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DermJaz > Physiology > Flashcards

Physiology Flashcards

1
Q

Embryologically the epidermis comes from the ____derm

A

Ectoderm

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2
Q

Embryologically the dermis comes from the ____derm

A

Mesoderm

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3
Q

Embryologically melanocytes comes from ______

A

Neural crest cells

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4
Q

The skin is fully developed at wk __ gestation

A

Week 26

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5
Q

At 4wks gestation the components of the skin are :

A

Periderm, basal layer, dermis (corium)

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6
Q

At 16wks gestation the ____ migrate from ____ and the layers of the skin =

A

Melanocytes migrate from the neural crest

Keratin, granular, prickle cell, basal and dermis

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7
Q

The epidermis is ________ epithelium.

A

Stratified squamous

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8
Q

____ make up 95% of the epidermis

A

Keratinocytes

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9
Q

The prickles in the prickle cell layer are _____

A

Lots of desmosomes

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10
Q

The basal cell layer is ____ for rigidity

A

Undulating

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11
Q

Takes keratinocytes ____ to get from basement membrane until they are shed from the keratin layer

A

28 days normally

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12
Q

Basal cell layer : usually ____ thick
Shape of cells = ________
Contains lots of _______

A

1 cell thick
Small cuboidal cells
Lots of Intermediate filaments (keratin)

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13
Q

Prickle cell layer: shape of cells =

Lots of _____ connecting to _____

A

Larger polyhedral cells

Lots of desmosomes connecting to intermediate filaments

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14
Q

Granular layer: ____ layers of cells = thin/thick layer
Shape of cells =
Contain ___ granules which contain ___ + _____
____ secreted from keratinocytes release _____ => high ____ content
Origin of ____ and _____ are lost here

A

2-3 layers - thin layer
Flattened cells
Keratinohyalin granules contains structural filaggrin and involucrin proteins
Lamellar/Odland bodies release lipids => high lipid content
Cornified envelope origin, cell nuclei lost

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15
Q

Keratin layer- composed of ____ that overlap and have no ____
Other name =
80% ____+____
___ from ____ glues keratin together

A

Corneocytes with no nuclei
Cornified envelope
80% keratin and filaggrin
Lamellar bodies produce FAs

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16
Q

The cells that make up the epidermis =

A

Keratinocytes (95%) melanocytes ( basal and suprabasal) langerhans (suprabasal) merkel cells (basal)

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17
Q

Melanocytes are present in _____ layers

A

Basal layer and above

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18
Q

Melanocytes are ____ cells that produce _____

A

Dendritic cells

UV protection pigment

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19
Q

Melanocytes - organelle that is transferred via dendrites to adjacent keratinocytes, synthesise store and transport _____

A

Melanosomes

Melanin

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20
Q

Melanocytes convert ____ to _____

A

Tyrosine to melanin

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21
Q

Melanin comes in two forms ____ and ____ (give the colour of pigmentation they each give to skin)

A

Eu (brown/black)

Phaeo ( yellow/red)

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22
Q

Melanin forms a cap over the nucleus to protect ___ in the ____ cells and stopping it ___

A

Protects DNA in basal cells and stops it crosslinking

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23
Q

Langerhans originate from ____

A

Mesenchyme - from bone marrow

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24
Q

Langerhans cells are found in the ___ layer, ___ and ____

A

Prickle cell layer, dermis and lymph nodes

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25
Q

Function of Langerhans cells in the skin

A

APCs - take antigens from skin to lymph nodes- dendritic cells

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26
Q

Only cells to contain birbeck granules (racquet shaped)

A

Langerhans cells

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27
Q

Lamellar bodies are ___ shaped

A

Racquet

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28
Q

Merkel cells are found in ____ layer between ___ and _____

Function =

A

Basal cell layer between keratinocytes and nerve fibres

Mechanoreceptors

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29
Q

Pigmentation in pilosebaceous is due to ____ above the ____

A

Melanocytes above dermal papilla

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30
Q

90% of hairs are in this phase of growth

It takes ____

A

Anagen - growing phase

3-7 years

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31
Q

10% of hairs are in this phase of growth

Takes _____

A

Catagen - involuting

3-4 wks

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32
Q

<1% of hairs are in this phase of growth

Occurs in____ hairs per day

A

Telogen

Resting/ shedding - 50-100 hairs a day

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33
Q

Hair and nails are both composed of ____

A

Specialised keratin

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34
Q

Underneath nail plate lies ___ proximally and _____ distally

A 
Nail matrix proximally ( similar to hair bulb)
Nail bed (CT)
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35
Q

