Dermatology Flashcards

1
Q

Where does the epidermis originate from?

A

Ectoderm

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2
Q

Where does the dermis arise from?

A

Dermis

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3
Q

When does the epidermis form?

A

Week 4

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4
Q

What happens during the first stage of skin development?

A

Epidermis forms by week 4- single basal layer of cuboidal cells- superior of mesoderm layer

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5
Q

Which cells form the basal layer during initial stages of skin development?

A

Cuboidal cells

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6
Q

When does the second stage of skin development occur?

A

Week 5

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7
Q

What types of cells form the periderm?

A

Squamous non-keratinising cuboidal cells, generates white waxy protective substance - vernix caseosa

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8
Q

What is the white waxy protective substance that forms the periderm?

A

Vernix caseosa

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9
Q

Which is the deepest epidermal layer?

A

Straum germinativum

Stratum basale

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10
Q

Which layers of epidermis forms deep to superficial? (Stage 3)

A

Straum Spinosum
Stratum Granulosum
Stratum Lucidum (palms and soles)
Stratum Corneum

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11
Q

What do epidermal ridges form?

A

Dermal papillae

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12
Q

At which weeks do lanugo hair and hair follicles in stratum germinativum form?

A

Weeks 9-13

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13
Q

How do melanocytes interact with keratinocytes?

A

Dendritic interactions

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14
Q

What is the principal function of melanocytes?

A

Responsible for melanin secretion through melanogenesis

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15
Q

Which cells do melanocytes arise from?

A

neural crest

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16
Q

What term is used to describe progenitor melanocytes?

A

Melanoblasts

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17
Q

Where do melanocyte stem cells reside?

A

Hair follicle bulge

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18
Q

Which receptor regulates the quantity of melanin secretion?

A

Melanocortin 1 receptor (MC1R)- G protein coupled receptor

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19
Q

Which agonist mediates melanogenesis via MC1R?

A

Alpha-melanocyte stimulating hormone (Alpha-MSH)

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20
Q

What is the rate limiting enzyme in melanogenesis?

A

Tyrosinase

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21
Q

Which molecule forms the precursor of melanin?

A

Eumelanin

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22
Q

Which gene increases expression of POMC?

A

p53

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23
Q

What effect does increased exposure to UV radiation have?

A

keratinocyte receives increased exposure to UV radiation, DNA damage induces mutation.
Stimulates tumour suppressor gene, p53 –> increases expression of POMC, precursor or alpha-MSH, this increases expression of enzymes and proteins required for synthesis of melanin and melanocytes

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24
Q

Which transcription factors is increases melanogenesis?

A

MITF

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25
Q

Which downstream melanogenic proteins increase melanin content?

A

Pmel17, MART-1, TYR, TRP1

DCT

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26
Q

Which melagenic proteins play a role in melanosomes?

A

MART-1

MPL-1

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27
Q

Increased expression of _____ in keratinocytes increases uptake & distribution of melanosomes by keratinocytes:

A

PAR-2

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28
Q

How are melanosomes transferred into keratinocytes?

A

Pseudopodia of melanocyte interlock with keratinocytes, enabling transfer of melanosome; internally degranulates & releases melanin

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29
Q

Which protein reverses effects & elicits production of phenomelanin?

A

Agouti signalling protein (ASP)

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30
Q

Which hormone up regulates MCIR expression?

A

ACTH

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31
Q

Which type of epithelial cells form the epidermis?

A

Composed of keratinised, stratified squamous epithelium

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32
Q

Is the epidermis avascular or vascular?

A

Avascular

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33
Q

What are the layers (deep to superficial) of the epidermis?

A

Stratum Basale
Stratum Spinosum
Stratum Granulosum
Stratum Corneum

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34
Q

Which epidermal layer is found exclusively in palms and soles?

A

Lucidum

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35
Q

Which epidermal layers are keratinocytes located within?

A

All layers besides stratum basal

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36
Q

Which molecule is stored & synthesised within keratinocytes?

A

Keratin

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37
Q

What is the function of keratin?

A

Intracellular fibrous protein that provides strength and water resistance

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38
Q

How are keratinocytes replaced in the stratum corneum?

