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Histology Exam 1 > Epithelial Tissue > Flashcards

Epithelial Tissue Flashcards

1
Q

What is epithelia? What does it cover? What is it derived from?

A

epithelial cells are characterized by production of keratin intermediate filaments

covers body surfaces, lines body cavity, and forms glands

derived from ecto, endo, and mesoderm

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2
Q

What does ectoderm give rise to?

A

epidermis, oral and anal mucosa
cornea and lens epithelia of eye
enamel organ and enamel of teeth
anterior pituitary
inner ear

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3
Q

What does neuroectoderm give rise to?

A

neural tube (CNS)
pineal body, posterior pituitary
sensory epithelium of eye, ear and nose
neural crest (PNS)
ganglia, nerves, glial cells, adrenal medulla, melanocytes, neuroendocrine cells

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4
Q

What does mesoderm give rise to?

A

epithelium of kidneys and gonads
mesothelium
endothelium
adrenal cortex

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5
Q

What does endoderm give rise to?

A

respiratory epithelium
almentary epithelium
liver, pancreas, gallbladder, thyroid, parathyroid, and thymus
epithelial lining of tympanic cavity
transitional epithelium of bladder

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6
Q

What are epithelial functions?

A

barrier (skin), SPM, secretion, absorption, transport, sensation

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7
Q

Characteristics of epithelia

A

avascula - never penetrated by blood vessels
supported by basement membrane, separates epithelium from underlying connective tissue and blood vessels
cells of epithelium rely on diffusion of O2 and nutrients from underlying tissue

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8
Q

What are mucous membrane?

A

aka mucosa
epithelium that lines cavities that connect with outside world (alimentary, respiratory, and urogential tracts)

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9
Q

What do mucous membranes contain?

A

contains surfacve epithelium of ectoderm (or endoderm), basement membrane, supporting connective tissue, and sometimes layers of smooth muscles

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10
Q

What are serous membrane?

A

epithelium that lines closed body cavities (pleural or pericardial cavities)

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11
Q

What do serous membranes consist of?

A

epithelial lining, the mesothelium (mesodermally derived), basement membrane, and supporting connective tissue

lack mucularis mucosa

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12
Q

What is endothelium?

A

epithelium that lines blood and lymph vessels (mesodermally derived)

associated with variable numbers of muscles and connective tissue layers, or tunics

most epithelial cells have finite lifespan

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13
Q

What are extrenal lamina? Another name for them?

A

extracellular martix proteins
basement membrane

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14
Q

Where are epithelial cells attached?

A

basal surface of epithelial cells attach to underlying basement membrane

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15
Q

What do basement membranes provide?

A

structural support, scaffolding for growth, differentiation, and migration of cells during embryonic growth and regeneration

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16
Q

What is a basement membrane made up of? What does it do?

A

non-cellular protein and polysaccharide-rich layer, acts as filter between epithelium and underlying connective tissue

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17
Q

What do basement membranes do for kidneys?

A

glomerular basement memberane acts as highly elective filter for urine formation

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18
Q

What are the major components of basement membranes?

A

GAG’s, Type 4 collagen, and structural glycoproteins (laminin, fibronectiin, and entactin)

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19
Q

On an EM, basement membranes have electron dense layers called

A

lamina densa which is sandwiched between lamina lucida and lamina reticularis

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20
Q

What is lamina lucida?

A

10-50nm in diameter, in contact with basal cell membrane

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21
Q

What is lamina reticularis?

A

20-30um in diameter, merges with surrounding tissue

22
Q

What is lamina densa anchored to?

A

underlying connective tissue by microgibrils of type 4 collagen (anchoring filaments)

23
Q

What are cell junctions? What do the do/allow for? What are the three types?

A

intercellular epithelial attachment sites
epithelial cells adhere to one another via cell junctions
allow for communication between cells
Types: Occluding, adhering, and communicating

24
Q

What are occluding junctions? Where are they located? What are the two types?

A

tight junctions
located immediately beneath luminal surface of simple columnar epithelia
types: zonula occludens and fascia occludens

25
Q

What do gaskets do? What kind of junction acts like a gasket?

A

prevent leakage between cells
occluding junctions

26
Q

What are zonula occludens?

A

portions of opposing cell membranes fuse together, forming continuous, circumferential band around a cell

27
Q

What are fascia occludens?

A

present between endothelial cells in wall of blood vessels (specialized tight junction)

28
Q

What are adhering junctions? What do they do?

A

anchoring junctions
bind cells together, act as anchoring points for cell cytoskeleton

29
Q

What are zonula adherens?

