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Histology and Embryology > Epithelium Lecture > Flashcards

Epithelium Lecture Flashcards

1
Q

What are the characteristics of epithelial cells?

A 
Avascular 
Covers exterior body 
Lines internal cavities
Forms secretory portion of glands
Receptors for special senses
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2
Q

Does a basement membrane have cells?

A

Acellular

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3
Q

How does gas exchange happen at the basement membrane?

A

Diffusion

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4
Q

What are the domains of the epithelium cells?

A

Apical -> lumen/environment
Lateral-> neighbor cells and junctional complexes
Basal domain-> basement membrane

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5
Q

What is simple squamous epithlium? Where is it found?

A

Single layer polygonal cells
Thinnest tissue of body

-Bowman’s capsule kidney, respiratory spaces in lungs

LINES blood + lymphatic vessels for DIFFUSION

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6
Q

What is lining all blood + lymphatic vessels?

A

Simple squamous epithlium

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7
Q

What lines the atria + ventricles of the heart

A

Endocardium -> Simple squamous epithelium

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8
Q

What lines the walls + closed cavities of the body

A

Mesothelium -> simple squamous epithelium

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9
Q

What tissue forms ducts and glands?

A

Simple cuboidal epithelium

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10
Q

What are the characteristics of simple cuboidal epithelium?

A

Width similar to height

Nuclei are at similar levels, and nuclei is not much taller than cell

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11
Q

Where do you find simple cuboidal epithelium?

A

Kidney tubules, small ducts of exocrine

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12
Q

Do exocrine or endocrine glands have ducts?

A

Exocrine glands have ducts, endocrine glands do not

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13
Q

What are the characteristics of simple columnar epithelium?

A

Nuclei are lined up at basal portion of the cell

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14
Q

Where do you find simple columnar epithelium?

A

Small intestine, stomach lineing

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15
Q

What kind of epithelium has brush border? What is the brush border called?

A

Simple columnar epithelium, microvilli

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16
Q

What epithelium has goblet cells? What do they do?

A

Simple columnar epithelium, unicellular gland which secretes mucus

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17
Q

In stratified epithelium, what is the shape based off of?

A

The top most layer

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18
Q

What kind of epithelium are found in the esophagus, oral canal and the vagina?

A

Stratified Nonkeratinized epithelium

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19
Q

Where is stratified squamous epithelium kertanized found?

A

SKin

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20
Q

What happens when stratified squamous epithelium becomes keratinized?

A

lost nuclei, peel off

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21
Q

What epithelium is found in sweat glands/ large ducts of exocrine glands?

A

Stratified cuboidal epithelium

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22
Q

Where is stratified columnar epithelium found?

A

Largest ducts of exocrine, rectum, anus

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23
Q

Keratinization is only applicable to what type of epithelium?

A

Stratified squamous

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24
Q

Where is pseuostratified columnar epithelium found?

A

Trachea

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25
Q

What is a characteristic of pseudo stratified epithelium?

A

All cells touch the base, only some reach the surface

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26
Q

What is transitional epithelium?

A

Specialized stratified epithelium *cobblestone

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27
Q

Where is transitional epithelium found?

A

Bladder, ureter, urethra

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28
Q

What are characteristics of transitional epithelium?

A

Impermeable to salts + water, plasma membrane hugely folded to stretch

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29
Q

What are exocrine glands? What are endocrine glands?

A

Exocrine secrete into ducts

Endocrine secrete into nearby capillaries

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30
Q

What are merocrine secretion?

A

Exocrine

Vesicle approches apical domain -> fuses with plasma membrane into extracellular space

Plasma membrane can be returned via endocytosis and recycled

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31
Q

What is apocrine secretion?

A

Exocrine

(milk)
Apical cytoplasm is pinched off w/ secretions

Mammary glands secrete LIPIDS by APOCRINE and milk casein by MEROCRINE

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32
Q

What is holocrine secretion?

A

Accumulates secretory product (sebum) and then disintegrates

33
Q

Why are epithelium cells polarized?

A

For function and junction

TIGHT JUNCTIONS ENSURE POLARITY

34
Q

What are microvilli?

A

Closely packed “brush border” present in kidneys + intestine

35
Q

What covers microvilli?

A

Glycocalyx coat of glycoprotein

36
Q

What is within microvilli?

A

A core of actin filaments which are cross linked by actin binding proteins

37
Q

What do actin filaments connect to within microvilli?

A

Actin filaments extend downward to cytoplasm where they attach to terminal web (horizontal actin filaments below base)

38
Q

What is significant about stereocilia?

A

Non-motile (one cilium)
Faciliate absorption
Mechanical vibration (ear)

39
Q

Are cilia motile? Where are they found

A

Cilia are motile (fluid over epithelial surface) -> can actively propel particles along a cell surface

Found in respiratory tract

40
Q

What are the characteristics of cilia?

A

Beat in synchronous pattern, arranged in orderly rows (respiratory tract) looks like hair at apical surface

Basal bodies are thin, dark staining at base

41
Q

What is a motile cilia composed of?

A

Microtubules in 9+2 pattern w/ doublet dynein arms

Radial spokes extend from outer doublets to center

Basal body has a core of 9 MT triplets, assembly INITIATED BY BASAL BODY

42
Q

What is Kartagener’s syndrome?

