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IASM > IAS20 > Flashcards

IAS20 Flashcards

1
Q

developmental origin of epithelial tissue

A

originate from all 3 germ layers
ectoderm -> layer of membrane exposed to ext. env. e.g. skin epidermis
mesoderm: lining of cavities that do not open to ext. env. e.g. kidney tubules, vessel endothelium, mesothelium covering lung, abdomen, heart
endoderm: body cavity & hollow passageway: e.g. respiratory & GI tracts

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2
Q

function of epithelial tissues

A

PAESS
protection (work w/ connective tissue to act as phy barrier, stratified protect against injuries, abrasion, infection)
absorption & excretion (simple, facilitate efficient material transportation
secretion (exocrine & endocrine)
sensation (specialized sensory receptors, convey signals to nervous system e.g. retina & olfactory)

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3
Q

6 characteristics of epithelial tissue

A

exhibit functional & morpho. polarity (prominent diff. in diff. side of cells)
contains cytokeratin (inter. filament) for providing strength to resist stretching
cells close together w/ little or no IC matrix, indi. cells joined by junctional complex
sit on basement membrane
avascular -> continuous layer, obtain nutrients & remove waste from connective tissue blood vessels

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4
Q

epithelium connection w/ connective tissue, basement membrane

A

epithelial supported by connective underlying, separated by basement membrane (acellular)
stained by periodic acid-schiff, blue
basal lamina: secreted by epithelium, type IV collagen
reticular lamina: secreted by fibroblasts in connective tissue, type III collagen

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5
Q

basement membrane function

A

attachment to connective tissue
act as scaffold to guide cell migration in tissue repair

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6
Q

classification of epithelia

A

shape of apical cell: squamous (flattened), cuboidal (equal dimensions, round nucleus), columnar (tall)
no. of layers: simple / pseudostratified (1), stratified (>1), transitional (varies)

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7
Q

general functions of epithelial types in cell layer & shape

A

simple: diffusion, secretion, absorption (filtration)
stratified: protection against abrasion
squamous: diffusion (filtration)
cuboidal: secretion & absorption
columnar: highly active secretion & absorption

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8
Q

simple squamous epithelium

A

very thin, flattened
facilitate exch. of materials, absorption & secretions (maximise rate of diffusion)
e.g. tissues or cells using diffusion for molec. movement, pulmonary alveoli, lining heart, blood & lymph vessels; appendix, peritoneal & pleural cavity

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9
Q

simple cuboidal epithelium

A

contain more cytoplasm, for secretion, excretion & absorption
participate in active transport e.g. gland duct, kidney tubule

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10
Q

simple columnar epithelium

A

elongated nuclei located near base of cell
fluid transport, secretion & absorption (larger cell -> higher level of secretion & absorption than cuboidal)
e.g. intestinal lining, gallbladder

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11
Q

simple ciliated columnar epithelium

A

contain motile cilia e.g. fallopian tube

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12
Q

stratified squamous epithelium, non-keratinised

A

apical layers are living cells w/ nuclei
basal membrane generally cuboidal
for protection against desication & abrasion
e.g. uterus surface

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13
Q

stratified squamous epithelium (keratinised)

A

cell on surface subject to mech. stress when exposed to high abrasion lvl
superficial layers contain rich amts of keratin but dead
surface protection & prevent desiccation / mech. stress / abrasion
e.g. skin

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14
Q

stratified cuboidal epithelium (note: no structure)

A

for protection, secretion & limited absorption
e.g. lining of larger excretory duct of exocrine glands (salivary, sweat)

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15
Q

stratified columnar epithelium

A

basal layer cells short & irregular shaped
for protection & secretion
e.g. larynx, larger ducts of exocrine glands (mammary gland)

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16
Q

transitional epithelium

A

shape of epithelium change under diff. circumstances, only found in urinary tract (ureter, urinary bladder)
protection & accomodate high degree of stretching
bladder relaxed state: apical larger than basal, cuboidal, bulge into cavity; sig. folding of cells -> more dark purple color
stretched: apical appear squamous
upper epithelial surface fortified by plaque

