DERM WEEK 1 Flashcards

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1
Q

Which component of skin?

  • outer layer
  • stratified cellular epithelium
  • contain keratinocytes (structural keratins)
  • recieves movement from basement membrane
  • contains four layers
A

epidermis

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2
Q

Which component of the skin?

  • formed from mesoderm below ectoderm
  • beneath epidermis
  • made up of connective tissue
  • less cellular
A

dermis

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3
Q

what cells produce pigment in the skin?

A

melanocytes

  • from neural crest (transient embryonic structure that gives rise to most of the peripheral nervous system)
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4
Q

what three layers are formed at 4 weeks of foetal skin development?

A
  • periderm
  • basal layer
  • dermis
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5
Q

what five layers are produced at 16 weeks? (final stage development)

  • (from inner to outer)
A
  • dermis
  • basal layer
  • prickle cell layer
  • granular layer
  • keratin layer
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6
Q

where are melanocytes loacted?

A
  • in the basal layer
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7
Q

what are blaschko’s lines?

A
  • development growth pattern of skin
  • lines become apparent when some diseases of skin or mucosa maifest themselves into these patterns
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8
Q

what five layers does the skin consist of?

A
  • epideris
  • appendages (nails, hair, glands, mucosae)
  • dermo-epidermal junction
  • dermis
  • sub-cutis
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9
Q

what is the sub-cutis?

A

predominantly fat

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10
Q

name three key cells in the epidermis

A
  • melanocytes
  • langerhans cells
  • merkel cells
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11
Q

name three body sites where the epidermis may vary

A
  • scalp
  • armpit
  • sole of foot
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12
Q

skin on palm

A
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13
Q

abdominal skin

A
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14
Q

scalp skin

A
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15
Q

what three factors control epidermal turnover?

A
  • growth factors
  • cell death
  • hormones
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16
Q

how many days does it take for the epidermis to regenerate?

A

28 days

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17
Q

where do keratinocytes migrate from?

A

basement membrane

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18
Q

purpose of keratinocytes?

A
  • preserve agains microbial, viral, fungal and parasitic invasion
  • protect against UV radiation
  • minimise heat, solute and water loss
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19
Q

what layer of the epidermis?

  • usually one cell thick
  • small cuboidal
  • lots of intermediate filaments (keratin)
  • highly metabolically active
A

basal layer

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20
Q

what epidermis layer?

  • large polyhedral cells
  • lots of desmosomes (connections)
  • intermediate filaments connect to the desmosomes
A

prickle cell layer

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21
Q

what layer of the epidermis?

  • 2-3 layers of flatter cells
  • large keratohyalin granules
    • contain filaggrin and involucrin
  • lamellar bodies
  • high lipid content
  • cell nuceli and organelles lost
A

granular layer

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22
Q

what layer in the epidermis?

  • overlapping non-nucleated cell remnants
  • insoluble cornified envelope
  • 80% keratin and filarggrin
  • lamellar granules release lipid
  • acts as a tight waterproof barrier
A

keratin layer

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23
Q

purpose of the teeth being keratinised?

A

to deal wtih friction/pressure

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24
Q

name some organs that are lined by mucosal membrane

A
  • eyes
  • mouth
  • nose
  • genito-urinary
  • Gi tracts
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25
Q

is the lining of mucosa keratinised or non-keratinised?

A

non-keratinised

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26
Q

what two functions do desmosomes allow for in the prickle cell layer?

A
  • adhesion
  • flexibility
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27
Q

defin a scar in terms of the epidermal layers affected?

A

a scar is defined as the appendages (nails, hair, glands, mucosae) no longer being present

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28
Q

what is the pilosebaceous unit?

A

between hair and grease producing gland (the two are always together)

  • important concept for acne
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29
Q

how does fillagrin play a role in water retention?

A
  1. fillagrin gets chopped (proteolyzed) by proteases
  2. the amino acid breakdown products contain a very important feature that RETAINS WATER
  3. they bind water molecules so they cant excape through the keratin layer
  • very important in regulating skin hydration
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30
Q

what types of cells make up the majority of the epidermis?