Functions of DEJ

A

Epithelial-mesenchymal interactions - support, anchorage, adhesion, growth and differentiation of epidermal cells
Semi permeable membrane

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36
Q

Contents of the dermis

A

Collagen, elastin, ground substance, blood vessels, lymphatics, nerves, cells

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37
Q

Cells found in the dermis

A

Mostly fibroblasts (=>collagen) macrophages, mast cells, lymphocytes, Langerhans

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38
Q

Ground substance in dermis is composed of

A

Mucopolysaccharides and glycosaminoglycans

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39
Q

Blood vessels in dermis - supply is > than metabolic needs

Organised in ______ that ____and don’t/do enter the epidermis

A

Supply > metabolic needs

Horizontal plexuses branch up and stop at DEJ along with lymphatics

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40
Q

Pressure sensors deep in dermis

A

Pacinian corpuscles

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41
Q

Very sensitive vibration sensors in superficial dermis

A

Meissners corpuscles

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42
Q

3 types of skin glands

A

Sebaceous
Apocrine sweat
Eccrine sweat

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43
Q

Skin glands that are hormone sensitive and cause acne if blocked

A

Sebaceous

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44
Q

Sebaceous glands are _____ distributed. Largest are found on __,___+___

A

Widely distributed

Face back chest

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45
Q

Function of sebaceous glands

A

Control moisture loss

Bacterial and fungal infection protection

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46
Q

Skin glands that produce sebum and mainly open up onto hair follicles

47
Q

Components of sebum

A

Squalene, wax esters, triglycerides, FFAs

48
Q

Skin glands that are part of the pilosebaceous unit and found in axils and perineum

A

Apocrine sweat glands

49
Q

Androgen dependent glands that secrete oily fluid (odorous after bacterial decomposition)

A

Apocrine sweat gland

50
Q

Locations of eccrine sweat glands

A

Whole skin surface - especially palms, soles and axillae

51
Q

Eccrine sweat glands have a ___ nerve supply

Stimulated by __,___+___

A

Sympathetic cholinergic

Mental, thermal and gustatory stimulation

52
Q

sebaceous glands are ___ distributed and are largest on the __+__+__

A

widely distributed

face, back and chest

53
Q

skin glands that produce sebum

they mainly open onto _____

A

sebaceous

hair follicle

54
Q

functions of sebaceous glands

A

control moisture loss

bac and fungal infection protection

55
Q

skin gland that is part of pilosebaceous unit and found in axillae and perineum

A

apocrine sweat glands

56
Q

sebum components =

A

squalene, wax esters, triglycerides, FFAs

57
Q

apocrine sweat glands are ____ dependent

they produce ___ that becomes odourous after ___

A

androgen dependent
oily fluid
bacterial decomposition

58
Q

skin glands that cover the whole skin surface especially palms, soles and axillae

A

eccrine sweat glands

59
Q

eccrine sweat glands have a ____ nerve supply - stimulated by ___+___+___

A

sympathetic cholinergic

mental, thermal ad gustatory stimulation

60
Q

functions of eccrine sweat glands = (3)

A

ultrafiltration (NaCl-HCO3 into hypotonic fluid)
cooling by evaporation
palms and sole grip

61
Q

2 metabolic functions of the skin

A

converts cholecalciferol to vit D3 (290-320nm UV)

T4 to T3 conversion

62
Q

Immunological functions of keratinocytes in keratin layer (3) =

A

sense pathogens and mediate response eg. UV/allergens
produce AMPs and directly kill
produce cytokines and chemokines to recruit and reg immune cells

63
Q

epidermis contains mainly ___ T cells
dermis contains ____ T cells
___ also present

A

epidermis = CD8+
dermis = CD4+ and 8+
NK also present

64
Q

Th1 cells activate ___ and produce __+__

A

macrophages

IL2 and IFNgamma

65
Q

Th2 cells produce ++_ and help ___ make ___

A

IL4+5+6

B cells make Ig

66
Q

CD4+ cells ass with inflammation ___ (psoriasis) ___ (atopic dermatitis) ___ (both)