17
Q

pseudostratified ciliated columnar epithelium

A

resp. system airway, resp. epithelium
cilia on apical surface, goblet cells present

18
Q

morphological polarity of epithelial cells & examples

A

distinct specializations found on diff. surfaces of epithelial cells
apical: microvilli, cilia
lateral: junctional complex (ZO, ZA, desmosome), gap junction
basement: infolding, hemidesmosome

19
Q

microvilli mechanism

A

immotile, protrude towards cavity / lumen, for absorption e.g. GI
terminal web has myosin & tropomyosin -> contract -> spreading out of actin core -> microvilli spread -> inter-microvilli space increase

20
Q

cilia structure

A

motile, facilitate fluid movement e.g. respiratory & oviduct
has organised microtubule core:
9 doublet axoneme + 2 central microtubule arrangement, each doublet has dyenin branching arm to connect to adj. doublet, interaction allows beating action
joins to basal bodies in 9 triples

21
Q

zonula occludens

A

wrap all the way around cells
proteins brings membrane close to adj. cell -> tight seal -> restrict movement of substances passing btn cells

22
Q

zonula adherens

A

wrap all the way around apical portion of cells
protein layer inside membrane attaches proteins & microfilaments of cytoskeleton
transmembrane glycoprotein: e-cadherin, interact w/ other cadherin protruded out of adj. cell to join cells; other side interact w/ terminal web
provides physical strength for cell-cell interactions

23
Q

desmosome

A

circular plaques of neighbouring cells joined together by linker proteins which interdigitate in EC space
intermediate filaments insert into each plaque, bundles across cytoplasm & anchor at desmosome at other side of cell
provides mechanical strength for cell-cell interaction, hold adj. cells together
joins all intermediate filaments of whole epithelium into one continuous network -> resist stress as pulling force evenly distributed through the layer

24
Q

gap junction

A

connexin proteins assemble into pores, join w/ pores of neighbouring cells
for communication between cells & transport of materials

25
Q

basal infolding

A

infoldings extend close to nucleus -> inc. surface area of membrane to support active transport btn epithelium & connective tissues along w/ mito present
e.g. cells involving active absorption & secretion, kidney tubules, striated ducts in salivary glands

26
Q

glandular tissue development

A

epithelial cells proliferate & grow into connective tissues OR
invaginate into connective tissues, separation by basement membrane

27
Q

endocrine vs exocrine gland formation

A

endocrine: epithelial cells separate from original epithelium & form cluster of cells, no lumen, secretions released into connective tissues -> blood
exocrine: connected to epithelium w/ lumen at center, secretory portion (simple cuboidal) secrete products into lumen -> flow to surface through a duct (inactive epithelium)

28
Q

classification by structure of exocrine glands

A

simple: straight
simple coiled: convoluted secretory portion
simple branched tubular
compound: branched
tubular: uniform tubular lumen
acinar: large bulbous collection of secretory & excretory cells, small lumen
alveolar: uniform size cells in large sac-like lumen

29
Q

goblet cell & staining

A

single cell gland
apical portion contains many secretory vessels released by exocytosis into tract, nucleus at basal side
mucus does not stain well in H&E -> paler color
forms parts of protective mucus gel layer in tracheal & intestinal epithelia

30
Q

classification by nature of secretory gland

A

mucous: flattened nuclei, secretes thick & slimy mucin; pale stain
serous: round nuclei, secretes water proteins creating eosinophilic cytoplasm in apical side; basophilic staining in basal aspect e.g. pancreas
mixed: both

31
Q

salivary demilune

A

serous cells arranged as a cap on mucous cells
both cell types associated w/ e.o., e.g. salivary gland

32
Q

mode of exocrine secretion

A

merocrine: exocytosis, no cytoplasm loss, e.g. sweat gland
apocrine: discharge of free, broken vesicles containing secretory product, e.g. mammary & lipid secretory
holocrine: cell ruptures & release secretory products e.g. sebaceous gland

IASM (16 decks)

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