A

keratinocytes

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31
Q

three other types of cells in the epidermis apart from kertinocytes?

A
  • melanocytes
  • langerhans
  • merkel cells
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32
Q

what are these cells in the epidermis?

  • migrate from neural crest to the epidermis in he first 3 months of foetal development
  • located in the basal layer and above
  • pigemnt that produces dendritic cells
A

melanocytes

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33
Q

what are melanosomes?

A

organelles in melanocytes

  • transported to the tip and taken up be neighouring keratinocytes
  • melanin forms thicj brown coloured cap that will not let light penetrate
  • to naked eye would look like a mole or a brown hugh
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34
Q

what is the purpose of melanin forming a coloured cap in the basal cell layer?

A

to protect stem cells from UV radioation as light is not able to penetrate through

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35
Q

what drives the process of melanin granules forming the brown cap in the basal cell layer? (causing moles/ brown hughes)

A

Hormonally driven

  • alpha melanocyte hormone
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36
Q

what can trigger the alpha melanocyte stimulating hormone to carry out the transportation of melanocytes to basal cell layer?

A

UV radiation activates the tyrosinase pathway

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37
Q

what do melanocytes do to tyrosine?

A

convert tyrosine to melanin pigment

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38
Q

what cells are responsible for the transport of melanin pigment?

A

melanosomes

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39
Q

disorder in which the alpha melanocyte stimulating hormone is produced in excess by the pituatry?

= more melanin

A

nelson’s syndrome

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40
Q

what type of cell is this in the epidermis?

  • originates in the mesenchyme - bone marrow
  • prickle cell level in the epidermis
  • also found in dermis and lymph nodes
  • they detect microbes and are involved in skin immune system
  • pick up the antigen in skin and circulate it to lymph nodes via the lymphatic system
  • birbeck granules are present (tennis rackets)
A

langerhans cells

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41
Q

what type of cells are these in the epidermis?

  • basal layer
  • between keratinocytes and nerve fibres
  • mechanoreceptors (somatosensory receptors)
  • close to the skins surface near the nerve endings
  • can turn into a rare, dangerous type of tumour
A

merkel cells

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42
Q

what is another name for a hair follicle?

A

pilosubaceous unit

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43
Q

name two component structures that make up the hair follicle?

A
  • epidermal component
  • dermal papilla (finger like projection arranged into double row to increase surface area between dermis and epidermis)
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44
Q

what always comes next to a hair follicle?

A

subaeceous gland

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45
Q

how is hair pigmented?

A

via melanocytes above dermal papilla

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46
Q

what are the three phases of hair growth?

A
  1. anagen = gorwing
  2. categen = involuting (curl or curve)
  3. telogen = resting
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47
Q

what can influence hair growth?

A

hormonal influences

  • e.g. thyroxine, androgens
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48
Q

what may be a reason for hair loss?

A

immune system

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49
Q

what happens during the telogen phase of hair growth?

A

hair remains in follicle until it is pushed out by growth of new anagen hair

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50
Q

what is the growth rate of nails?

A

0.1mm per day

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51
Q

name the root of the nail

A

the nail matrix

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52
Q

what is the lenula?

A

keratin structure that looks like a half moon

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53
Q

what is the cuticle for?

A

protecting the nail against bacteria etc.

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54
Q

What is the dermo-epidermal junction?

A

interface bewteen the epidermis and dermis

  • underneath the basal cells
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55
Q

purpose of the demo-epidermal junction?

A
  • support
  • anchorage
  • adhesion
  • growth
  • differentiation of basal cells
  • semipermeable membrane that acts as barrier and filter
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56
Q

what cells are contained in the dermis?

A
  • fibroblasts (mainly)
  • macrophages
  • mast cells
  • lymphocytes
  • langerhans
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57
Q

type of fibres in the dermis?

A
  • collagen (90%)
  • elastin
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58
Q

other components that make up the dermis?

