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Histology > Epithelia and Glands > Flashcards

Epithelia and Glands Flashcards

1
Q

2 main characteristics of epithelial cells

A
  1. closely apposed and adhere to one another via cell-cell adhesion junctions
  2. Have polarity
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2
Q

Describe the polarity of epithelial cells

A
  1. apical domain (free surface)
  2. lateral domain (surfaces that face neighboring epithelial cells)
  3. basal domain (attached to basal lamina
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3
Q

Location/catergories of epithelium

A
  1. covering the surface of the body (skin)
  2. Exocrine and endocrine glands
  3. Lines peritoneal, pleural, and pericardial cavities (mesothelium)
  4. likes blood and lymphatic vessels (endothelium)
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4
Q

functions of epithelium

A 
*depends on location
Some Guys Are Total Poop
-protection (skin)
-secretion (glands)
-absorption (small/large intestine)
-gas exchange (lung alveoli)
-transport between blood and tissues (vascular endothelium)
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5
Q

Simple vs. Stratified epithelium

A 
simple = one layer
stratified = multiple layers
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6
Q

shape of epithelium

A

DEPENDS ON MOST APICAL SURFACE OF CELLS

squamous, cuboidal, columnar

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7
Q

Simple squamous

A

single layer and adhere closely to one another via edges
EX: meothelium (line cavities) and endothelium (vessel)
THINK: allow for diffusion

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8
Q

Simple Cuboidal

A

single row of square/low rectangular cells where the height and width of the cells are nearly the same
EX: small ducts of exocrine glands; collecting ducts in kidney`

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9
Q

Simple Columnar

A

defined rectangular outlines where the cells are taller than they are wide
- nuclei are about the same level and end to be elongated
EX: lines surface of digestive tract; founds in excretory ducts of many glands

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10
Q

stratified squamous

A
  • thick, many layers of cells with nuclei sort of aligned
  • deep cells (near basal laminar) are more cuboidal, surface cells are squamous
  • either keratinized or non-keratinized
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11
Q

Keratinized stratified squamous

A

-thickened plasma membrane and bundles of tonofilaments (keratin intermediate filaments) in cytoplasm.
-NO NUCLEUS in keratin portion
-on open (free surfaces).. exposed to world/abrasion
-provide thickness for increased protection
EX: epidermis of skin, palm of hand/feet

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12
Q

tonofilaments

A

type of keratin intermediate filament found in keratin stratified squamous cells

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13
Q

Non-keratinized stratified squamous

A

-found on inner/moist surfaces

EX: esophagus

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14
Q

stratified cuboidal

A
  • deep layers = irregular polyhedral cells that do not reach free surface
  • superficial (apical) cells = cuboidal
  • EX: ducts of sweat glands
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15
Q

stratified columnar

A
  • deep layers = irregular polyhedral cells that do not reach free surface
  • superficial (apical) cells = columnar (taller than wide)
  • EX: LARGEST ducts of exocrine glands
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16
Q

pseudostratified columnar

A
  • SIMPLE EPITHELIUM BU ALL OF THE CELLS DO NOT REACH THE FREE SURFACE
  • nuclei NOT aligned (stratified)
  • EX: goblet cell (ciliated) in respiratory system = respiratory epithelium
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17
Q

Transitional epithelium

A
  • shape of superficial (apical) cells can change depending on relaxed (contracted) or distended (stretched)
  • In relaxed (contracted): basal cells = cuboidal/columnar, apical cells = dome shaped
  • in distended (stretched): cells look squamous because the bladder is filling
  • EX ** urinary system: ureter, bladder
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18
Q

Apical domain location

A

free surface of epithelial cells; directed towards the lumen of an enclosed cavity of tube or the external environment (PART OF THE CELL THAT INTERACTS WITH THE ENVIRONMENT)

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19
Q

apical domain function

A

secretion, absorption, protection, transport of materials along the surface/into the epithelium, transduction of external stimuli via receptors

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20
Q

list the apical domain modifications

A

cilia, microvilli, sterocilia

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21
Q

lateral domain of epithelial cells: Location

A
  • facing neighboring epithelial cells

- sometimes form interdigitations to increase surface area for cell-cell interactions

