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Sarah - Structure > M+K Chapter 1 - Structure > Flashcards

M+K Chapter 1 - Structure Flashcards

1
Q

Plakoglobin and desmoplakins in desmosomes are the target for which acquired disease?

A

Paraneoplastic pemphigus

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2
Q

Desmoglein 3 in desmosomes is the targert for which acquired disease?

A

Pemphigus vulgaris

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3
Q

alpha-6, beta-4 intergrin in hemidesmosomes is affected in which congenital disease?

A

Junctional epidermolysis bullosa

Charolais cattle and Churra sheep

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4
Q

alpha-6, beta-4 intergrin in hemidesmosomes is the target for which acquired diseases?

A

Bullous pemphigoid, MMP

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5
Q

BPAG1e (BP230), collagen XVII (BP180, BPAG2, LAD-1) in hemidesmosomes are targeted in which acquired/autoimmune diseases?

A

Bullous pemphigoid, MMP, linear IgA bullous disease

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6
Q

Laminin alpha-3 beta-3 gamma 2 (laminin 5) in the lamina densa (BMZ) is affected in which congenital disease?

A

Junctional epidermolysis bullosa

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7
Q

Laminin alpha-3 beta-3 gamma 2 (laminin 5) in the lamina densa (BMZ) is the target in which acquired/autoimmune diseases?

A

MMP, acquired junctional epidermolysis bullosa

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8
Q

Type VII collagen in anchoring fibrils (BMZ) is affected in which congenital disease?

A

Dystrophic epidermolysis bullosa

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9
Q

Type VII collage in anchoring fibrils (BMZ) is the target in which acquired/autoimmune diseases?

A

Epidermolysis bullosa acquisita, type 1 bullous systemic lupus erythematosus

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10
Q

K5/K14 in intermediate filaments are affected in which congenital disease?

A

Epidermolysis bullosa simplex

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11
Q

K5/K14 in intermediate filaments are targets for which acquired/autoimmune disease?

A

Ocular cicatrical pemphigoid/MMP (people)

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12
Q

Which layer of the epidermis is intergrin expression normally confined to?

A

Basal layer

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13
Q

Name the three types of cytoplasmic filaments found in the keratinocyte cytoskeleton

A

Cytokeratin, actin, and microtubules (tubulin)

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14
Q

In which epidermal layer are lamellar bodies synthesised?

A

Stratum spinosum

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15
Q

An increase in calcium concentration in the stratum granulosum causes what to happen to lamellar bodies?

A

They fuse with the plasma membrane and secrete their contents into the intercellular space

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16
Q

Amide-linked fatty acids containing a long-chain amino alcohol (sphingoid base) are also know as what?

A

Ceramides

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17
Q

Which epidermal cells contain Birbeck granules?

A

Langerhans cells

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18
Q

What are Birbeck granules?

A

Invaginations of the plasma membrane and bound antigen

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19
Q

Laminin 332 (laminin 5) in anchoring fibrils binds intergrin alpha-6 beta-4 to which other element of the BMZ?

A

Collagen VII

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20
Q

BPAG2 (BP180, collagen XVII) is found in which part of the hemidesmosome?

A

Outer plaque of the hemidesmosome

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21
Q

Reticular fibres (reticulin - fine, branching structures) can be detected with which special stains?

A

Silver stains

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22
Q

Elastic fibers can be visualised with which stains?

A

Verhoff, Weigart and oxidised Weigart

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23
Q

What are elastic fibres made of?

A

Elastin (two unique cross-linked amino acids; desmosine and isodesmosine which give it it’s remarkable strength)
Microbfibrils (fibrillin and type VI collagen)

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24
Q

Which collagens make up 87%, 10% and 3% of the dermal collagen?

A

Collagen I 87%
Collagen III 10%
Collagen V 3%

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25
Q

Which cells are the major source of collagenases under normal remodeling conditions?

A

Dermal fibroblasts

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26
Q

Which cells, other than dermal fibroblasts, can produce collagenases?

A

Keratinocytes, neutrophils, eosinophils and macrophages

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27
Q

True or false, Shar Peis have higher levels of serum hyaluronic acid than other dogs?

