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Histology > Block 1: Epithelium > Flashcards

Block 1: Epithelium Flashcards

1
Q

Epithelium:

Location
F(x):

A

location: lining all external and internal surfaces of the body
f(x): protecting surface (ex: epidermis); absorption (ex: intestinal lining); secretion (ex: parenchymal cells of glands); transport of material @ surface (moderated by cilia); excretion (kidney tubules); gas exchange (lung alveoli); gliding b/w surfaces (mesothelium(

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2
Q

Are epithelial cells vascular or avascular?

A

avascular. nutrients are delivered by diffusion

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3
Q

What are the domains of epithelia?

A

apical domain
lateral (junctional complexes)
basal (basement membrane)

functional domains: apical, basolateral

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4
Q

How are adjacent cells held together @ their cell membranes and to tissues beneath?

A

the basement membrane lies at the interface b/w epithelial cells and connective tissue

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5
Q

Lamina Propria

A

CT (loose CT) that underlines epithelia lining organs of digestive, respiratory and urinary systems

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6
Q

Describe polarity of epithelial cells

A

epithelial cells show polarity, with organelles and membrane proteins distributed unevenly

basal pole: cell region contacting ECM & CT’s
apical pole: cell region facing a space (where you’ll find cilia, microvilli, etc)

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7
Q

Desmosome
f(x)
result of issues

A

f(x): form strong attachment points that supplement tight junctions to maintain epithelial integrity

issue: reduced cohesion of epidermal cells

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8
Q

Hemidesmosome
f(x)
result of issues

A

f(x): bind epithelial cells to underlying basal lamina

issue: epidermolysis bullosa, a skin blistering disorder

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9
Q

Why is polarity of epithelial cells necessary?

A

some cells have a unique apical surface specialization that increases the apical surface area for better absorption or to move substances along the epithelial surface

ex: microvilli, stereocilia, cilia

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10
Q

What is the apical domains specialization?

A

microvilli, stereocilia, cilia

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11
Q

Microvilli
f(x)
morphology

A

f(x): prominent in epithelia specialized for absorption

morphology: usually uniform in length, visible as a brush border projecting into the lumen

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12
Q

Stereocilia
f(x)
morphology

A

f(x): prominent on absorptive epithelial cells lining hthe male reproductive system
morphology: longer and much less motile than microvilli; often having distal branching

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13
Q

Cilia
f(x)
s(x)

A

f(x): highly motile apical structures; rapid beating can move a current of fluid along the epithelium
s(x): 9+2 arrangement of microtubules, called an axenome, with successive changes that can produce ciliary movement

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14
Q

Tight Junctions
proteins
major cytoskeletal component
f(x)

A

occludins, claudins, ZO proteins
cytoskeletal component: actin filaments
f(x): barrier; control the passage of substances between adjacent cells

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15
Q

Adherens Junctions
cytoskeletal component
proteins
f(x)

A

proteins: E-cadherin, catenin
cytoskeletal component: actin filaments
f(x): anchoring junction to support tight junctions

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16
Q

Desmosomes
proteins
cytoskeletal component
f(x)

A

protein: cadherin family proteins (desmogleins, desmocollin)
cytoskeletal component: intermediate filament
f(x): strong point of intermediate filament b/w adjacent cells, strengthening the tissue

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17
Q

Hemidesmosome
proteins
cytoskeletal components
f(x)

A

proteins: integrins
cytoskeletal components: intermediate filaments
f(x): anchors cytoskeleton to basal lamina

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18
Q

Which domain is associated w/ a glycocalyx coat

A

microvilli
there’s a thick glycocalyx covering microvilli of the intestinal brush border, containing membrane bound proteins and enzymes for macromolecule digestion

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19
Q

Gap Junctions
proteins
f(x)

A

proteins: connexins

f(x): allow for cell to cell communication

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20
Q

Describe the parts of the basement membrane

A

basal lamina: contains laminin, fibronectin
reticular lamina: contains type III collagen (reticular fibers)

the components of these 2 laminae are glycoproteins. they are PAS positive.

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21
Q

In malabsorption, what happens to the apical domain of the epithelial cells lining the internal surface of the small intestine?

A

one of the first pathological changes is loss of the microvilli brush border of the absorptive cells

celiac disease

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22
Q

How are the identities of apical and basal surfaces of epithelia maintained?

A

tight junctions act as a belt around the cell to prevent proteins from moving from the apical to basolateral surfaces of the membrane

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23
Q

What happens if your tight junctions aren’t stable?

A

you’ll have less fusion, which leads to a “leaky” epithelium

24
Q

What happens if there is an abnormal immune response to desmosmes?

A

bullous pemphigoid and pemphigus vulgaris

25
Q

In what tissues would you expect to find a large number of gap junctions?

A

abundant in epithelia, nervous, and cardiac tissue. anything that beats rhythmically will have gap junctions.

