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Flashcards in Epithelia and Glands Deck (101):
1

2 main characteristics of epithelial cells

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

2

Describe the polarity of epithelial cells

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

3

Location/catergories of epithelium

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)

4

functions of epithelium

*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)

5

Simple vs. Stratified epithelium

simple = one layer
stratified = multiple layers

6

shape of epithelium

DEPENDS ON MOST APICAL SURFACE OF CELLS
squamous, cuboidal, columnar

7

Simple squamous

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

8

Simple Cuboidal

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`

9

Simple Columnar

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

10

stratified squamous

-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

11

Keratinized stratified squamous

-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

12

tonofilaments

type of keratin intermediate filament found in keratin stratified squamous cells

13

Non-keratinized stratified squamous

-found on inner/moist surfaces
EX: esophagus

14

stratified cuboidal

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

15

stratified columnar

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

16

pseudostratified columnar

-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

17

Transitional epithelium

-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

18

Apical domain location

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)

19

apical domain function

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

20

list the apical domain modifications

cilia, microvilli, sterocilia

21

lateral domain of epithelial cells: Location

-facing neighboring epithelial cells
-sometimes form interdigitations to increase surface area for cell-cell interactions

22

lateral domain of epithelial cell: function

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

23

Basal domain of epithelial cell: location

-above the ECM
-associated with basal lamina and ECM adhesion junctions

24

Basal domain of epithelial cell: function

attach epithelium to the underlying CT (loose connective tissue)

25

Cilia function

move fluid and particles along the epithelial surface

26

cilia structure

-axoneme (9+ 2 microtubules, 2 microtubules in center)
-Basal body (MTOC: 9+ 3 microtubules) anchors cilium to apical region of the epithelial cell cytoplasm

27

how is the beating movement of cilia produced?

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

28

dynein

protein that allows microtubule doublets to move in relation to eachother

29

structure of axoneme vs. cilia basal body vs. centrosome

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

30

where are ciliated epithelia found?

trachea, bronchi, and oviducts

31

common disorders due to immotile (dysfunctional) cilia

-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

32

Karagener's syndrome

absence of dynein
causes male sterility due to immotile flagella, chronic repiratory problems

33

Young's syndrome

malformation of radial spokes and dynein arms
causes chronic respiratory problems

34

Microvilli general/function/examples

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

35

Microvilli structure

-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)

36

terminal web of microvilli

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

37

glycocalyx of microvilli

-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

38

Steroecilia (what, what made of, where found)

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

39

Stereocilia structure

-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

40

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

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

41

Junctional Complex

-epthelial cell-cell adhesion junction
-aka "terminal bar" in LM
-3 zones: zonula occludens, zonula adherens, macula adherens

42

Zonula Occludens function

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

43

where can desmosomes be found

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

44

Gap Junctions function

-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

gap junction structure

-6 connexins = pore like connexon
-connexons from 2 cells are arranged to form a cylindrical channel between the cytoplasms of 2 cells

46

Pemphigus folliaceus

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

47

What results from connexin mutations?

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

48

Basal Lamina location/composition

-specialized ECM
-located between the basal surface of epithelial and underlying CT
-2 layers: lamina lucida and lamina densa

49

Lamina Lucida

layer of BL; ELECTRON LUCID
-contains: laminin, EC cell adhesion molecules, fibronectin and laminin receptors

50

Lamina Densa

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

Function of Basal Lamina

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

Basement Membrane

Basal Lamina + lamina reticularis
(lamina lucida + lamina densa + lamina reticularis)

53

lamina reticularis

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

what does periodic acid Schiff stain

PAS STAIN
stains carbohydrates and carb-rich macromolecules pink

55

Hemidesmosomes location and function

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

56

How do hemidesmosomes anchor?

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

57

Hemidesmosome associated cytoskeletal filament:

intermediate filaments (keratin) to intracellular attachment plaque

58

Hemidesmosomes proteins

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

59

bullous pemphigoid

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

focal adhesions

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

61

gland

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

Endocrine glands

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

63

paracrine effect

local endocrine secretion that does not enter to the blood

64

Exocrine glands

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

65

Goblet cell

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

66

muticellular exocrine glands

organized secretory cells associated with a duct

67

simple vs. compound gland

multicellular exocrine gland; dealing with the type of duct unit
simple: unbranched duct
compound: branched duct

68

Tubular vs. acinar vs. mixed gland

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

Mucus gland
(type, product, stain)

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

70

Serrous Glands
(type, product, stain)

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

71

Mixed serous/mucus glands

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

72

methods of exocrine secretion

1. merocrine secretion
2. apocrine secretion
3. holocrine secretion

73

merocrine secretion

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

74

apocrine secretion

-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

Holocrine secretion

-ENTIRE cell dies and becomes part of the product
-NOT COMMON
ex: sebaceous glands of skin, meibomian glands of eyelid

76

cilia cytoskeletal comoponent

axoneme (9+2) arrangement of microtubules

77

microvilli cytoskeletal comoponent

core of actin filaments

78

sterocilia cytoskeletal comoponent

core of actin filaments

79

cilia cytoplasmic anchoring

basal body (9 triplet microtubules)

80

microvilli cytoplasmic anchoring

terminal web actin crosslinked with SPECTRIN

81

stereocilia cytoplasmic anchoring

terminal web actin crosslinked with ALPHA ACTININ

82

cilia membrane linking proteins

N/A

83

microvilli membrane linking proteins

myosin I and calmodulin (intestinal)

84

sterocilia membrane linking proteins

ezrin

85

microvilli: actin crosslinking proteins

villin and fimbrin (intestinal)

86

stereocilia actin cross linking proteins

fimbrin

87

cilia function

oscillation; move things along epithelial surface

88

microvilli

increase surface area for absorption or secretion

89

stereocilia

sensation or other function

90

zonula occludens associated cytoskeletal filaments

actin

91

zonula occludens transmembrane linker (TML) protein

occluden and claudin

92

zonula occludens protein linking TML to cytoskeletal filament

ZO-1, ZO-2, ZO-3

93

zonula occludens function

isolate lateral space from external space; concentrate solutes

94

zonula adherens associated cytoskeletal filaments

actin

95

zonula adherens transmembrane linker (TML) protein

cadherins (Calcium dependent)

96

zonula adherens protein linking TML to cytoskeletal filament

cathenins

97

zonula adherens function

cell-cell adhesion; anchor actin filaments

98

macula densa associated cytoskeletal filaments

intermediate filaments

99

macula densa transmembrane linker (TML) protein

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

100

macula densa protein linking TML to cytoskeletal filament

desmoplakin + plakoglobin (plaque)

101

macula densa function

cell-cell adhesion; spot welds