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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
Desmosomes function?
Strong adhesion. Linked to int filaments - tonofilaments - keratin.
25
Importance of desmosomes in structures?
Resist high mechanical stress. | Eg oral mucosa, gingiva, tongue, epidermis (polarised imp)
26
What us pemohigus foliacus?
Autoimmune response. To tmp. Antibodies against Desmoglein 1. Loss of adhesion.
27
Gjic - gap junction intercellular complex loss?
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
Where are gap junctions important?
Cardiac smooth muscle | Neurons - synapse
29
Hemidesmosomes?
Link to BM Integrins family proteins - link to keratin int filaments Associated with plaque.
30
BM detect at LM?
Add PAS stain. Seen single black line. Contain proteoglycans, proteins, glycoproteins.
31
3 layers in BM and composition of each?
Lamina lucida - entactin, glycoproteins, laminin, integrin Lamina densa - collagen 4, fibronectin, proteoglycans Lamina reticularis - collagen 1 3 6
32
Functions of BM - CMR LSM
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
Example of simple squamous epithelia? 5
Nucleus elongated. Thin cytoplasm | Lungs, lining of heart, bowmans capsule, endothelium, mesothelium
34
Simple cuboidal
Retina, terminal bronchioles, pancreas, liver, kidney ducts, ovaries
35
Simple columnar
Absorption and secretion. Microvilli - small intestine Portion of kidney, colon, gallblader, excretory ducts, stomach, small bronchioles
36
Pseudo-stratified epithelium? Microscope points
Need TEM to detect. | Presence of cilia and goblet cells therefore seen at LM.
37
Pseudostratified, more info?
All cells lie on basal membrane Nuclei of varying heights Not all cells reach free edge Stratified appearance,
38
Examples of pseudo stratified?
Mucosa of airways, ear canal, urethra, epididymis, large excretion duct of exocrine glands
39
Stratified squamous epithelia non keratinised. Where found?
Buccal mucosa, vagina, anal canal, esophageous, parts of larynx and pharynx.
40
Function and structure of SSE non keratinised?
``` Kept moist Stand mechanical stress Structure: superficial layer - 5 layers of squamous cells Spinosum layer - proliferating Basal layer ```
41
Stratified squamous epithelia, keratinised?
Epidermis. 5 layers. Avascular. Nutrients from CT. | Stratum, corneum, granulosum, spinosum, basal.
42
Function of dermal papillae and epidermal ridges?
Fingerlike connective projections. Indent deepest layers. Maintain anchoring Exchange of nutrients
43
Length of differentiation, from basale to straum?
28 days
44
Basale layer function?
Proliferation of cells Move to upper layers Lost to environment
45
Spinosum layer?
Spinous projections. | Large no of desmosomes - adhesion
46
Granulosum proteins
Loricrin and filaggrin
47
Lucidum layer
Contain cells with advanced keratinisation.
48
Corneum
Cornified cell envelop
49
Keratin protein in basale?
Keratin 5 and 14. 1 layer Proliferation Differentiation
50
Lipid production in skin and importance?
Stratum lucidum and corneum produce lipid mixed with sweat Lubricates skin Prevent dehydration
51
Why oral keratinocytes faster transition from basale to corneum than skin?
Missing desmocollin protein ( TMP ) desmosomes | Weakened adhesion.
52
4 examples of cells in squamous stratified epithelia keratinised skin?
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
Difference between pemphigus vulgarus and foliacus?
Foliacus - superficial skin blistering | Vulgarus - suprabasal skin blistering
54
Psoriasis mechanism?
BM destroyed. Factors released Underlying keratinocytes hyperproliferation Modification of epidermis
55
Stratified cuboidal epithelium examples?
Karge exocrine ducts, sweat glands, sebacous glands
56
Example of stratified columnar epithelia?
Male urethra, big gland ducts, larynx mucosa, conjuntiva
57
Transitional epithelium and examples?
Urethra, pelvis, urinary bladder Dome shaped cells may be binucleated Stretching - vesicles insert new pieces into PM
58
EMT - Epithelial cells to mesenchymal transition
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
EMT - down regulation of...?
``` E-cadherin Occludin (zo proteins) Desmocollin/glein Plakoglobin Cytokeratin 8,9,18 ```
60
EMT - Mesenchymal cell upregulation
``` aSMA isoform of actin FSP1 Fibronectin Vimentin Collagen 1 MMP 2&9 - hydrolyse BM ```
61
EMT Physiological and pathological?
Physiological - embryogenesis, healing damaged tissue | Pathological - cancer, fibrosis
62
Primary cilia microtubule arrangement? Where found? Function?
9 + 0 MT. arrangement Kidneys, liver, pancreas (when developing organs) Fluid flow sensor, passively bend, non-motile.

Histology (17 decks)

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