A

True

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28
Q 
Where are the below found?
Collagen I, III and V
Collagen IV and V
Collagen VII
Collagen XII and XIV
A

Collagen I, III and V - dermis
Collagen IV (lamina densa) and V (lamina lucida) - BMZ
Collagen VII - BMZ anchoring fibrils
Collagen XII and XIV - FACIT (fibril-associated collagens with interrupted triple helices), believed to be influential in limiting the diameter of the dermal collagen fibrils and to help organise a proper dermal collagen I network

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29
Q

In animals affected with epidermolysis bullosa, sloughing of hooves is common - true or false?

A

True

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30
Q

What is the initial histopathological finding in EBS?

What is seen on histopathology in more advance stages?

A

Subepidermal separation with a minimal neutrophilic inflammation.

Extensive areas of intact full thickness epidermis are separated from the dermis, forming large clefts containing eosinophilic fluid, extravasated erythrocytes and occasional neutrophils

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31
Q

Can you see acantholytic keratinocytes in EBS?

A

Yes

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32
Q

In all animal species with JEB, oral multifocal ulcers are observed - true or false?

A

True

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33
Q

In the study by Nakai and Nasu, what were the ultrastructural properties of Merkel cells?

A
  1. Arrangement in clusters in the basal layer of the epidermis, oral mucosa and external follicular root sheath
  2. Inconstant link with nerve terminal
  3. Oval cell shape with large lobulated nuclei
  4. Spine-like and thick cytoplasmic processes interdigitating with surrounding keratinocytes
  5. Presence of desmosomes in the cell body or at the base of spine-like processes attaching to neighbouring keratinocytes
  6. Cytoplasm containing loosely arranged intermediate filaments and numerous dense-core granules arranged in the basal portion of the cytoplasm - cytoplasmic filaments in MKs were fewer and finer than those of keratinocytes.
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34
Q

Which vasoactive compounds are released from damaged cells causing a transient vasoconstriction and then vasodilation to allow fluids and cells to pass into the extravascular site of injury?

A

Histamine, serotonin and catecholamines

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35
Q

Dermal fibroblasts are stimulated to differentiate into alpha-smooth muscle actin expressing myofibroblasts by what?

A

transforming growth factor (TGF)-beta

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36
Q

The eventual result of the maturation phase is an acellular scar consisting of mostly which type of collagen?

A

Mostly collagen I

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37
Q

Which vitamin has been reported to significantly reverse the effects of corticosteroids on wound healing, and could be considered for adjunctive treatment in wound patients on chronic corticosteroid therapy?

A

Vitamin A

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38
Q

Positioning of ILCs in the epidermis is CCR6-dependent, and the maintenance requires which cytokines?

A

IL-7 and thymic stromal lymphopoietin (TSLP)

Produced by epithelial cells.

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39
Q

Which fibres link oxytalan (thin, most superficial) to elastic fibres (thicker, deepest)?

A

Elaunin

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40
Q

Which stain can demonstrate elastic, elaunin and oxytalan fibres?

A

Oxidised Weigert

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41
Q

What is the difference in composition of oxytalan, elaunin and elastic fibres?

A

Oxytalan is predominantly fibrillin microfibrils
Elaunin is a mixture of fibrillin and elastin
Elastic fibres are predominantly made of elastin

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42
Q

Tropoelastin is encoded by which gene?

A

Elastin (ELN)

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43
Q

Name two inflammatory/degenerative diseases of elastic fibres in veterinary species

A

Chronic progressive lymphoedema (of draught horses)
Solar elastosis
Erythema ab igne
Glucocorticoid effects

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44
Q

Marfan syndrome, a hereditary fibrillinopathy with lax and hyperelastic skin, has been reported in which veterinary species and affects which protein?

A

Cattle

Fibrillin 1

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45
Q

Which cytokine is sequestered in fibrillin fibres via LTBP?

A

TGF-beta (when released it stimulates collagen production by fibroblasts)
LTBP = latent TGF-beta binding protein

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46
Q

How do you differentiate cutis laxa from Ehlers-Danlos?

A

The hyperextensible skin rapidly moves back after stretching with Ehlers-Danlos and there is skin fragility and impaired wound healing

Cutis laxa has redundant skin and excessive folds (not reported in vet species yet)

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47
Q

Why do elastin fibres in solar elastosis stain with PAS?

