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Epithelial > week 19 structure of epithelium > Flashcards

week 19 structure of epithelium Flashcards

1
Q

what domains are cells made up of that are polarised (orientated) the same way throughout the epithelial sheet

A

apical and basolateral

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2
Q

cells sit next to eachother and attach to a thin, fibrous_____

A

basement membrane

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3
Q

epithelia line the surfaces of ____-

A

cavities and structures

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4
Q

epithelial sheets lack

A

blood vessels

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5
Q

epithelial sheets can contain nerves that allow what

A

neural contribution to sensation, absorption, protection and secretion

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6
Q

in development, epithelia act in conjunction with what other tissue type

A

mesenchyme

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7
Q

in development, epithelia act in conjunction with mesenchyme (another tissue type) to form what

A

nearly every organ in the body

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8
Q

if a cell is cuboidal what does this mean

A

cube shaped

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9
Q

if a cell is columnar what does this mean

A

rectangular

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10
Q

if a cell is squamous what does this mean

A

flat

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11
Q

if a cell is simple epithelium what does this mean

A

single layer

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12
Q

if a cell is stratisfied epithelium what does this mean

A

several layers

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13
Q

if a cell is pseudo-stratified epithelium what does this mean

A

one cell, layers of varying heights

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14
Q

if a cell is ciliated what does this mean

A

primary cilia and motile cilia

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15
Q

if a cell is described with neural connections what does this mean

A

form sn eural connections

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16
Q

if a cell is described as mucus secreting what does this mean

A

gobelt cells

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17
Q

for example, if a cell was described as pseudo-stratified ciliated columnar epithelium, what does this mean

A

cells of varying height but all with single attached to basement membrane

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18
Q

in lung neuroepithelial bodies what are the epithelial functions

A

chemosensing and regulation of breathing

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19
Q

in kiney nephrons and collecting duct what are the epithelial functions

A

ion transport]fluid homeostasis
hormone secretion
acid base balance

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20
Q

in the gut mucosa, how is the cell epithelium described (structure)

A

simple columnar epithelium with goblet cells

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21
Q

what is the epithelial function of the gut mucosa

A

ion transport
fluid homeostasis
mucus and digestive enzyme secretion
nutrition absorption

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22
Q

how is the epithelium structure of the blood brain barrier described

A

endothelial interaction with astrocytes

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23
Q

what is the blood brain barrier’s endothelium astrocyte interactions

A

ion transport
fluid homeostasis
selective hormone signaling

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24
Q

why is polarity crucial for function

A

gives direction to the transport of ions and nutrients
specialisation of funtion at one end of cell
supprt formation of complex architectural shapes

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25
Q

loss of polarity is key to _____

A

disease

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26
Q

microvilli gives the apical membrane of the cell increased ______ to increase interactions with external environment

A

surface area

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27
Q

how mnany layers are there in the epithelial cell junctions

A

5

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28
Q

what are the 5 layers in the epithelial cell junctions

A

adherens junction
tight junctions
desmosome junction
gap junction
hemidesmosome junction
A
T
D
G
H

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29
Q

what are cadherins (in adherens junction)

A

cell adhesion proteins

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30
Q

what are cadherins fundamental for

A

multicellular (metazoan life)

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31
Q

Ca2+ - dependant homodimerizations between extracellular domains does what

A

holds cells in contact

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32
Q

carboxy terminus is anchor for what 4 things

A

p120
alpha
beta
gamma (catenin)

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33
Q

p120 is a what

A

prototypical catenin isoform

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34
Q

what does p120 do

A

stabalise adherens junctions and initiates formation of other junction complexes

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35
Q

alpha-catenin forms what

A

a homodimer

36
Q

alpha-catenin forms a homodimer that anchors what

A

actin filaments to the membrane

37
Q

beta-catenin is released from _____ by _______

A

E-cadherin by proteolysis

38
Q

beta-cadherin is releaased from £-cadherin by proteolysis and acts as a what

A

nuclear signal to stimulate loss of polarity and cell growth

39
Q

gamma-cadherin (plakoglobin) does what to junction complexes

A

alters junction complexes

40
Q

gamma-cadherin alters typ of junction complexes and is common to what

A

desmosomes

41
Q

F actin forms supporting ____ structure around what

A

belt
inner cell membrane

42
Q

if adherens junction disrupted ____ Catenin move to nucleus and does what

A

beta
promotes cell growth and loss of polarity (cancer)

43
Q

Junction complexes stabilise what

A

cell structure and inhibit cell passage

44
Q

junction complexes stabilise cell structure and inhibit cell cycle passage by -

A

sequestering key transcription factors

45
Q

what type of tight junctions form the apical side of adherens junction and creates an impermeable barrier that blocks intracellular movement of molecules between cells and acts as a fence to separate the apical and basolateral membranes