A

Replaced by cells from deeper layers

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39
Q

What is the function of the stratum basale?

A

Attaches epidermis to the basal lamina cells bound to dermis
Basal cells precursors to keratinocytes
Melanocytes produce melanin
Merkel cells

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40
Q

Which structure located on the superficial dermis increases the strength of connection between the epidermis & dermis?

A

Dermal papilla

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41
Q

Which cells are precursors to keratinocytes?

A

Basal cells

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42
Q

What is the fate of mitotically produced keratinocytes?

A

Superficially accumulate away from the stratum basal

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43
Q

What is the function of Merkel cells?

A

Functions as receptor, responsible for stimulating sensory touch fibres

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44
Q

Where are Merkel cells located?

A

Stratum Basle

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45
Q

Which epidermal layer contains melanocytes?

A

Stratum Basale

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46
Q

How are cells connected within the stratum spinosum?

A

Via desmosomes

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47
Q

What are desmosomes?

A

Adhesion protein complexes present in the epidermis

Function:Anchor keratin intermediate filaments to cell membrane and bridge adjacent keratinocyte, enables cells to withstand trauma

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48
Q

Where are Langerhans cells located?

A

Express macrophage function

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49
Q

Why are the cell membranes within the stratum granulosum thick?

A

Due to keratin presence, and keratohyalin

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50
Q

What granules accumulate within the stratum granulosum?

A

Lamellar granules,

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51
Q

In which epidermal layer, does the nuclei and cell organelles disintegrate?

A

Stratum granulosum

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52
Q

What is the most superficial layer of the epidermis?

A

Stratum corneum

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53
Q

What is the function of the stratum corneum?

A

Keratininsation of cells prevents penetration of microbes, and the dehydration of underlying tissues.
Provides a mechanical protection against abrasion

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54
Q

How is the dermis separated from the epidermis?

A

Laye of connective tissue and subcutaneous fat, deep to epidermis, and separated by basement membrane

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55
Q

What is the structure of keratinocytes?

A

Filamentous cytoskeletons comprise of actin-containinng microfilaments
Tubulin-containing microtubules and intermediate filaments (Keratins)

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56
Q

What are the 5 roles of keratins?

A
Structural properties
Cell signalling
Stress response
apoptosis
wound healing
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57
Q

Connexons are _____ junctions?

A

Gap junctions

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58
Q

What is the role performed by connexon gap junctions?

A

Clusters of intercellular channels, directly form connections between cytoplasm of adjacent keratinocytes

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59
Q

What types of junctions are transmembrane structures which engage with actin skeletons?

A

Adherens junctions

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60
Q

Which type of junctions play a role in barrier integrity and cell polarity?

A

Tight junctions

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61
Q

Which cells are menlanocytes intimately associated with?

A

Keratinocytes

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62
Q

How is melanin distributed into keratinocytes?

A

Formation of a epidermal melanocyte unit, synthesised by melanocytes and disturbed into melanosomes into keratinocyte

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63
Q

What function is performed by Langerhans cells?

A

Reside within the epidermis as immune sentinels
Cells determine appropriate adaptive immune response (inflammation or tolerance) by interpreting microenvironmental context
Functionally, Langerhans cells express antigen presenting properties; behaving as dendritic cells

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64
Q

Where are Merkel cells located?

A

Within the basal layer of the epidermis

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65
Q

What is the function of Merkel cells?

A

Exhibit mechanosensory receptor properties that mediate sense of touch and follicle movement

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66
Q

Which inflammatory host cells reside within the epidermis?

A

Mast cells

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67
Q

Which Ig mediated reactions?

A

IgE-mediated reactions through FceRI receptors upon activation

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68
Q

Which main inflammatory cytokine is released from mast cells?

A

Histamines

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69
Q

The basement membrane is considered to be the ______ junction:

A

Dermal-epidermal

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70
Q

What comprises the basement epidermal-dermal junction?

A

Glycoproteins and proteoglycans

Collagen (IV, VII, laminin, integrins)

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71
Q

What is the function of the basement membrane?

A

Cell adhesion and cell migration

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72
Q

Which cells predominantly produce collagen?