A

a continous band characterized by transmembrane glycoproteins called cadherins

30
Q

What are macula adherens? Where are they located? What are they associated with?

A

desmosomes
small circular patches; most common type of cell junction
on lateral surface of cell
associated with attachment proteins, including desmoplakins, desmogleins, and monofilaments

31
Q

What are hemidesmosomes? Where are they located? What are they associated with?

A

half desmosomes
found on basal surface of cell only, anchoring it to basement membrane via integrins (transmembrane receptor proteins)
associated with high mechanical abrasion/shearing forces (skin)

32
Q

What is a junctional complex? What are the three zones?

A

terminal bar
specialized, circumferential, intercellular connection
hybrid between adhering and occluding junctions - forms diffusion barrier between cells

zones: zonula occludens (tight), zonula adherens (adherent), and macula adherens (desmosomes)

33
Q

What are communicating junctions? Where are they located? What do they allow?

A

gap junctions or nexus junctions
focal, or regional adherent xones located on lateral border of cell
roughly circular, intercellular contact areas containing hundreds of individual channels called connexons formed by connexions

permit passage of small molecules between adjacent cells, allow transport of information and metabolites between cells

34
Q

What are microvilli? What do they do? What do they contain? What are they supported by?

A

finger-like cytoplasmic projections that extend from cell surface
increase surface area for absorption or secretion = striated border in intestine and brush border in renal tubules

contain actin filaments
supported by terminal web, network of actin microfilaments at base of microvillli, provide support

35
Q

What are stereocilia?

A

long microvilli, not cilia, found only in epididymis of males and sensory cells of inner ear

non-motile, also contain actin filaments

36
Q

What are cilia?

A

long, motile cytoplasmic extensions
possess axoneme arrangment of microtubules
each cilium arises from individual basal body
cilia beat in synchronous metachronal rhythm - has rapid, rigid, effective stroke and slower, flexible recovery stroke

37
Q

What is kartagener’s syndrome?

A

causes sterility in makes due to non-functional flagella on sperm

38
Q

What is dextrocardia? or situs inversus?

A

heart is on right side
due to absence of ciliary activity during embryonic development

39
Q

What is hydrocephalus?

A

due to non-functional cilia on ependymal cells unable to circulate CSF
insufficient drainage or large secretion of CSF

40
Q

What is the epithelial classification?

A

three criteria: # of cell layers, shape of cells, surface specialization (ex: ciliated)

41
Q

What are the number of cell layers?

A

simple - 1 cell layer thick
stratified - 2 or more cell layers
pseudostratified - looks stratified, but isn’t (all cells rest on basement membrane, but not all cells extend to epithelial surface

42
Q

What are the shapes of cells?

A

squamous (flattened width > height)
cubodial (width = depth = height)
columnar (height > width)

all at the surface of epithelium, not base

43
Q

What is transitional epithelium?

A

lines most of urinary tract
stratified epithelium
modified for distensibility
varies from squamous to cuboidal

44
Q

What is endothelium?

A

epithelium lining blood vessels and lymphatics; simple squamous

45
Q

What is mesothelium?

A

epithelium lining closed body cavities
simple squamous

46
Q

What types of glands are there?

A

simple gland: unbranched ducts
compound gland: branched ducts

47
Q

What are the shapes of glands?

A

tubular: tube-like
acing: alveolar - sac-like or flask-shaped individual sacs called acinus
tubuloacinar: alveolar - intermediate tube with dilated end

48
Q

What types of secretory product comes from glands?

A

serous: watery, basophilic acini (stain purple, blue)
mucous: thick, viscid secretion (stain clear on H&E)
mixed: seromucous - contain both mucous and serous acini, often include serous demilunes
seabecous: secrete lipids in form of sebum
ceruminous: in external ear canal - secrete cerumen (ear wax)

49
Q

What are the two major functional groups of glands?

A

endocrine gland: lack ducts, secrete products directly into bloodstream

exocrine gland: secrete product onto epithelial surface via ducts
contain myoepithelial cells
lie betwen secretory cells and basement membrane - assist in secretion
example: goblet cell - secrete mucous

50
Q

What is the mode of discharge for a gland?

A

merocrine: eccrine = only secretory product released
most common, involves simple exocytosis (ex: proteins)

apocrine: secrete membrane-bound vesicles; product accompanied by some cytoplasm (ex: lipids)

holocrine: entire cell secreted - sebaceous glands

Histology Exam 1 (6 decks)

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