  1. tunica intima (innermost)
  2. tunica media (middle)
  3. tunic externa/adventitia (outermost)
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5
Q

what is internal elastic lamina made up of

A

discontinuous elastic fibers

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6
Q

what is vasa vasorum

A

small blood vessels to nourish the outer layers of a thick blood vessel ( only present in the largest vessels)

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7
Q

tunica intima

A

lining of endothelial cells, subendothelial basement membrane and loose connective tissue, dense layer of elastic fibers (internal elastic fibers)

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8
Q

tunica media

A

concentric layers of smooth muscle, collagen fibers, discontinuous plates of elastic sheaths (external elastic lamina)

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9
Q

tunica externa (adventitia)

A

connective tissue

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10
Q

relate the structure and function of the large elastic arteries

A

have many elastic lamellae in the media
receive blood from heart under high pressure
walls distend during systole and recoil during diastole thereby sustaining a continuous blood flow despite intermittent pumping of the heart

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11
Q

what are distributing arteries?

A

medium sized muscular arteries

allow selective distribution of blood to different organs in response to functional needs

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12
Q

how do medium sized arteries differ from larger arteries?

A

medium sized have prominent internal elastic lamina
fewer elastic sheaths in intima, but more prevalent smooth muscle
external elastic lamina commonly seen

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13
Q

what are resistance vessels?

A

arterioles
regulate the distribution of blood to different capillary beds by vasoconstriction and vasodilation
major determinants of systemic BP

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14
Q

discuss the smooth muscle components of arterioles

A

2-4 concentric layers in tunica media

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15
Q

discuss the structure of capillaries

A 
consist only of endothelial cells and their basement membranes
small membranes (5-10 um)
permit the passage of one RBC at a time
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16
Q

what are the 3 types of capillaries

A

continuous
fenestrated
discontinuous

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17
Q

continuous capillary

A

contain pericytes (modified smooth muscle cells) between endothelium and basement membrane

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18
Q

fenestrated capillary

A

pores or fenestrae in endothelium

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19
Q

discontinuous capillary

A

overt gaps between endothelial cells

discontinuous basal lamina

20
Q

where are continuous capillaries found

A

places where exchange between circulation and tissue is tightly regulated
skeletal muscle, brain, thymus, lungs

21
Q

where are fenestrated capillaries found

A

sites of fluid transport: intestine, kidney

22
Q

where are discontinuous capillaries found

A

liver, spleen, bone marrow

where blood cells can pass readily through

23
Q

what makes up plasma

A

90% water
10% dissolved solutes
small amt blood gases (CO2 and O2)

24
Q

what makes up dissolved solutes?

A
  1. 1% organic substances

0. 9% inorganic substances (various electrolytes)

25
Q

what makes up organic substances?

A

7.1% plasma proteins (albumin, globulin, fibrinogen)

2% other (lipids, enzymes, hormones, nutrients, waste)

26
Q

what is the function of albumin

A

most abundant plasma protein

maintains oncotic pressure

27
Q

how are large proteins that are too big for diffusion able to exit the bloodstream?

A

plasmalemmal vesicles in continuous capillaries

neutrally charged allowing for transcytosis of anionic proteins

28
Q

what is caveolin

A

a coating on transport vesicles cytoplasmic surface (caveolae)

29
Q

what are pericytes?

A

contractile cells surrounding some capillaries and post capillary venules thought to regulate blood flow
in capillaries, pericytes also allow endothelial cells to multiply and form branches (angiogenesis)

30
Q

how can pericytes lead to fibrosis?

A

in areas of chronic cell injury, they dedifferentiate into myofibroblast-like cells which overproduce ECM and lead to fibrosis

31
Q

what do fenestrae diaphragms do?

A

open and close like an optical lens to regulate permeability

without them, fenestrae are always open

32
Q

where is the preferred site of leukocyte egress from blood

A

veins

33
Q

how do leukocytes move across the vessel walls?

A

disruption of endothelial junctional complexes
migration between cells
through subendothelial basement membrane (diapedesis or extravasation)

34
Q

how do arteries and veins structure differ?

A

both have 3 tunics
distinction between media and adventitia often unclear and a distinct internal lamina is usually absent in veins
media is thinner than that found in arteries of same diameter
veins have valves to prevent reflux

35
Q

what are some critical functions of the endothelium

A

set vascular tone
vessel growth
blood clotting
inflammation

36
Q

what is prostacyclin

A

produced by endothelial cells to prevent adhesion of platelets and intravascular clot formation

37
Q

how do endothelial cells trigger coagulation?

A

release TF to stimulate the clotting cascade

38
Q

what is the result of oxidative stress on endothelium?

A

endothelial dysfunction and reduced NO bioavailability

  • leukocytes adhesion and inflammation
  • lipid deposition
  • vascular SM cell proliferation
  • vasoconstriction
  • platelet aggregation and thrombosis
39
Q

ultimate outcome of oxidative stress on vessels

A

progression of atherosclerosis and cardiovascular disease

40
Q

the formation of an atheroma

A
  1. a damage of the endothelium of an artery is followed by extracellular space infiltration of LDL in the tunica intima
  2. lipids are taken up by macrophages in the intima and fibroblasts of the subendothelial space proliferate
  3. macrophages release lipids and macrophage derived cytokines stimulate the production of collagen by proliferating SM cells
  4. ulceration of atheroma provides a surface for thrombosis
41
Q

what is the function of lymphatics

A

muscle contractions open up spaces between lymphatic endothelial cells to permit entrance of leukocytes, albumin, other proteins, and tissue fluid

42
Q

what are lymph nodes

A

distributed along lymphatic vessels to filter the lymph

sites of formation of immune responses

43
Q

Anchoring filaments

A

attach endothelial cells of lymphatic capillaries to the surrounding connective tissue to prevent lumen from collapsing

44
Q

where does interstitial fluid end up?

A

most reabsorbed into venous end of the capillary

1/10th enters the lymphatic capillaries (particularly large proteins)

45
Q

vasculogenesis vs. angiogenesis

A

vasculogenesis- creating a new vascular network
angiogenesis- sprouting from an existing network
both require VEGF, ang1, and ang2 to induce vessel formation

46
Q

how does hypoxia mediate vessel growth?

A

hypoxia causes upregulation of HIF-1 by binding to promoter elements of genes

47
Q

what does HIF-1 do?

A 
upregulate 90 target genes:
EPO
VEGF
IGF2- inhibition of apoptosis
GLUT- metabolic adaptation
-first 2 increase oxygen delivery and second 2 help with oxygen deprivation survival

RC Test 2 (17 decks)

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