A

There is an increased production and deposition of versican (a proteoglycan) on elastic fibres

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48
Q

Glucocorticoids reduce transcription of which dermal components?

A

Collagen I and III

Elastin

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49
Q

What is the role of tight junctions and adherence junctions?

A

Prevent diffusion of molecules between cells

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50
Q

What is the role of gap junctions?

A

Allow the diffusion of small molecules (e.g. calcium) between keratinocytes

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51
Q

Desmosomes link keratinocytes together by which intracellular structure?

A

Keratin filaments

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52
Q

What links intermediate filaments to plakoglobin and plakophlin in the desmosome?

A

Desmoplakin

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53
Q

Name the two cadherins that are in desomosomes

A

Desmogleins and desmocollins

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54
Q

Which is the more flexible protein, plakoglobin or plakophilin?

A

Plakophilin - it has a different segment between armadillo repeats which makes it more flexible

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55
Q

Name the epidermal plakins

A

Spectraplakins
BPAG1e/BP230
Envoplakin (corneodesmosomes and cornified envelope)
Periplakin (corneodesmosomes and cornified envelope)
Epiplakin
Desmoplakin
Plectin

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56
Q

True or false, plakophilin 1 (PKP1), desmocollin 1 (DSC1) and desmoglein 1 (DSG1) are expressed in the more superficial layers of the epidermis

A

True

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57
Q

What is epigenetics?

A

The study of changes in organisms caused by modification of gene expression rather than alteration of the genetic code itself.

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58
Q

Based on NGS studies, what are the main bacterial phyla found across different body sites in dogs?

A

Proteobacteria, Actinobacteria, Firmicutes, Bacteroidetes and Fusobacteria

Similar findings in cats although Bacteroidetes was more abundant

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59
Q

This EM image shows which structure? What do ODP and IDP stand for?

A

Desmosome

Outer dense plaque
Inner dense plaque
Midline
Plasma membrane

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60
Q

Name the structures of the desmosome

A

Keratin intermediate filaments
Dedmoplakin
Plakophilin and plakoglobin
Desmogleins and desmocollins

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61
Q

What makes up the outer dense plaque of the desomosme?

A

Desmoplakin heads, plakophilins, plakoglobin, cadherin cytoplasmic tails

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62
Q

What makes up the inner plaque of the desmosome?

A

Desmoplakin tails and keratin intermediate filaments

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63
Q

Which autoimmune diseases associated with desmoglein -1 have been reported in the dog?

A

PF
Mucocutaneous PV
Pemphigus vegetans

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64
Q

Which autoimmune diseases associated with desmocollin -1 have been reported in the dog?

A

Pemphigus Foliaceus (major antigen)

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65
Q

Name the epidermal members of the plakin family?

A

BPAG1-e (BP230), plectin, desmoplakin I/II, envoplakin, periplakin and epiplakin(-1)

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66
Q

Which autoimmune diseases associated with desmoplakin-1/2, envoplakin and periplakin have been reported in the dog?

A

PNP

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67
Q

Is this an image of footpad/haired skin or buccal mucosa?

A

Footpad/haired skin

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68
Q

Is this an image of footpad/haired skin or buccal mucosa?

A

Buccal mucosa

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69
Q

What are the green and yellow structures connecting microtubules and intermediate filaments?

A

Plectin

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70
Q

Which genetic diseases are associated with these structures?

A
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71
Q

In Chesakpeake Bay retrievers with ectodermal dysplasia and skin fragility, a mutation in which desomsomal structure leads to acantholysis?

A

Plakophilin-1

Loss of connection of desmoplakin to plakoglobin

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72
Q

Genetic EBS suprabasal form is reported in cows and associated with changes to which proteins?

A

Transglutaminase-5
Plakophilin-1
Desmoplakin
Plakoglobin

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73
Q

Name the hemidesmosome structures

A
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74
Q

Name the BMZ structures

A
75
Q

Junctional epidermolysis bullosa in Charolais cattle and Churra sheep is associated with a mutation in ITGB4 gene and affects which protein?