A

Fibroblasts

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73
Q

Which molecules are found within the dermis?

A

Compose of interconnected mesh of elastin and collagenous fibres

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74
Q

What is the most superficial layer of the dermis?

A

Papillary layer

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75
Q

Which epidermal layer does the papillary layer project into?

A

Stratum basal of the epidermis, projection as dermal papillae

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76
Q

What projections are formed via the papillary layer into the epidermal stratum basale?

A

Dermal papillae

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77
Q

What type of connective tissue forms the dermis?

A

Loose areolar connective tissue.

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78
Q

Which two main types of cells reside within the papillary layer?

A

Adipocytes and fibroblasts

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79
Q

Which touch receptors are located within the papillary layer of the dermis?

A

Meissner corpuscles

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80
Q

Which dermal layer is deep to the papillary layer?

A

Reticular layer

81
Q

Which type of connective tissue forms the reticular layer?

A

Dense irregular connective tissue

82
Q

What properties are exhibited by the reticular layer?

A

Dense irregular connective tissue exhibit multilateral force resistant properties attributing to the flexibility of the skin
Majority of the dermis is comprised of the reticular layer

83
Q

Which supplies are found within the papillary layer?

A

Lymphatic capillaries, nerve fibres , and Meissner corpuscles

84
Q

Where is the sensory, vascular and sympathetic supplies found within the dermis?

A

Within the reticular layer

85
Q

Which types of fibres provide elastic properties which facilitate movements within the reticular layer?

A

Elastin fibres

86
Q

Which proteins are found within the dermal reticular layer?

A

Collagen (Type 1 and 3)
Elastin
Fibrillin

87
Q

Which types of collagen is found within the reticular layer?

A

Type 1 and 3

88
Q

Which types of glycoproteins are located within the dermal reticular layer?

A

Fibronectin, fibrin integrins

89
Q

Which ground substance molecules are located within the dermal reticular layer?

A

Dermal collagen, and elastic tissue (glycosaminoglycan and proteoglycan)

90
Q

Which is the main cell type within the dermis?

A

Fibroblasts

91
Q

What are the 6 main cell types in the dermis?

A
Fibroblasts
Mast cells
Neutrophils
Lymphocytes
Histiocytes
Dermal dendritic cell
92
Q

which types of glands secrete sweat?

A

Sudoriferous glands

93
Q

What are sweat glands classified as?

A

Merrocrine glands

Secretions are excreted by exocytosis through a duct

94
Q

Which types of sweat glands are associated with hair follicles?

A

Apocrine sweat glands

95
Q

Which types of sweat glands produce hypotonic sweat for thermoregulation, residing deep in the dermis?

A

Eccrine glands, duct rising up to pore on skin surface, seat released

96
Q

Describe the vasculature of the dermis:

A

Deep and superficial vascular plexus does not cross into epidermis

97
Q

How are the eccrine and apocrine glands innervated?

A

Autonomic nervous system

98
Q

Which type of gland is innervated by cholinergic synapses?

A

Eccrine

99
Q

Which glands are stimulated by adrenergic synapses?

A

Eccrine and apocrine

100
Q

What is a pilosebaceous unit?

A

Structure consist of hair, hair follicle, arrector pilli muscle and sebaceous gland

101
Q

Where are the corpuscles and cutaneous receptors located in respect to afferent nerves?

A

Located at the terminals of the afferent neurones, encapsulated in elaborate cellular corpuscles.

102
Q

Which corpuscles responds to light touch, and senses low-frequency stimulation at the level of dermal papilla?

A

Meissner corpuscles

103
Q

What is the function of Ruffini corpuscles?

A

Slow acting mechanoreceptors, sensitive to skin stretch, deep in dermis, spindle-shaped, high density around fingernails, monitors slippage

104
Q

Where are Ruffini corpuscles predominantly located?

A

High density around fingernails

105
Q

Which types of mechanoreceptors detect pressure and vibration?

A

Pacinian corpuscle

106
Q

Which endings detect thermal and noxious stimuli?

A

Free endings

107
Q

Which three receptors detect light touch?

A

Meissner
Merkel cells
Free nerve endings

108
Q

Which receptors detect pressure and touch?

