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Histology > Epithelia > Flashcards

Epithelia Flashcards

0
Q

What are cells and ECM defined as?

A

Tissues

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1
Q

5 characteristics of epithelia

A 
Form a BM
Lay on CT
Formed by cells
Avascular therefore
...gain nutrients from connective tissue
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2
Q

4 types of tissue

A

Epithelia, muscular, neural, connective

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3
Q

4 functions of epithelia

A

Secretion, absorption, lining pathways, protect connective tissue below

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4
Q

2 characteristics of 2 adjacent epithelia?

A

Continuous with each other

Space between small - 15-30nm

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5
Q

Epithelia formation in lining and glandular tissue?

A

Lining - form tight sheets

Glandular - form aggregates

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6
Q

3 distinct characteristics of a epithelial cell?

A

Cytoskeleton different roles
Morpho-functional polarity
Apical, lateral, basal parts have different specialisations at PM

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7
Q

Epithelia cytoskeleton and functions?

A

Microfilaments - microvilli and terminal web
Int filaments - tonofilaments - keratin - add stability
Microtubules - MTOC - movement of vesicles.

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8
Q

Microtubules MTOC arrangement?

A

Centrosomal MT - radial arrangement
Non centrisomal MT - non radial, apical and basal axis, linear. (-) apical (+) basal
Polymerisation at. + end. What req?

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9
Q

Morpho-functional polarity?

A

Eg intestine and secreting cells - columnar epithelium
Apical - ER, vesicles
Basal - Golgi, mitochondria. Basal infoldings - increase sa…

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10
Q

3 apical specialisations?

A

Microvilli, cilia, stereocilia

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11
Q

Microvilli

A

Covered by glycocalx ( glycoproteins and gags )
Form brush border (small intestine)
Only seen at EM not LM

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12
Q

Cilia?

A

Movement of material on apical surface. Eg mucus, dust, bacteria.
Found in higher respiratory tract. Fallopian tubes.

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13
Q

Cilia structure

A

9 pairs of MT around 1 central pair (axonem)

Attached to basal body via 9 triplets of MT

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14
Q

Stereocilia?

A

Up to 100um therefore seen at LM and EM.
No basal body.
Actin filaments (parallel array).
Involved in absorption, function similar to microvilli
Epididymis - release specific factors - maturation of sperm

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15
Q

Baso-lateral specialisations (basal)

A

Basal infolding.
High no of mitochondria and Golgi.
Seen in kidneys, exocrine glands, salivary glands.

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16
Q

3 types of lateral junctions

A

Occluding, anchoring, communication

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17
Q

5 types of junctions and their type

A 
Tight occluding - zonula occludens occluding therefore prevent transmembrane movement of molecule.
Adhesion - zonula adherens anchoring 
Desmosomes - macula adherens anchoring
Gap junction - communication.
Hemidesmosomes - anchor cell to BM
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18
Q

Gap junctions / nexuses

A

Allow ions, small molecules, metabolites
Variable no. pores
12 sub units of connexon - phosphorylation = closed.
Each connexon contain 6 subunits of connexin (Integral membrane proteins)

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19
Q

Tight junctions, functions and characteristics?

A

Occluding.
Point to point fusion, prevent transmembrane movement.
TEM - seen as series of loops between cells.
Proteins - occludin and claudin connected to ZO proteins - actin filaments

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20
Q

What is jam?

A

Junction adhesion complex.
Found in tight junctions.
Glycoproteins
Cross at the widest point in between tight junctions ( the loops )

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21
Q

What is a paracrine gland?

A

Epithelia secrete substance not reach bloodstream

Effect cells in close vicinity

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22
Q

Loss of E - Cadherin (tmp) in zonula adherens?

A

Methylation, mutation, transcriptional repression, post-transcriptional down reg.
Lead to loss of adhesion. B-catenin released into cytoplasm. Translocated into nucleus. Effect gene expression.

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23
Q

Desmosomes proteins involved? Tmp imp

A

Tmp - desmocollin(basal), desmoglein (apical)

Imp - plakoglobin, plakophillin

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24
Q

Desmosomes function?

A

Strong adhesion. Linked to int filaments - tonofilaments - keratin.

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25
Q

Importance of desmosomes in structures?

A

Resist high mechanical stress.

Eg oral mucosa, gingiva, tongue, epidermis (polarised imp)

26
Q

What us pemohigus foliacus?

A

Autoimmune response. To tmp. Antibodies against Desmoglein 1. Loss of adhesion.

27
Q

Gjic - gap junction intercellular complex loss?

A

Loss of cell communication. May lead to cancer. Tumour spead. Loss of bm therefore to CT then blood stream.
Reverse by adding connexin - gap junction - reverse tumour - tumour suppressor gene .

28
Q

Where are gap junctions important?

A

Cardiac smooth muscle

Neurons - synapse

29
Q

Hemidesmosomes?

A

Link to BM
Integrins family proteins - link to keratin int filaments
Associated with plaque.

30
Q

BM detect at LM?

A

Add PAS stain.
Seen single black line.
Contain proteoglycans, proteins, glycoproteins.

31
Q

3 layers in BM and composition of each?