A
  • muscles
  • blood vessels
  • lymphatics
  • nerves
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59
Q

describe the flow of blood in the skin

A
  1. arteriole
  2. precapillary sphincters
  3. arterial venous capillaries
  4. post-capillary venules
  5. collecting venules
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60
Q

what type of plexuses are in the skins blood vessels?

A

horizontal plexus

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61
Q

what is a plexus?

A

branching network of vessels or nerves

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62
Q

what do lymphatic vessels in the skin drain?

A

continual drainage of…

  • plasma proteins
  • extravasated cells
  • excess interstitial fluid
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63
Q

role of lymphatic vessels in immune surveillance?

A
  • circulates lymphocytes and langerhans cells
  • channels micro-organisms/toxins
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64
Q

what are the nerve types in the epidermis + dermis?

A

somatic sensory

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65
Q

what nerve supply is present in the skin?

A

autonomic nerve supply

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66
Q

name the special receptors in the skin?

A
  • Pacinian corpuscles
  • Meissners corpuscles
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67
Q

receptors in the skin that can sense when theres pressure on it

A

pacinial corpuscles

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68
Q

nerve endings responsible for fine, discriminative touch and vibration sensations

A

Meissners corpuscles

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69
Q

what is the pilosubaceous unit?

A
  • epidermal component plus dermal papilla
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70
Q

what are the names for the three types of skin glands?

A
  • sebaceous
  • apocrine
  • eccrine
71
Q

What gland is this?

  • open into papillary canal
  • widely distributed
  • hormone sensitive: become more active produce more oil when puberty hits
  • helps hair fight against infection from fungal and control moisture loss
  • important for acne
A

sebaceous gland

72
Q

what gland is this?

  • real purpose isnt truly know
  • develop as part of the pilo-sebaceous unit
  • produce oily fluid
  • may produce odour after bacterial decomposition
  • cell lined
  • androgen dependent
A

apocrine sweat gland

73
Q

what gland is this?

  • sweat gland
  • triggered by ANS
  • react when you are hot, nervous, stressed etc.
  • help with thermoregulation, cool by evaporation
  • dilate when body is hot
  • present everywhere but especially in areas that get sweaty
  • sympathetic cholinergic nerve supply
  • help with filtration
A

eccrine glands

74
Q

4 functions of the skin?

A
  • barrier function
  • metabolism + detoxification
  • thermoregulation
  • immune defence
  • sensory function
75
Q

what two metabolism pathways is the skin involved in?

A
  • vitamin D metabolism
  • thyroid hormone metabolism
76
Q

Name the 4 factors in the skin that contribute to defense

A
  • structure
  • cell types
  • cytokines, chemokines, eicosanoids, antimicrobial peptides
  • genetics
77
Q

what parts of the structure of skin contribute to immunological defence?

A
  • keratin layer (stratum conreum)
  • stratification
78
Q

what are cytokines, chemokines, eicosanoids and antimicrobial peptides?

A

chemical signals that influence cell behaviour or help target pathogens

79
Q

where are T cells produced?

A

bone marrow

80
Q

where are T cells sensitised?

A

In the Thymus (in the neck)

81
Q

what two things does antigen recognition and T cell activation involve?

A

interaction with…

  • T cell receptor (TCR)
  • Major histocompatibility complex (MHC)
82
Q

what enhances Ag recognition and T cell activation interactions with TCR and MHC?

A
  • CD4+ helper cells
  • CD8+ cytotoxic T cells (CTL’s)
83
Q

what do TH1 activate?

A

macrophages to destroy microorganisms

84
Q

What do TH2 cells do?

A

help B cells to make antibiotics

85
Q

interleukin associated with TH1?

A

IL2, IFNg

86
Q

what interleukins are associated with TH2?

A
  • IL-4
  • IL-5
  • IL-6
87
Q

what are CD4+ cells?

A

helper T cells

88
Q

what are CD8+ cells?

A

cytotoxic T cells (CTL’s)

89
Q

purpose of CD8+ cytotoxic T cells?