A

Th1
Th2
Th17

67
Q

immunological cells in the epidermis

A

keratinocytes, langerhans, T cells

68
Q

immunological cells in the dermis

A

dendritic cells, mast cells, macrophages, neutrophils

69
Q

MHC I is present in ___ cells and present __to ___

A

most cells

endogenous antigens to CD8+

70
Q

MHC II is present in ___ cells and present ___ to ___

A

APCs

exogenous antigens to CD4+

71
Q

Scale that gives categories of skin tones and tanning patterns
Type __ to __

A

Fitzpatrick scale

I to VI

72
Q

part of dermis that is thin and just below epidermis

A

papillary dermis

73
Q

part of dermis that has thicker bundles of type I collagen with sweat glands and pilosebaceous units

A

reticular dermis

74
Q

ECM of dermis is composed of

A

hyaluronic acid and chondroitin sulfate

75
Q

components of the dermis

A

type 1+2 collagen matrix
elastic fibres
ECM

76
Q

persistance of nuclei in keratin layer =

A

parakeratosis

77
Q

parakeratosis is present in psoriasis where there is ___

A

high cell turnover

78
Q

acanthosis =

A

increased thickness of epidermis

79
Q

papillomatosis =

A

irregular epidermal thickening

80
Q

spongiosis =

A

oedema fluid between squames appears to increase prominence of intercellular prickles

81
Q

chemicals in skin that mediate itch

A 
histamine
PGE2
ACh
serotonin
IL2
kallikrein
substance P
82
Q

nerve transmission of itch in skin is by

A

unmyelinated C fibres

83
Q

mediators in the CNS for itch

A

opiates (endo+exogenous)

84
Q

orange naevi that if irritated causes a wheal =

A

mast cell naevi

85
Q

something usually inflam/dryness in skin triggers itch = ___ cause of itch
eg.s (4)

A 
pruritoceptive
asteatotic eczema
insect bites
lichen planus (sometimes ass with hep C)
psoriasis
86
Q

basis of cause of itch in asteatotic eczema

A

direct exposure of unmyelinated C fibres in bases of microfissures and inflammatory mediators in skin released

87
Q

type of eczema that is very xerototic => crazy paving/chicken wiring

A

eczema craquele

88
Q

4 types of causes of itch

A

pruritoceptive
neuropathic
neurogenic
pyschogenic

89
Q

basis of itch in neuropathic itch

A

damage of any sort to central/peripheral nerves that causes itch

90
Q

basis of itch in neurogenic itch

A

no evident damage in CNS but caused by something affecting the CNS receptors

91
Q

examples of causes of neurogenic itch

A

haematological, paraneoplastic, opiates, kidneys (endogenous opiates), hyperthyroid, PBC

92
Q

non specific anti pruritics =

A 
sedative antihistamines
emollients
antidepressants (doxepin)
phototherapy
opiate antagonists
ondansetron
anti-epileptics for some neuropathic ones
93
Q

cells in the skin that metabolise vitamin D

A

keratinocytes

94
Q

growth development of skin follows

A

Blaschko’s lines

95
Q

maceration =

A

softening and break down of skin due to prolonged moisture exposure

96
Q 
erythropoeitic protoporphyria = lack of \_\_ leading to \_\_ build up
presents at\_\_ (age) with \_\_
A

ferrochelatase
protoporphyrin IX
early childhood
discomfort, itch/tingling in sun

97
Q

most common sweat gland on the face =

98
Q

acute intermittent porphyria is due to the reduced function of ___ leads to ___ in many tissues

A

porphobilinogen deaminase

acute neurotoxic reaction

99
Q

Odland bodies are found in which epidermal layer

100
Q

it takes ___ days for cells to migrate from basal to keratin layer

101
Q

Pressure sensation corpuscles

102
Q

Vibration sensation corpuscles

A

Meissner’s

103
Q

tuberous sclerosis mode of inheritance =

104
Q

type 1-4 HPV =

105
Q

type 16 + 18 HPV =

A

cervical cancer

106
Q

type 6 and 11 HPV =

A

genital warts

107
Q

__ more likely than ointments to cause contact sensitisation

108
Q

___g of ointment for overall coverage

A

roughly 30g

109
Q

medial/lateral malleolus ulcers are likely to be __ in origin

110
Q

cancer that can develop on skin ulcers

A

squamous cell ca

111
Q

Breslow thickness =

A

depth from granular layer to deepest melanoma cell

112
Q

SCALP layers =

A 
Skin 
CT
Aponeurosis
Loose CT
Periosteum
113
Q

sebaceous cyst has an obvious ___ on examination

DermJaz (9 decks)

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