A

Structural abnormalities that results in ABSENCE of dyeing arms -> dysfunctional cilia -> bronchitis

INFERTILITY in males/females bc motor proteins damaged

43
Q

What are mono-cilia?

A

Non-motile primary cilia such as chemosensory, osmosensors, mechanosensors

ESSENTIAL IN GASTRULATION (right left symmetry

44
Q

What do junctional complexes between cells generate?

A

A functional barrier that maintains the cohesive nature of the epithelium

-structure + polarity

45
Q

What are junctional complexes made up of?

A

cell adhesion molecules (CAMs)

46
Q

What are lateral specializations?

A 
Zona occludens (tight junction)
Zona adherens (adhesion belt)
Desmosomes (spot weld)
47
Q

Where are zona occludens found? What is characteristic of this?

A

Apically within the lateral domain, encircles the cell
Not a continuous seal (a focal fusion of leaflets of plasma membrane)

Focal fusion-> junctional proteins of adj cells transverse the plasma membrane and come into contact to occlude the ICS

48
Q

What is Afadin + Nectin + JAMS? What is specific of afadin?

A

zonula occludent proteins (ZO1, ZO2, ZO3)
-Faciliate interaction of occluden, claudin, JAMS w/ F-Actin

Afadin is embryo lethal (ZO proteins attach transmembrane proteins to inside of cell and signaling molecules)

49
Q

Where are tight junctions in the body? What do they prevent

A

BBB (astrocytes)

  • prevent lipids/membrane proteins from apical surface and lateral regions
  • signaling molecules to cell surface and link to actin filaments of cytoskeleton
50
Q

What are claudins + occludins a member ?

A

tetraspan family of proteins (

51
Q

What are nectins part of ?

A

transmembrane component of TJ, Ig Superfamily of proteins

52
Q

Where does paracellular transport occur?

A

Across the ZO (water, electrolytes + small molecules depends on the tightness of the ZO)

53
Q

What does the the tightness of ZO depend on?

A

Claudins to Occludins ration and the other proteins + aqueous channels in seal

54
Q

What are TJ composed of?

A

Claudins

55
Q

What are adherens junctions composed of?

A

E-Cadherin

56
Q

What are gap junctions composed of?

A

Connexins

57
Q

What are focal adhesions composed of?

A

Integrins

58
Q

What is the characteristics of the zonula adherens?

A

Continuous belt that encircles the belt junction

Actin cytoskeleton is linked
Important for maintaining structure

59
Q

In zonula adherens, what complex is it composed of?

A

Afadin-nectin complex

60
Q

What are the catherine in the zonula adherens?

A

Cadherins (desmocollins + desmogleins)

61
Q

What are the main transmembrane components of zonula adherens?

A

Cahderins (ca+ dependent)

62
Q

What do cadherins form?

A

Homotypic calcium-dependent interactions in the EC space w/ cadherins of the neighboring cell

63
Q

What is one of the main components in the folding of epithelial sheets into tubes, ducts for lateral specializations?

A

Cadherin-catenin-actin complex

64
Q

In human disease, during the epithelial mesenchymal transitions, with mesenchymal, what is down regulated, what is up regulated?

A

Cdherins are down regulated

Vimentin are upregulated

65
Q

What are desmosomes?

A

Spot welds for cell to cell adhesion
LATERAL SIDES
SUPER STRONG!!
(intermediate filaments)

66
Q

What are the parts of the desmosomes?

A

Plakophilin -> desmoglein
Pakoglobin-> desmocollin

both to make desmoplakin

67
Q

What are gap junctions?

A

Nexuses, gated channels that allow for ELECTRICAL + chemical communication between cells

68
Q

What can pass through gap junctions?

A

LArge molecules CANNOT pass

small molecules such as ions can

69
Q

Where is the most important place for gap junctions?

A

Cardiac

70
Q

What proteins are gap junctions formed out of?

A

Connexins

6 monomers to form a connexion

71
Q

What results in the closure of a gap junction?

A

High calcium concentration or low pH

72
Q

What are basal attachments?

A

Hemi-desmosomes

Focal adhesions

73
Q

What does PAS stain?

A

sugar molecules of proteoglycans

74
Q

What is basal lamina composed of?

A

ECM in contact with epithelial cells (laminins, collagens, glycoproteins, proteoglycans)

75
Q

What is the function of basal lamina?

A

Structural attachment for epithelial cells (Compartmentalization)
COULD RESULT IN METASTASIS Of tumors

76
Q

What are hemidesmosomes?

A

adhesive junctions attaching basal domain of epithelial cells to basal lamina
intracellular plaque attaches

77
Q

What is the basal lamina attached to the CT with?

A

Anchoring fibrils (typie VII collagen)

loops around collagen III in the reticular lamina and the ECM molecules in the basal lamina

78
Q

What is a focal adhesion?

A

Basal specialization
Link between ACTIN cytoskeleton + ECM proteins via interns

IMPORTANT for cell migration + wound healing

79
Q

What are the major transmembrane proteins involved in focal adhesions?

A

Integrins

Histology and Embryology (5 decks)

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