A

alpha-6 beta-4 integrin

76
Q

Which chain of alpha-6 beta-4 integrin is mostly extracelluar?

A

alpha-6 mostly extracellular

beta-4 mostly intracellular

77
Q

Collagen XVII forms the bulk of the anchoring fibrils in the BMZ and is a helix of which chains?

A

Homotrimer of alpha-1 chains

78
Q

Which vitamin is a cofactor for collagen formation?

Name another mineral that is a cofactor for collagen formation.

A

Vitamin C (ascorbic acid)

Copper

79
Q

__________ control and prevent the premature aggregation of triple helices and the formation of fibrils in the endoplasmic reticulum

A

Chaperones

80
Q

Extracellularly, procollagen ends are removed by which enzymes?

A

Metalloproteases

  • ADAMTS2: procollagen I amino-proteinase (procollagen I N-proteinase)
  • BMP1: procollagen I carboxy-proteinase (procollagen C-proteinase, Bone Morphogenetic Protein-1),
81
Q

Cross linking of tropocollagen monomers via lysyl oxidase enzyme to form microfibrils requires which mineral?

A

Copper

82
Q

True or false; Collagen III is the main component of reticulated (reticulin) fibrils, especially in lymphatic tissues

A

True

83
Q

Name the FACIT (Fibril-Associated Collagens with Interrupted Triple Helices) collagens and describe their role

A

Collagen XII and XIV

Influential in limiting the diameter of the dermal collagen fibrils and to help organize a proper dermal collagen I network (help regulate space between collagens)

84
Q

Which amino acid is important for triple helix formation in collagenogenesis?

A

Glycine

85
Q

What is removed from procollagen during processing?

A

N- and C-propeptides

86
Q

Where does lateral aggregation of collagen occur?

A

Golgi apparatus

87
Q

Where does propeptide assembly occur?

A

Endoplasmic reticulum

88
Q

Which enzymes cleave terminal peptides?

A

N: ADAMTS2
C: BMP1

89
Q

What are the extracellular steps of collagen fibril formation?

A
  1. Nucleators (e.g. collagen V) initiate fibril assembly at the fibroblast surface
  2. Protofibril deposition in the extracellular matrix
  3. Stabilisation by interaction with SLRPs and FACITs
  4. Fibril growth and maturation
  5. Linear and lateral growth to mature banded fibrils
90
Q

Name small leucine rich proteoglycans (SLRPs)

A 
Decorin
Biglycan
Fibromodulin 
Lumican 
Tenascin
91
Q

What is the role of small leucine rich proteoglycans (SLRPs)?

A

Steric hindrance
Collagen linking
Selection of lysine cross-links

92
Q

A form of classical Ehlers Danlos syndrome has been reported in the cat with skin tears, skin hyperextensibility, hip subluxation and perineal hernias; which gene was mutated?

A

COL5A1

93
Q

Dermatosparaxis is associated with a mutation in which enzyme?

A

ADAMTS2

94
Q

Which species has dermatosparaxis been reported in?

A

Cats
Cattle
Sheep

95
Q

True or false; collagen abnormalities can be variable in canine Ehlers Danlos syndrome

A

True

Collagen fibers can be relatively normal to short to almost no normal fibers

96
Q

Are elastic fibers affected in Ehlers Danlos syndrome?

A

No

97
Q

HERDA (Hereditary Equine Regional Dermal Asthenia) is seen in which breeds of horses?

A

Quarter Horse

American Paint

98
Q

Which images shows normal collagen?

A

Left: normal
Right: irregular and loosely organised fibrils

99
Q

HERDA is associated with a mutation in the gene encoding cyclophilin B; what is its role?

A
  • Role in triple helix formation

- Affects the folding of the carboxyl-terminal propeptide and collagen trimer formation

100
Q

In vivo studies have shown that topically administered glucocorticoids inhibit the transcription of mRNA encoding which types of collagen?

A

Collagen I and III

101
Q

What effect does photodamage have on dermal collagen?

A

Increased collagen degradation

Decreased collagen production

102
Q

What are the histopathological changes seen with photodamage?

A

Superficial alterations in dermal collagen usually include a hypocellular and homogeneous pale appearance.

103
Q

What are the three main reasons for reduced collagen in the dermis?