A
  • can directly kill infected cells
  • important portection against viruses and cancer
90
Q

what should healthy skin contain?

A
  • t lymphocytes in both epidermis and dermis
91
Q

what type of T cells are found on the epidermis mainly?

A

mainly CD8 T cells

  • to kill microbes
92
Q

what types of T cells are found in the dermis?

A
  • CD4 AND CD8
93
Q

name another subset of T cell (other than CD4/CD8) that are found in the skin

A

NK cells (natural killer cells)

94
Q

what type of response are CD4 Th cells associated with?

A

inflammation

95
Q

what pathologies are CD4 Th cells associated with?

A
  • Psoriasis
  • atopic dermatitis (eczema)
96
Q

what pathology are TH1 cells related to?

A

psoriasis

97
Q

what pthology are TH2 cells related to?

A

atopic dermatitis (atopic eczema)

98
Q

what are dendritic cells?

A
  • tree like branches
  • initiate adaptive immune response
  • most potent type of antigen presenting cells
  • from bone marrow
99
Q

what are the two types of dendritic cells found in the dermis?

A
  • Dermal DC
  • Plasmacytoid DC
100
Q

what are dermal DC?

A
  • cells more like helper dendritic cells
  • involved in antigen presentation
  • secrete cytokines and chemokines
101
Q

what are plasmacytoid dendritic cells?

A
  • more aggressive than dermal DCs
  • produce interferon alpha (this notifies other cells to increase anti-viral defence)
102
Q

name the 3 other immune cells in the dermis other than dendritic cells?

A
  • macrophages
  • neutrophils
  • mast cells
103
Q

function of macrophages?

A
  • engulfs other cells to produce cell debris
104
Q

function of neutrophils?

A
  • circulating leukocytes
  • attracted to tissue by chemokines
  • make more chemkines and cytokines
  • are also phagocytic
105
Q

function of mast cells?

A
  • found in barriers
  • moderate IgE response
  • binding of IgE causes mast cell activation and release of inflammatory markers
  • phagocytotic cells
106
Q

what happens when keratinocytes in the epidermis are under stress?

A
  • release factors that stimulate plasmacytoid dendritic cells to produce IFNalpha
  • release IL-1/IL-6 and TNF
107
Q

what is the fundamental pathological process in psoriasis?

A

chronic inflammation

108
Q

what may cause psoriasis?

A
  • environmental factors with genetic susceptibitilty
109
Q

what TWO histological features must a patient have to have atopic eczema?

A
  1. BARRIER BREAK in the skin (fillargin)
  2. Overreactive immune response
110
Q

what are interleukins and interferons?

A

signalling molecules realeased by Th cells for an immune response

111
Q

when is an immune response launched?

  • name the important group of proteins involved in this process
A

when the cells cant recongise eachother through connecting via cell surface receptors

may be due to…

  • cancer cell
  • microbe
  • antigen
  • MHC protein is involved
112
Q

where do major histocompatibility complex proteins come from?

A

chromosome 6

113
Q

Describe type 1 MHC molecules

A
  • found on almost all cells
  • presents antigen to cytoxoic T cell
  • present human antigens to stop them from being killed
114
Q

describe type 2 MHC cells

A
  • found on antigen presenting cells i.e. B cells, dendritic cells and macrophages
  • present antigens to T helper cells
  • cell type presents exogenous cell material
115
Q

what is porphyria?

A
  • group of disorders that affect the production of heme
  • when heme synthesis is halted it causes the build up of one of its precursor molecules
116
Q

what are porphyrins essential for?

A

function of haemoglobin

  • protein in the red blood cell that links to porphyrin binds iron and carries oxygen to your organs and tissues
117
Q

what is fitzpatrick sun reactive skin phototypes

A

characteristic present at birth

  • people with photsensitivity may burn easily on exposure to sun
118
Q

Main types of grouped porphyrias?