A

Merkel
Ruffini
Pacinian
Free nerve endings

109
Q

Which nerve endings detect vibration?

A

Pacinian

Meissner

110
Q

Which junctions do the dendritic processes extend through of Langerhan cells?

A

Tight junctions, to sample the stratum corneum

111
Q

What is the function of Langerhans cells?

A

Promotes expansion and activation of skin resident regulatory cells

Detection of pathogen-associated molecular patterns (PAMPs) –> rapid initiation of innate antimicrobial responses

Induction of adaptive responses (power and specific of T cells)

Forms an interlocking network through Langerhans and dendritic interactions which entrap pathogens

112
Q

What 3 methods is conducted within the dermis to ensure immune surveillance?

A

Tissue-resident T cells
Macrophages
Dendritic cells

113
Q

Which antimicrobial peptides are secreted (derived from keratinocytes)?

A

Defensins

Cathelicidins

114
Q

What effect does cathelicidin have?

A

Expression is enhanced by keratinocyte activity, predominantly residing within granules of the superficial epidermis –> Innate immune defence

115
Q

Which epidermal layer restricts water and protein loss?

A

Stratum corneum (cornfield cell envelope)

116
Q

What effect does high output cardiac failure and renal failure have on the epidermis?

A

Extensive skin disease

117
Q

What effect does subcutaneous fat exhibit within the skin?

A

Exhibits shock absorbing properties, protecting muscles and bones from significant impact and traumas

118
Q

Which type of UV is the epidermis protected from via melanin?

A

UVB

119
Q

Which nerve endings exhibit the ability to detect changes in temperature?

A

Krause end bulbs

Ruffini corpuscles

120
Q

Which centre detects temperature within the hypothalamus?

A

Thermoregulatory centre

121
Q

What occurs in the skin within a warm environment?

A

Vasodilators occurs, sphincter muscles around the arterioles leading to superficial capillaries are not stimulated to contract and therefore relax.
More flood flow, cooling by conduction and radiation increased

arteriovenous shunt is stimulated to close, thereby enabling greater volume of blood traversing through the capillaries, increased ability of heat loss.

Eccrine glands respond to core internal and peripheral temperature; innervation by cholinergic sympathy nerves stimulates merocrine secretion of hypotonic solutions, secreting water to epidermal surface, where heat is dissipated through evaporation

122
Q

What is the precursor molecule located within the epidermis for vitamin d?

A

7-dehydrocholesterol

123
Q

What is 7-dehydroxycholesterol converted into?

A

Pre-Vitamin D3

124
Q

How does UV play a role in the formation of vitamin D3?

A

Stimulates the action of pre-vitamin D3 conversion into the vitamin D3 within the stratum basale, and stratum spinosum of the epidermis by keratinocyte

125
Q

Which layer is subcutaneous fat located?

A

Hypodermis layer

126
Q

What type of tissue comprises the hypodermis?

A

Vascularised, areolar connective tissue, and abundant adipose tissue, functions as a mode of triglyceride storage.

127
Q

How is fat stored in the hypodermis?

A

Lipogenesis, glucose is converted into triglycerides , stored within adipocytes

128
Q

What effect does Leptin have?

A

Adipocytes secrete adipokines including leptin, Stimulates lateral hypothalamic receptors to inhibit hunger, and stimulates satiety

129
Q

Where does hair root end in the dermis?

A

Hair bulb

130
Q

Which structure is surrounded by the hair bulb?

A

Hair papilla

131
Q

What does the hair papilla contain?

A

Contains blood capillaries and nerve endings from the dermis

132
Q

What are the 6 functions of hair?

A

Protection against external factors

Sebum: Secreted from associated sebaceous glands, lubricates and waterproofs the hair

Apocrine sweat

Thermoregulation

social and sexual interaction

Epithelial and melanocyte stem cells

133
Q

Where are the three regions of terminal hairs located?

A

Scalp, eyebrow, and eyelashes

134
Q

What type of hair is found on the rest of the body?

A

Vellus hair

135
Q

What are the three phases of the hair cycle (in order)?

A

Anagen
Catagen
Telogen

136
Q

What is the hair cycle?