A

Lamina lucida - entactin, glycoproteins, laminin, integrin
Lamina densa - collagen 4, fibronectin, proteoglycans
Lamina reticularis - collagen 1 3 6

32
Q

Functions of BM - CMR LSM

A

C cell polarity
M metabolism
R regulate cell repair mech and regulation
L link to CT
S selective barrier. Allow certain mat thru
M prevent metastasis of cancerous cells

33
Q

Example of simple squamous epithelia? 5

A

Nucleus elongated. Thin cytoplasm

Lungs, lining of heart, bowmans capsule, endothelium, mesothelium

34
Q

Simple cuboidal

A

Retina, terminal bronchioles, pancreas, liver, kidney ducts, ovaries

35
Q

Simple columnar

A

Absorption and secretion.
Microvilli - small intestine
Portion of kidney, colon, gallblader, excretory ducts, stomach, small bronchioles

36
Q

Pseudo-stratified epithelium? Microscope points

A

Need TEM to detect.

Presence of cilia and goblet cells therefore seen at LM.

37
Q

Pseudostratified, more info?

A

All cells lie on basal membrane
Nuclei of varying heights
Not all cells reach free edge
Stratified appearance,

38
Q

Examples of pseudo stratified?

A

Mucosa of airways, ear canal, urethra, epididymis, large excretion duct of exocrine glands

39
Q

Stratified squamous epithelia non keratinised. Where found?

A

Buccal mucosa, vagina, anal canal, esophageous, parts of larynx and pharynx.

40
Q

Function and structure of SSE non keratinised?

A 
Kept moist
Stand mechanical stress
Structure: superficial layer - 5 layers of squamous cells
Spinosum layer - proliferating
Basal layer
41
Q

Stratified squamous epithelia, keratinised?

A

Epidermis. 5 layers. Avascular. Nutrients from CT.

Stratum, corneum, granulosum, spinosum, basal.

42
Q

Function of dermal papillae and epidermal ridges?

A

Fingerlike connective projections. Indent deepest layers.
Maintain anchoring
Exchange of nutrients

43
Q

Length of differentiation, from basale to straum?

A

28 days

44
Q

Basale layer function?

A

Proliferation of cells
Move to upper layers
Lost to environment

45
Q

Spinosum layer?

A

Spinous projections.

Large no of desmosomes - adhesion

46
Q

Granulosum proteins

A

Loricrin and filaggrin

47
Q

Lucidum layer

A

Contain cells with advanced keratinisation.

48
Q

Corneum

A

Cornified cell envelop

49
Q

Keratin protein in basale?

A

Keratin 5 and 14.
1 layer
Proliferation
Differentiation

50
Q

Lipid production in skin and importance?

A

Stratum lucidum and corneum produce lipid mixed with sweat
Lubricates skin
Prevent dehydration

51
Q

Why oral keratinocytes faster transition from basale to corneum than skin?

A

Missing desmocollin protein ( TMP ) desmosomes

Weakened adhesion.

52
Q

4 examples of cells in squamous stratified epithelia keratinised skin?

A

Keratinocytes
Melanocytes - RER syn tyrosine. Melanin and tyrosine stores in lysosomes (melanosomes)
Merkel cells - tactile receptors
Langerhans - immune response - present antigen vis lymph nodes to lymphocytes.

53
Q

Difference between pemphigus vulgarus and foliacus?

A

Foliacus - superficial skin blistering

Vulgarus - suprabasal skin blistering

54
Q

Psoriasis mechanism?

A

BM destroyed.
Factors released
Underlying keratinocytes hyperproliferation
Modification of epidermis

55
Q

Stratified cuboidal epithelium examples?

A

Karge exocrine ducts, sweat glands, sebacous glands

56
Q

Example of stratified columnar epithelia?

A

Male urethra, big gland ducts, larynx mucosa, conjuntiva

57
Q

Transitional epithelium and examples?

A

Urethra, pelvis, urinary bladder
Dome shaped cells may be binucleated

Stretching - vesicles insert new pieces into PM

58
Q

EMT - Epithelial cells to mesenchymal transition

A

Epithelium cell - layers connected, junctions, not concave, polarity(and of cytoskeleton arrangement), connected to bm, no syn of collagen, little extracellular space, not motile.
Mesenchymal cell - no polarity, concave, syn collagen and extracellular space, extracellular space exceeds total vol of cells, motile, no laminins

59
Q

EMT - down regulation of…?

A 
E-cadherin
Occludin (zo proteins)
Desmocollin/glein
Plakoglobin
Cytokeratin 8,9,18
60
Q

EMT - Mesenchymal cell upregulation

A 
aSMA isoform of actin
FSP1
Fibronectin
Vimentin
Collagen 1 
MMP 2&9 - hydrolyse BM
61
Q

EMT Physiological and pathological?

A

Physiological - embryogenesis, healing damaged tissue

Pathological - cancer, fibrosis

62
Q

Primary cilia microtubule arrangement?
Where found?
Function?

A

9 + 0 MT. arrangement
Kidneys, liver, pancreas (when developing organs)
Fluid flow sensor, passively bend, non-motile.

Histology (17 decks)

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