A
  • erythropoietic protophyria (photoxic skin porphyrias)
  • blistering and fragile skin porphyrias
  • acute attack porphyrias (some have no skin involvement)
  • severe congenital porphyria (e.g. congenital erythopoietic porphyria)
  • porphyria cutanea tarda
119
Q

in what ways can the disease present itself?

A
  • acute neurovisceral
  • non-acute cutaneous
  • mixed
120
Q

where do the built up haem precursors end up?

A
  • faeces
  • urine
  • non-acute cutaneous
  • erythrocytes
121
Q

why do the heme precursors build up?

A

one of the enzymes in the heme pathway is deficient

122
Q

what causes blisters and skin fragility in porphyria?

A
  • caused by an accumulation of water soluble porphyria on skin surface that have been oxidised by free radicals or sunlight
123
Q

what are virulence factors?

A
  • enables a foreign microbe to be able o achieve colonisation of a host and enhance its potential to cause a disease
  • disease caused by specific component of pathogen e.g. toxin
  • toxic shock
  • strains, sub species, carrying different genes that influence pathology
  • can be interchanged with virulence
124
Q

which area of the body does staphylococcus tend to colonise?

A
  • sebaceous gland
    • e.g. front of the nose
125
Q

how can s.aureus infection progress so vastly?

  • e.g. go from superficial lesions to systemic to toxinoses
A

it has a wide number of different virulence factors they express, different proteins

126
Q

name the two main broad species of staphylococci that cause skin conditions?

A
  • staph epidermis
  • staph aureus
127
Q

what is a coagulase test?

A

whether something coagulases plasma

128
Q

name some virulence factors from staph. aureus

A
  • fibrinogen binding protein - adhesin
  • coagulase - clots plasma
  • leukocidin - inactivates leukocytes
  • TSST-1 (toxin) - shock, rash, desquamation
129
Q

what is an endotoxin?

A

toxin present inside a bacterial cell that is released when it disintegrates

130
Q

does staph. aureus test coagulase positive or negative?

A

coagulase positive

131
Q

what bacteria strain result is this?

  • common human pathogen
  • produces enzymes
  • flucloxacillin is primary treatment
  • grows best in aerobicly but can also grow anaerobically
A

staphyloccus aureus

132
Q

name the three strains of staph aureus that produce toxins

A
  • enterotoxin
  • staphylococca scalded skin syndrome toxin (SSST)
  • panton valentine leucocidin (PVL)
133
Q

strain of bacteria causes…

  • boils/carbuncles
  • cellulitis
  • infected psoriasis
  • impetigo
  • woud infections
  • SSST
  • PVL
  • 30% of hospital staff carry it
A

staph. aureus

134
Q

what makes staph aureus highly effective as a pathogen?

A

multiple virulence factors

135
Q

what is MRSA?

A
  • bacteria thats resistent to several widely used antibiotics
  • spread in the community
  • can be infected by things that have touched infected skin
136
Q

MRSA treatment options?

A
  • doxy
  • co-trimoxazole
  • clindamycin
  • vancomycin
137
Q

does staph. epidermidis test positive or negative for the coagulase test?

A

coagulase negative

138
Q

where does coagulase usually hang around in the bod for staohylococcus epidermidis?

A
  • skin
  • mucous membrane
  • often associated with prosthetics in the body, heart valves, knee replacements etc.
139
Q

when would infection usually occur for staphylococcus epidermidis?

A
  • usually in the immunocomprimised in hospital
  • associated with foreign objects e.g. catheters
140
Q

name 3 competitive skin commensals

A
  • staph. E
  • corynebacterium Sp.
  • Propionbacterium Sp.
141
Q

what is this?

  • positive coagulase cocci
  • causes UTI in women of child bearing age
  • novobiocin resistent (all other staph are sensitive)
A

staph saprophyticus

142
Q

what is this?

  • cocci in chains alpha haemolytic
  • pathogen most common cause of pneumonia
A

strep pneumoniae

143
Q

what is this?