A

Hair grows and is eventually shed, and subsequently replaced by new hair.

137
Q

What is in the anagen phase?

A

Hair growth and formation
Cells divide rapidly at the root of the hair, pushing the hair shaft up and out

Basal cells in the hair matrix produce new hair follicles, 85% of hair (2-7 years).

138
Q

What occurs during the catagen phase?

A

Regressing phase

Transition from the hair follicles active growth *2-3 weeks

139
Q

What occurs during the telegenic phase?

A

Resting phase: Hair follicle at rest, no new growth proceeds

140
Q

What forms the central core of hair?

A

Medulla

141
Q

What forms the layer of compressed keratinised cells around the medulla?

A

Cortex

142
Q

What forms the outer layer of hair?

A

Cuticle

143
Q

Where are pilosebaceous follicles and sweat glands located?

A

On the superficial layer of skin with the exception for palms and soles.
Capillary network connects the sebaceous glands to the systemic circulation

144
Q

What is a pilosebaceous unit?

A

Sebaceous gland, hair follicles, and the arrector pili muscle

145
Q

Which is the function of the arrectorr pili muscle?

A

Contracts in response to nerve signals, from the sympathetic nervous system, enabling the external hair shaft to be erected.

146
Q

What is the primary purpose for the contraction of arrestor pili muscles?

A

Entrap a layer of insulated air, essential for thermoregulatory mechanisms
Smooth muscles extends at angle between surface of dermis and point in follicle wall

147
Q

Where do holocrine sebaceous glands open up in?

A

Pilary canal –> in axillae

148
Q

Which sweat glands are hair follicles associated with?

A

Apocrine glands

149
Q

Where is the infundibulum located?

A

Uppermost portion of hair follicle –> opening of sebaceous gland to surface of skin.

150
Q

Where is the isthmus located?

A

Inferior region of hair follicle between opening of sebaceous gland and insertion of arrestor pili muscle

151
Q

What is located within the bulge of hair?

A

Segment of outer root sheath located at insertion of arrestor pili muscle
The bulge is the location of hair follicle stem cells

152
Q

What three concentric layers form the wall of hair follicle?

A

Internal root sheath
External root sheath
Glassy membrane

153
Q

What does the internal root sheath surround?

A

Surrounds the root of the growing hair; extend just up to the hair shaft
Cells derived from the basal cells of the hair matrix
Inner root guides and shapes hair

Encloses follicular dermal pailla

154
Q

The external root sheath is an extension of the ______ encloses the hair root:

A

Epidermis (infundibulum)

155
Q

Which cells form the use of the hair root?

A

Basal cells

156
Q

Describe the migration pattern to generate lower anagen hair follicle?

A

Downwards, entire hair bulb matrix, proliferate and undergo terminal differentiation to form hair shaft and inner root sheath

157
Q

What is the glassy membrane?

A

Thick, transparent connective tissue sheath covering the hair root, connecting it to the tissue of the dermis

158
Q

What is the hair bulb?

A

Lower most portions of hair follicle, includes follicular dermal papilla and hair matrix

159
Q

What is the nail bed?

A

Specialised structure of the epidermis, located distally on phalanges and toes.
Nail body is formed on the nail bed, and protects the distal fingers; extremities experiences maximum mechanical stress

160
Q

What is the nail plate?

A

Final product of proliferation and differentiation of nail matrix, keratinocytes

161
Q

Where does the nail plate emerge from?

A

Proximal nail fold above the bone of distal phalanx

162
Q

Where does the nail plate attach to?

A

Nail bed

163
Q

Where does the nail plate detach?

A

Hyponychium

164
Q

Where does the nail matrix reside?

A

Deep to the proximal nail fold above the bone of distal phalanx

165
Q

What is the nail matrix?

A

Keratinocyte differentiation –> Unnucleated and adherent, cytoplasm completely filled by hard keratins, in addition to comprising of melanocytes

166
Q

What structure does the nail matrix form?

A

Forms the nail plate

167
Q

Which proliferating cells form the nail plate?

A

Cells from the stratum basale

168
Q

Where does the nail body originally form from?

A

Nail root

169
Q

How is the nail body anchored ?