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22
Q

lateral domain of epithelial cell: function

A

adhesion of neighboring epithelial cells, cell-cell communication, creation of osmotic/ionic gradient

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23
Q

Basal domain of epithelial cell: location

A
  • above the ECM

- associated with basal lamina and ECM adhesion junctions

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24
Q

Basal domain of epithelial cell: function

A

attach epithelium to the underlying CT (loose connective tissue)

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25
Q

Cilia function

A

move fluid and particles along the epithelial surface

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26
Q

cilia structure

A
  • axoneme (9+ 2 microtubules, 2 microtubules in center)

- Basal body (MTOC: 9+ 3 microtubules) anchors cilium to apical region of the epithelial cell cytoplasm

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27
Q

how is the beating movement of cilia produced?

A

movement of doublet microtubules (in axoneme) in relation to each other via dynein

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28
Q

dynein

A

protein that allows microtubule doublets to move in relation to eachother

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29
Q

structure of axoneme vs. cilia basal body vs. centrosome

A

axoneme: 9 + 2 microtubules (with dyenin on them) with 2 microtubules in center
cilia basal body: 9 + 3 microtubules
centrosome: 9 + 3 microtubules

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30
Q

where are ciliated epithelia found?

A

trachea, bronchi, and oviducts

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31
Q

common disorders due to immotile (dysfunctional) cilia

A
  • chronic respiratory problems
  • Kartagener’s syndrome (absence of dynein causes male sterility due to immotile flagella)
  • Young’s syndrome: malformation of radial spokes and dynein arms
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32
Q

Karagener’s syndrome

A

absence of dynein

causes male sterility due to immotile flagella, chronic repiratory problems

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33
Q

Young’s syndrome

A

malformation of radial spokes and dynein arms

causes chronic respiratory problems

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34
Q

Microvilli general/function/examples

A

cytoplasmic projections on the apical surface of epithelial cells

  • NOT involved in movement of particles
  • Involved in INCREASED ABSORPTION (by increasing the surface area of PM
  • EX: intestinal absorptive cells (small intestine) = striated border, kidney tubule = brush border
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35
Q

Microvilli structure

A
  • bundle of actin filaments attached at the membrane ti and extended down into the cytoplasmic terminal web
  • core of actin filaments joined by actin-crosslining proteins (villlin and fimbrin)
  • actin linked to membrane via myosin I and calmodulin
  • terminal web
  • glycocalyx (integral membrane glycoproteins)
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36
Q

terminal web of microvilli

A

contains actin, IM filaments, linking molecules; anchor into the junctional complex

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37
Q

glycocalyx of microvilli

A
  • made of integral membrane glycoproteins that interact with the external environment
  • aid in trapping or slowing external molecules close to the cell surface
  • in intestines, it contains digestive enzymes
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38
Q

Steroecilia (what, what made of, where found)

A
  • long, slender, immotile structure
  • ACTIN core (similar to microvilli)
  • found in epididymus and ductus deferns; sensory hair of inner ear
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39
Q

Stereocilia structure

A
  • cytoplasm = actin bundles anchored to terminal web
  • arise from apical protrusions at base
  • thin stereocilia are sometimes linked via cytoplasmic bridges
  • at finger-like region, actin are crosslinked by fimbrin and anchored to PM via ezrin
  • in aprical protrusions & terminal web, actin crosslinked by alpha actinin
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40
Q

cilia vs. microvilli vs. stereocilia filament composition + mobile?