A

zona occludens

46
Q

basic unit of tight junction is what

A

occluden

47
Q

homedimerization of occluden extracellular domains forms what

A

impermeable seal between cells

48
Q

ransmembrane occluden domains seperate what

A

apical and basolateral membranes

49
Q

transmembrane occludens domains seperate apical and basolateral domains, what does this prevent

A

prevents movement of proteins between these membranes

50
Q

zona occludens proteins anchor what

A

cytoskeltal proteins (actin and tubulin) to the tight junction complex

51
Q

microvilli are supported by actin anchored to where

A

actin ring

52
Q

phosphoinositide-3kinase (PI3K) and its inhibter (PTEN) regulate what

A

phosphoinotiside (Ptdlns) content of apical and basolateral membranes

53
Q

Par3 recruits PTEN to where

A

tight junction

54
Q

PTEN enriches what and where

A

PIP2 in apical membrane

55
Q

PI3K localises to where

A

adherens junctions

56
Q

PI3K enriches PIP3 to where

A

Basolateral membrane

57
Q

____ form loose junctions between cells enabling cell shape to distort without tearing during mechanical stress

A

desmosomes

58
Q

desmosomes form what

A

loose junctions between cells enabling cell shape to distort without tearing due to mechanical stress

59
Q

where are desmosomes most commonly expressed

A

cells exposed to stretch and shear (lower airway of lung)

60
Q

what are desmosomal junctions composed of

A

cadherin family proteins
desmoglein
desmocollin

61
Q

desmoglein and desmocollin are anchored in the membrane by what

A

plakoglobin and plakophillin heterodimers

62
Q

desmoplakin binds desmin and cytoskeltal protein to where

A

desmosome junction complex

63
Q

desmoplakin binds what to proteins to the desmosome junction complex

A

desmin and cytoskeletal protein

64
Q

gap junctions are formed from what

A

hexamers of connexin proteins

65
Q

gap junctions function as what

A

channels that connect the cytoplasm of one cell to another

66
Q

gap junctions are channels that connect the cytoplasm of one cell to another so that they establish what

A

planar cell polarity (PCP)

67
Q

how many connexins form a hemi channel

A

6

68
Q

extracellular connexin loops link hemi channels between ____

A

neighbouring cells

69
Q

channel pore facilitates electric and metabolic coupling between what

A

cells

70
Q

channel pore facilitates ____ and _____ coupling between cells

A

electric and metabolic

71
Q

what are the major components of the basement membrane (hemidesmosome)

A

laminin
integrins
collagens
fibronectin
nidogen
perlecan

72
Q

what is the role of laminin in the hemidesmosome

A

primary organiser of the BM proteins and froms the lamina densa

73
Q

what is the role of integrins in the hemidesmosome

A

expressed on basolateral side of cell and form lamina lucida - binds to lamina

74
Q

what is the role of collagens and fibronectin in the hemidesmosome

A

chicken wire like meshwork that gives BM tensile strength

75
Q

what is the role of nidogen and perlecan in the hemidesmosome

A

link leminin to collagen and fibronectin

76
Q

mutations that cause cancer can disrupt the association of PTEN with what and where

A

Par3 at tight junctions

77
Q

loss of PIP2/PIP3 signature of apical and basolateral membranes disrupts what
(2)

A

intracellular trafficking and polarity

78
Q

degradation of E cadherin releases what

A

Beta-catenin

79
Q

degradation of E-cadherin releases Beta-catenin which enters where and increases what

A

the nucleus and increases cell growth by activating LEF-1/TCF driven expression of cell cycle genes

80
Q

activation of an autoimmune response which disrupts ________ enhancing pathological paracellular support

A

tight junction barrier

81
Q

gluten in diet stimulates _____ secretion from where

A

zonulin
gut epithelium

82
Q

gluten in diet stimulates zonulin secretion from gut epithelium which opens

A

tight junctions

83
Q

gluten enters the blood stream and promotes what

A

an autoimmune response which degrades the gut epithelial barrier and further exacerbates immune response

84
Q

gluten enters the blood stream and promotes an autoimmune response which degrades the gut epithelial barrier and further exacerbates immune response by

A

augmenting T cell recruitment

85
Q

in ehlaors danlos what causes the mutation

A

collagen

86
Q

in EDS the mutation in collagen genes disrupts epithelial adhesions to the basement membrane resulting in what

A

hyper flexible joints and loss of cell polarity

Epithelial (12 decks)

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