  • cocci in chains alpha haemolytic
  • commensla bacteria of mouth, throat and vagina
  • can cause infective endocarditis
A

strep viridans

144
Q
  • gut commensals that are not haemolytic
  • inhabits Gi tract
  • gram positive
A

enterococcus species

145
Q
  • gram positive cocci in chains
  • classified by beta haemolysis
  • infected eczema
  • impetigo
  • cellulitis
  • erysipela
  • necrotising fascitis
A

streptococcus pyogenes

146
Q

how is streptococcus pyogenes treated?

A

penicillin

(also flucloxacillin)

147
Q

how to test a boil of a furuncle?

A
  • swab if lesion is broken
  • if its a depper lesion take a tissue or pus sample
  • blood culture if appropriate
148
Q
  • rare condition
  • caused by an out of proportion massive immune system release of cytokines etc.
  • antigen binds appropriatle and activates 1 in 5 T cells (incredibly high)
A

toxic shock syndrome

149
Q

symptoms and warning signs of toxic shock syndrome?

A
  • fever (over 39 degrees)
  • diffuse macular rash and desquamation
  • hypotension (less than 90 systolic)
  • greater than 3 organ systems involved
150
Q
  • bacterial infection along fascial planes below skin surface
  • rapid tissue destruction
  • life threatening soft tissue disease
  • characterised by rapidly progressive necrosis that spreads in subcutaneous tissue into deep fascia
  • 25% mortality rate
A

necrotising fascitis

151
Q

what is necrotising fascitis secondary to?

A
  • organ failure and
  • streptococcal toxic shock syndrome
152
Q

Name 7 basic tissue groups found in the skin

A
  • epithelium
  • glands
  • muscle
  • hair
  • adipose (fatty) tissue
  • connetive tissue
  • nervous tissue
    • nails
153
Q

where may there be more undulations in the epidermis?

A

ridges and grooves of fingerprints for example

154
Q

what are these glands stained in purple?

A

sebaceous glands

  • produce sebum (oily film on nose and forehead skin)
155
Q

what are these glands?

A

sebaceous glands

156
Q

what glands are found over whole bodyd except lips and genitals

  • regulate heat and salt loss
A

eccrine glands

157
Q

what glands?

  • limited to axillae/nipple/genitals
  • develop at puberty and open into hair follicles
A

apocrine glands

158
Q

smooth muscle fibres attached to hair follicles that help with hair standing on end?

  • also present in walls of blood vessels
A

arrector pili

159
Q

what are free nerve endings for?

A

to sense pain

located in basal layer of epidermis

160
Q

what is located at the base of the hair follicle?

A

Hair bulb contains…

  • hair matrix
  • dermal papilla
161
Q

where is soft and hard keratin located in the hair?

A
  • SOFT: central medulla
  • HARD: outer cortex and cuticle
162
Q

where is the nail matrix located?

A

base of nail

163
Q

purpose of the hyponychium?

A

secures the free nail edge

164
Q

implications of skin failure?

A
  • loss of thermoregulation (may contribute to cardiovascular instability)
  • increased risk of infection
  • failure of homeostatic function (fluid and electrolyte losses)
165
Q

what is fibroplasia?

A

fibroblasts lay down matrix and contract the wound

166
Q

what is angiogenesis?

A

endothelial cells develop into new blood vessels

167
Q

what layer of th skin do first degree burns reach?

A

epidermis only

168
Q

what layer of skin do second degree burns reach?

A

epidermis and dermis

169
Q

what layer of skin do third degree/ full thickness burns reach?

A

extends beyond dermis

170
Q

what is surface slough?

A

mixture of dead cells, polymorphs and bacteria

  • yellow/green in colour
  • may be quite adherent to underlying tissue
  • has inhibitory affects on the healing ability of the wound
  • should be removed chemically or with physical debridement (larval therapy can also be used)
171
Q

three stages of wound healing?

A
  1. inflammation
  2. proliferation
  3. tissue remodelling
172
Q

why is primary intention wound healing more rapid than secondary?

A

wound edges are opposed so less of a defect to heal

173
Q
A