A

Cilia: microtubules; motile
Microvilli: actin; motile
Sterocilia: actin; immotile

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41
Q

Junctional Complex

A
  • epthelial cell-cell adhesion junction
  • aka “terminal bar” in LM
  • 3 zones: zonula occludens, zonula adherens, macula adherens
42
Q

Zonula Occludens function

A

-impermeability to apical/outersurface; permeability to lateral cells (FORM GRADIENTS FOR TRANSPORT of water across epithelium)

43
Q

where can desmosomes be found

A

as part of junctional complex (macula adherens), or by themselves between two epithelial cells (as in keratinocytes of skin)

44
Q

Gap Junctions function

A

-communicating junction
-not just in epithelium
-facilitate the movement of ions and small regulatory molecules between cells
CHEMICAL AND ELECTRICAL COUPLING BETWEEN ADJ. CELLS

45
Q

gap junction structure

A
  • 6 connexins = pore like connexon

- connexons from 2 cells are arranged to form a cylindrical channel between the cytoplasms of 2 cells

46
Q

Pemphigus folliaceus

A

human blistering disease where autoantibodies against desmoglein I (transmembrane protein in the desomosome) causes a loss of skin cell adhesion

47
Q

What results from connexin mutations?

A
  • deafness
  • charcot-marie-tooth disease (degeneration of peripheral nerves)
  • congenital cataracts (opacity of the lens of the eye)
48
Q

Basal Lamina location/composition

A
  • specialized ECM
  • located between the basal surface of epithelial and underlying CT
  • 2 layers: lamina lucida and lamina densa
49
Q

Lamina Lucida

A

layer of BL; ELECTRON LUCID

-contains: laminin, EC cell adhesion molecules, fibronectin and laminin receptors

50
Q

Lamina Densa

A

layer of BL; ELECTRON DENSE

  • contains fibronectin and laminin (proteins), type IV collagen, heparan sulfate proteoglycans, entactin (links laminin to type IV collagen)
  • produces by epithelial cells
51
Q

Function of Basal Lamina

A
  1. structural attachment (epithel to CT)
  2. Transport barrier (must cross BL to get from epithel to CT)
  3. Filtration (in kidney)
  4. Functional polarity (epithel adhere to BL)
  5. Regeneration (scaffold for tissue regen. post wound)
    * *IN NERVE/MUSCLE SIMILAR LAYER; “EXTERNAL LAMINA”
52
Q

Basement Membrane

A

Basal Lamina + lamina reticularis

lamina lucida + lamina densa + lamina reticularis

53
Q

lamina reticularis

A

layer in basement membrane that contains type III collagen (reticular fibers) produces by underlying CT (fibroblasts)
Stains pink with Periodic Acid Schiff (PAS) base staining.. stains carbs

54
Q

what does periodic acid Schiff stain

A

PAS STAIN

stains carbohydrates and carb-rich macromolecules pink

55
Q

Hemidesmosomes location and function

A

location: basal cell layer of epithelium, prevalent in epithelia that need strong adhesion to CT
function: cell-ECM adhesion

56
Q

How do hemidesmosomes anchor?

A

link keratin IM filaments in cell to the basal lamina (lamina lucida) via anchoring filaments (laminin 5 and collagen type IV)

57
Q

Hemidesmosome associated cytoskeletal filament:

A

intermediate filaments (keratin) to intracellular attachment plaque

58
Q

Hemidesmosomes proteins

A

bullous pemphigoid antigen I (BP230) + plectin in plaque linking keratin to integrin (transmembrane linker protein)

59
Q

bullous pemphigoid

A

human blistering disease where autoantibodies against hemidesmosome components causes blisters between the basal lamina and basal surface of epithelial cells in skin, esophagus, and other tissues

60
Q

focal adhesions

A
  • structural links between actin cytoskeleton and proteins of basal lamina
  • cytoplasmic face binds actin; extracellular face w/ integrins bind to basal lamina proteins
61
Q

gland

A

a cell, group of cells, or organ that produces a secretion that is used by other cells or affects other cells
2 types: endocrine and exocrin

62
Q

Endocrine glands

A
  • prodcuts released into blood
  • NO DUCTS
  • local (does not enter blood) and systemic effects
  • products = hormones
  • in a tissue (unicellular) or multicellular
63
Q

paracrine effect

A

local endocrine secretion that does not enter to the blood

64
Q

Exocrine glands

A
  • products released through surface of epithelium

- released into a lumen connected to a DUCT (multicellular); released directly onto surface (unicellular)