26
Q

Simple Squamous Epithelium
location
f(x)
how form meets f(x):

A

lining of blood vessels (endothelium); lining of body cavities (mesothelium); bowman’s capsule in Kidney; lining of respiratory spaces (alveoli) in the lungs

F(x): gas exchange, nutrients; barrier, lubrication

form meets f(x): thinness reflects primary function in rapid exchange of substances b/w

27
Q

Simple Cuboidal Epithelium
F(x)
Location

A

F(x): absorption and secretion; protection

location: small ducts of exocrine glands; surface of ovary; kidney tubules; thyroid follicles

28
Q

Simple Columnar Epithelium
F(x)
Location

A

f(x): absorption and secretion; protection; lubrication

location: lining GI system, gallbladder, some large ducts

29
Q

What would you expect to find in a stratified epithelium that has a genetically defective protein in the hemidesmosomes and desmosomes?

A

desmosomes: blistering diseases
hemidesmosome: since hemidesmosomes anchor the basal lamina to the epidermis, defective proteins would lead to separations b/w epidermis and basal lamina, leading to subepidermal blistering

30
Q

Stratified Squamous Epithelium

f(x)
location

A

f(x): protection, secretion

location: lining oral cavity, esophagus and vagina

31
Q

Stratified Cuboidal

f(x)
location

A

F(x): absorption and secretion

location: sweat glands and ducts, larger ducts of exocrine glands

32
Q

Stratified Epithelium
f(x)
location

A

f(x); secretion, absorption, protection

location: largest ducts of exocrine glands

33
Q

Pseudostratified Epithelium

appearance
f(x)
location

A

appearance: appears stratified, composed of only 1 layer though. all cells tough basement membrane, not all reach luminal surface. typically have cilia on apical surface

f(x): protefction, secretion, absorption, lubrication
location: lining trachea, bronchi, nasal cavity, ductus deferens

34
Q

Describe the structure of the basal lamina

A

basal lamina is sheet like, formed by type IV collagen and lamins

35
Q

Basement Membrane
s(x)
f(x)

A

s(x): formed by fusion of basal lamina and reticular lamina

f(x): semipermeable filter for substances reaching epithelial cells from below

36
Q

Transitional Epithelium

location
f9x)

A

stratified epithelium found exclusively in bladder, urethra, ureters, etc.

able to distend; top layer changes shape based on distension of underlying tissue

37
Q

Pemphigus Vulgaris
what happens?
result

A

what: body produces abnormal antibodies to the proteins forming desmosome junctions in the skin, preventing normal desmosome adhesion
result: widespread skin and mucous membrane blistering

38
Q

Bullous Pemphigoid
what happens
result

A

what: blistering disease caused by formation and direction of antibodies against proteins in hemidesmosomes
result: subepidermal blisters since hemidesmosomes anchors the epidermis to basal lamina

39
Q

Why is the basement membrane necessary?

A

the basement membrane, a sheet of macromolecules, serves as an impermeable filter for substances reaching epithelial cells from below

40
Q

Epidermolysis Bullosa

A

deals with the basement membrane

41
Q

Goodpasture’s Syndrome

A

antibodies directed against type IV collagen located in the basement membrane of lungs and kidneys

42
Q

Gland
what is it?
f(x)

A

what: epithelial cells

f(x): produce and secrete various macromolecules

43
Q

Why do epithelia form glands?

A

glands develop into covering epithelia in the fetus by proliferation and growth into the underlying CT, followed by further differentiation

44
Q

Exocrine Glands

A

remain connected with surface epithelium, forming tubular ducts lined w/ epithelium that deliver secreted material where its used

45
Q

Endocrine Glands
s(x):
f(x):

A

s(x): lose the connection to their original epithelium, lacking ducts
f(x): closely assoicated w/ capillaries and release hormones that are specific for target organs and tissues

46
Q

Merocrine Secretion

A

materials are secreted via exocytosis from membrane bound vesicles or secretory granules

47
Q

Holocrine Secretion

A

the cell is completely disrupted as it releases the product, and cell debris, into the lumen

ex: sebaceous glands

48
Q

Apocrine Secretion

A

product accumulates at the apical ends of cells, and the apical portion along with the product are secreted

49
Q

Myoepithelial Cells

A

found on the basal lamina and wrap around the secretory of the gland; these cells contract to squeeze out the contents

50
Q

Why is the sweat produced by the glands of CF patients full of chloride?

A

sweat in CF patients is salty b/c these patients have defects in a transmembrane conductance regulator (CFTR) of epithelial cells that leads to disruptive accumulations of thick mucus in the respiratory and digestive tracts

51
Q

Differentiate b/w the different secretory products

A

mucous: polysaccharides added to a protein substrate to produce mucin, which is packaged into a secretory granule that becomes hydrated when released from the cell to form mucous
serous: proteins packed into secretory granules and released by exocytosis

52
Q

Goblet Cell

A

unicellular exocrine glands

53
Q

What parts of the body are not covered by epithelium

A

articular cartilage
tooth enamel
anterior portion of iris

54
Q

Basal Interdigitations
s(x)
f(x)

A

s(x): deep infoldings of the basal membrane that partition the cytoplasm into alcoves
f(x): alcoves contain many mitochondria and increase the surface area for extracellular osmotic gradient

55
Q

Basal lamina contains what type of collagens

A

type IV

Histology (6 decks)

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