A

Genetic diseases
Glucocorticoids
Photodamage/ageing

104
Q

Feline skin fragility syndrome can be associated with spontaneous hyperadrenocorticism (48% of patients in one series), after iatrogenic glucocorticoid administration and with which other diseases?

A

Cholangiocarcinoma
Hepatic lipidosis,
Multiple endocrine neoplasia with hyperadrenocorticism
Chronic cholangiohepatitis with lipidosis
FIP infection
Generalized histoplasmosis
Multicentric follicular lymphoma

105
Q

What are the histopathological changes seen in feline skin fragility syndrome?

A
  • Thin epidermis and a severely atrophic dermis

- Profound attenuation of dermal collagen fibers with pale staining and disorganized appearance

106
Q

In GDSs with renal cystadenocarcinomas and nodular dermatofibrosis, what is seen in the dermis?

A

Increased normal collagen fibers

107
Q

In GDSs with renal cystadenocarcinomas and nodular dermatofibrosis, what is the mode of inheritance?

A

Autosomal dominant (homozygosity is lethal)

108
Q

Musladin-Lueke Syndrome - associated with a mutation in ADAMTSL2 - causes what clinical signs?

A 
Failure to thrive
Short stature 
Thick, tight and inelastic skin
Restricted joint mobility with a tiptoed gait
Craniofacial changes 
Gregarious temperament

Appears to stabilise around one year of age

109
Q

In GDSs with renal cystadenocarcinomas and nodular dermatofibrosis, a missense mutation occurs in which gene?

A

The folliculin (FLCN) gene encoding the protein folliculin

110
Q

What are the clinical signs in morphea (Localized Scleroderma)?

A

Well-circumscribed alopecic, smooth and sclerotic patches with a fairly shiny and hypopigmented skin appearance

111
Q

What is the prognosis for morphea?

A

They spontaneously regress

112
Q

What is an important differential for morphea?

A

Care must be taken to differentiate a morphea-like lesion from that of a post-traumatic scarring (cicatricial) alopecia.

Morphea-like lesions do not follow skin ulceration!

113
Q

Acquired reactive perforating collagenosis in cats causes exophytic adherent crusted papules and may be associated with wound healing; how can it be prevented?

A

Topical betamethasone

114
Q

What are flame figures?

A

Eosinophilic degranulation surrounding collagen fibers - not collagen degradation!

115
Q

Name the three fibers from superficial to deep

A

Oxytalan, elaunin and elastic

116
Q

Where does fibrillin microfibril assembly occur?

A

Bound to receptors on the fibroblast cell membrane where mature fibrillins assemble linearly (head-to-tail) and laterally (side-by-side; 8 molecules) to form polymers

117
Q

Marfan syndrome, associated with a fibrillin-1 mutation, is seen in which breeds of cattle?

A

Limousin crosses

Japanese black

118
Q

What is the main difference in clinical signs between cutis laxa and Ehlers-Danlos syndrome?

A

Decrease in skin elasticity in cutis laxa, and hyperelasticity in Ehlers-Danlos

119
Q

Mucinosis in Shar-Pei dogs is due to an excess secretion of high molecular weight HA following overtranscription or hyperactivity of which enzyme?

A

HAS2 enzyme

Low copy number = mucinosis
High copy number = familial Shar Pei fever

120
Q

What is abnormal in this image?

A

More, thicker, distorted elastic fibers are present

Will be PAS positive as versican (glycosaminoglycan) is present

121
Q

Which dermal collagen associated disease is this?

A

Erythema ab igne

Does not cause ulcers!

122
Q

Is hyaluronic acid (a GAG), sulphated?

A

No - the other GAGs are

123
Q

SLRPs bind to collagen I and are involved in regulating its fibril diameter and interfibrillar spacing; what is their other role?

A
  • Involved in fibrillin-1 fibrillogenesis.
  • Serve as signaling molecules, for example via their effect on TBF-beta, to regulate the deposition of extracellular matrix fibrils such as collagen type I.
  • Appear to regulate the intermolecular cross-linking of collagen, either directly or via binding to lysyl oxidase
124
Q

What are the clear spaces?