65
Q

Goblet cell

A
  • a unicellular exocrine gland that secretes its product directly onto the epithelium surface (in resp. epithelium)
  • product = mucus to protect epithelial cell srufaces
66
Q

muticellular exocrine glands

A

organized secretory cells associated with a duct

67
Q

simple vs. compound gland

A

multicellular exocrine gland; dealing with the type of duct unit

simple: unbranched duct
compound: branched duct

68
Q

Tubular vs. acinar vs. mixed gland

A

multicellular exocrine gland; dealing with the type of secretory unit
tubular: secretory cells arranged in a tube
acinar: cells arranged in a rounded shape (aka alveolar)
Mixed: both tubular and rounded

69
Q 
Mucus gland
(type, product, stain)
A

EXOCRINE gland
product: thick protective lubricant (mucus) = mucin + water
Stain: pale in H&E

70
Q 
Serrous Glands
(type, product, stain)
A

EXOCRINE gland

product: protein/enzyme rich watery fluid
stain: dark with H&E

71
Q

Mixed serous/mucus glands

A

secrete both mucus and serous fluid; stain in some areas (serous) and dont in others (mucus)

72
Q

methods of exocrine secretion

A
  1. merocrine secretion
  2. apocrine secretion
  3. holocrine secretion
73
Q

merocrine secretion

A
  • release of product AT APICAL SURFACE via EXOCYTOSIS
  • most common method of secretion
    ex: apocrine glands, pancreatic acinar cells
74
Q

apocrine secretion

A
  • free, unbroken, MEMBRANE BOUND VESICLES released (contain secretory product)
  • small portion of the apical cytoplasm is released along with product
  • NOT COMMON
    ex: lactating mammary gland
75
Q

Holocrine secretion

A
  • ENTIRE cell dies and becomes part of the product
  • NOT COMMON
    ex: sebaceous glands of skin, meibomian glands of eyelid
76
Q

cilia cytoskeletal comoponent

A

axoneme (9+2) arrangement of microtubules

77
Q

microvilli cytoskeletal comoponent

A

core of actin filaments

78
Q

sterocilia cytoskeletal comoponent

A

core of actin filaments

79
Q

cilia cytoplasmic anchoring

A

basal body (9 triplet microtubules)

80
Q

microvilli cytoplasmic anchoring

A

terminal web actin crosslinked with SPECTRIN

81
Q

stereocilia cytoplasmic anchoring

A

terminal web actin crosslinked with ALPHA ACTININ

82
Q

cilia membrane linking proteins

A

N/A

83
Q

microvilli membrane linking proteins

A

myosin I and calmodulin (intestinal)

84
Q

sterocilia membrane linking proteins

A

ezrin

85
Q

microvilli: actin crosslinking proteins

A

villin and fimbrin (intestinal)

86
Q

stereocilia actin cross linking proteins

A

fimbrin

87
Q

cilia function

A

oscillation; move things along epithelial surface

88
Q

microvilli

A

increase surface area for absorption or secretion

89
Q

stereocilia

A

sensation or other function

90
Q

zonula occludens associated cytoskeletal filaments

A

actin

91
Q

zonula occludens transmembrane linker (TML) protein

A

occluden and claudin

92
Q

zonula occludens protein linking TML to cytoskeletal filament

A

ZO-1, ZO-2, ZO-3

93
Q

zonula occludens function

A

isolate lateral space from external space; concentrate solutes

94
Q

zonula adherens associated cytoskeletal filaments

A

actin

95
Q

zonula adherens transmembrane linker (TML) protein

A

cadherins (Calcium dependent)

96
Q

zonula adherens protein linking TML to cytoskeletal filament

A

cathenins

97
Q

zonula adherens function

A

cell-cell adhesion; anchor actin filaments

98
Q

macula densa associated cytoskeletal filaments

A

intermediate filaments

99
Q

macula densa transmembrane linker (TML) protein

A

desmocollins + desmogleins (a form of cadherins.. Ca2+ dependent)

100
Q

macula densa protein linking TML to cytoskeletal filament

A

desmoplakin + plakoglobin (plaque)

101
Q

macula densa function

A

cell-cell adhesion; spot welds

Histology (24 decks)

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