A

Lateral nail folds, overlaps the nail on the sides, assisting with anchoring the nail body

170
Q

Where does the nail fold meet?

A

Meets the proximal end of the nail body at the nail cuticle, the eponychium

171
Q

What is the term used to describe the thick layer of epithelium over the nail matrix?

A

Lunula

172
Q

What are the 5 main functions of nail?

A

Protection of underlying distal phalanx

Counter-pressure effect to pulp important for walking and tactile sensation

Increase dexterity/ manipulation of small objects

Enhances sensory discrimination

Facilitate scratching or grooming

173
Q

What type of immune disorder is psoriasis?

A

Chronic immune-mediated

Polygenic predisposition combined with environment triggers

174
Q

What are the clinical signs of psoriasis?

A

Demarcated, scaly, erythematous plaques

175
Q

What type of plaques form during psoriasis?

A

erythematous plaques

176
Q

What is the most common systemic manifestation of psoriasis?

A

Psoriatic arthritis

177
Q

What are the common sites of psoriasis?

A

Scalp, elbows, and knees

Followed by nails, hand, feet and trunk

178
Q

What is the pathophysiology of psoriasis?

A

Stressed keratinocytes release DNA/RNA

Forms complex with antimicrobial peptides

Induces cytokines (TNF-a, IL-1 and IFN)

Activates dermal dendritic cells (Langerhans cells in stratum spinosum)

179
Q

Where do dendritic cells migrate to?

A

Lymph nodes –> promotes TH1, Th17, th22 cells –> chemokine release - migration of inflammatory cells into dermis –> cytokine release –> keratinocytes proliferation –> psoriatic plaque

180
Q

Which type of psoriasis is marked with scaly erythematous plaques?

A

Extensor distribution

181
Q

What term is used to describe scaling under the nail plate due to excessive proliferation of keratinocytes in the nail ned and hyponychium?

A

Subungual hyperkeratosis

182
Q

What occurs during onycholysis?

A

Separation of nail plate from underlying nail bed and hyponychium
Distal plate discolours

183
Q

What occurs during pitting?

A

Sign of partial loss of cells from surface of nail plate, proximal nail matrix psoriasis

184
Q

What is erythroderma?

A

Reddening, flaking and thickening of skin

185
Q

What is guttate psoriasis?

A

illustrated as red, scaly, teardrop-shaped spots.

186
Q

Which Vitamin D analogs can be used to manage psoriasis?

A

Corticosteroids, retinoids (band dermatitis), topical tacrolimus

187
Q

Which types of phototherapy can be used to manage psoriasis?

A

Narrowband UVB, PUVA

188
Q

What is PUVA?

A

Psoralen and UVA

189
Q

Which types of systemic immunosuppressants are used to treat psoriasis?

A

Methorexate
Ciclosporin
Fumaric acid esters
Apremilast

190
Q

Which advantage therapies are used to manage psoriasis?

A

Anti-TNF
Anti-IL17
Anti-IL23
JAK inhibitors

191
Q

What is atopic eczema?

A

Pruritic chronic inflammatory condition
Complex genetic disease with environmental influences, associated with other atomic disorders
Not in contact with allergen

192
Q

What other disorders are associated with atopic eczema?

A

Asthma

Rhino-conjunctivitis

193
Q

Which areas of the body is acute inflammation associated with?

A

Cheeks, scalp and extensors in infants

194
Q

What type of inflammation is common in atopic eczema ?

A

Flexural inflammation

195
Q

What treatment is used to manage atopic eczema?

A

Emollients, and anti inflammatory therapy

196
Q

What are the common clinical features of atopic eczema?

A

Infantile phase atopic dermatitis: Erythematous, oedematous papule and plaques.

197
Q

What type of dermatitis is common due to allergens?

A

Allergic contact dermatitis

198
Q

What lifestyle management schemes can be used to treat eczema?

A

Emollients to prevent desiccation of skin
Omission of soap, topical application technique, day treatment, patch testing and biopsy

Clinical nurse specialist involvement : Habit reversal

199
Q

What are topical corticosteroids?

A

Correct potency for correct site, topical tacrolimus
Phototherapy
Retinoids
Systemic immunosuppression

Advanced therapies