A

Mucin deposition

125
Q

Mucinosis in Shar-Pei dogs is due to an excess secretion of high molecular weight HA following overtranscription or hyperactivity of which enzyme?

A

HAS2 enzyme

126
Q

What is in the granules?

A

Hyaluronic acid

127
Q

Shar Peis with Shar-Pei Auto-Inflammatory Disease

(SPAID) have mutations associated with which genes?

A

MTBP - forms a complex that stabilizes MDM2, a protein that induces sterile inflammation and that inhibits the p53 pro-apoptotic tumor suppressor gene, thus promoting apoptosis

Transmitted with HAS2

128
Q

Mucinosis in hypothyroidism is associated with increased dermal deposition of what?

A

Hyaluronic acid

129
Q

What effect does UVB have on hyaluronic levels in the dermis?

A

Increases dermal hyaluronic acid

130
Q

What effect do glucocorticoids have on HAS2?

A

GCs inhibit the transcription of HAS2 mRNA - might be due to interference of GC with TGF signaling pathways

131
Q

In dogs, how many hair follicles make up a follicular compound?

A

10-30

132
Q

What separates the outer root sheath from the inner root sheath?

A

The companion layer

133
Q

What does the middle picture show?

A

Transition from infundibulum to isthmus (ring of tricholemmal keratin, opening of SG duct)

134
Q

Which part of the hair follicle is this?

A

Border of infundibulum and isthmus

135
Q

What are the arrows pointing to?

A

Top: Henle’s layer (cornifies first)
Bottom: Huxley’s layer

136
Q

At which part of the hair follicle is the inner root sheath fully cornified?

A

Isthmus

137
Q

Which image is the inferior portion of the hair follicle and why?

A

Bottom

Huxley layer not cornified

138
Q

Which growth phase are these hairs in?

A

Catagen

Retracting strand, apoptotic cells, different shape to dermal papilla, tricholemmal keratin anchoring the hair

139
Q

Anagen or telogen?

A

Anagen

140
Q

Anagen or telogen

A

Telogen

Bright eosinophilic keratin

141
Q

Which structures are part of intercellular cohesions in the hair shaft?

A

Desmogleins and desmocollins

142
Q

Do puppies have secondary or primary hair follicles at birth?

A

Primary only - secondary develop ~12 weeks

143
Q

KRT71 is associated with which coat phenotype?

A

Curly

Hairlessness in Sphynx cats

144
Q

FGF5 is associated with which coat phenotype?

A

Long hair

145
Q

RSPO2 is associated with which coat phenotype?

A

Wire hair/furnishings

146
Q

LPAR6 is associated with which coat phenotype in cats?

A

Curly coat in Cornish Rex and German Rex

147
Q

Naked foal syndrome in Akhal Teke horses is inherited as a monogenic autosomal recessive trait and a nonsense variant of which gene?

A

ST14

148
Q

Mutations in which gene cause hairlessness in American terriers and Scottish deerhounds?

A

SGK3

149
Q

A mutation of which gene leads to colour dilution?

A

MLPH (melanophilin gene)

150
Q

Are there increased number of kenogen follicles seen in dogs with endocrinopathies compared to normal dogs?

A

Yes

151
Q

Witches feet follicles are seen with which cause of alopecia in dogs?

A

Recurrent flank alopecia

152
Q

Glucocorticoids and oestrogens have what effects on the hair growth cycle?

A
  • Induce premature catagen
  • Induce premature telogen
  • Inhibit onset of anagen
153
Q

T4/T3 have what effects of the hair growth cycle?

A

Initiate and prolong anagen

154
Q

Which types of alopecia can be classified as ischemia not associated with primary vascular pathology?

A

Canine traction alopecia

Post-traumatic alopecia

155
Q

Which types of alopecia can be classified as ischemic dermatopathies (cutaneous vasculitis / vasculopathy)?

A
  • Canine familial dermatomyositis
  • Juvenile-onset ischemic dermatopathy without proven breed predilection
  • Generalized postrabies vaccination-associated disease
  • Adult onset generalized idiopathic ischemic dermatopathy
  • Jack Russel Terrier vasculitis
156
Q

Plectin through its actin-binding domains connects keratin filaments to nucleus by binding to _________

A

Nesprin-3

157
Q

Curly coat in Fleckvieh and German angus cattle is due to mutation on keratin ____.

A

KRT 27

158
Q

How many extracellular domains do the desmosomal cadherins have?

A

4 (EC1 TO EC4)

159
Q

Which hormones initiate and prolong anagen?

A 
Thyroid
Corticotropin
Melatonin
Androgens
Growth hormone
160
Q

Which hormones inhibit the hair cycle?

A 
Cortisol
Oestrogen
Corticotropin-releasing hormone
Corticotropin
Prolactin
Parathyroid-related peptide
161
Q

Name three growth factors that induce or prolong anagen

A 
FGF 7
Hepatocyte growth factor
Insulin-like growth factor 1
Sonic hedgehog
Keratinocyte growth factor, WNTs, beta-catenin, TGF-alpha
Nerve growth factor
GDNF
162
Q

Name two growth factors that inhibit the hair cycle

A 
Epidermal growth factor
FGF 2, FGF 5
Brain derived neurotropic factor
Neurotrophin 3, 4
TGF-alpha
TGF-beta 1/2
163
Q

What effect does ciclosporin have on the hair cycle?

A

Stimulates it

164
Q

Which cells are thought to be the primary target to hormones affecting the hair cycle?

A

Dermal papilla cells

165
Q

If activation of melanocortin 1 receptors (MCR1) on melanocytes leads to eumelanin production, what does inhibition of MCR1 lead to?

A

Pheomelanin production

166
Q

Fatty acids are converted to what products by keratinocytes?

A

Phospholipids

Ceramides (sphingomyelin, glucosylceramide)

167
Q

Which essential fatty acid forms part of ceramides 1, 4 and 9?

A

Linoleic acid

168
Q

Polyunsaturated fatty acids are precursors of what?

A

Eicosanoids

169
Q

How are phospholipids metabolised to prostaglandins and leukotrienes?

A

Phospholipase A metabolises phospholipids to polyunsaturated fatty acids. They are subsequently metabolised by cyclooxygenase and lipoxygenase to prostaglandins and leukotrienes

170
Q

What is the arrow pointing to?

A

Merkel cells in a tylotrich pad

Merkel cells contain a large cytoplasmic vacuole that displaces the nucleus dorsally. They are found in/just below the basal layer

171
Q

What does this EM image show?

A

Birbeck granule in a Langerhans cell

172
Q

The inner root sheath keratinises and disintegrates at which level of the follicle?

A

When it reaches the isthmus

173
Q

Which hairs are slow- and which hairs are rapid-adapting mechanoreceptors?

A

Sinus hairs = slow

Tylotrich hairs = rapid

174
Q

Sebaceous glands are not found at which body sites?

A

Footpad and nasal planum

175
Q

Androgens cause sebaceous gland hypertrophy; which hormones cause sebaceous gland involution?

A

Oestrogen and glucocorticoids

176
Q

Where do epitrichial sweat gland ducts open in the hair follicle?

A

The pilary canal in the infundibulum, above the sebaceous gland duct

177
Q

Which parts of the skin do the deep, middle and superficial plexus of blood vessels supply?

A

Deep: subcutis, lower portion of the hair follicle and sweat glands
Middle: arrector pili, middle portion of the hair follicle and sebaceous glands
Superficial: upper portion of the hair follicle and epidermis

178
Q

What regulators of leukocyte trafficking are found on endothelial cells?

A

E- and P-selectin
ICAM1
VCAM1

179
Q

Substance P, released by sensory nerve fibres and keratinocytes, binds to tachykinin and neurokinin 1 receptors and has what function in the skin?

A
  • Inflammation
  • Upregulation of cell adhesion molecules
  • Priming of mast cells
  • Pruritus
180
Q

Keratinocytes and _____________ are important sources of nerve growth factor

A

Mast cells

181
Q

What are these structures?

A

Pacinian corpuscles

182
Q

Which type of opioids are pruritic at spinal level?

A

u-opioids

183
Q

Which interleukins are pruritogenic?

A

IL-2 and IL-31

184
Q

Damage to which part of the hair follicle leads to lack of capability to grow?

A

Stem cell bulge (isthmus)

Sarah - Structure (5 decks)

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