1 Flashcards
epidermis and dermis come from where in embryo
ectoderm
melanocytes come from where in embryo
neural crest
2 types of melanin pigment
phaemelanin (red, yellow)
eumelanin (brown, black)
melanin is made from
tyrosine
layers of skin from most deep to superficial
dermis > basal layer > prickle layer > granular layer > keratin layer
epidermis is made up of
90% keratinocytes
how many layers in epidermis
4
what cells are found in epidermis
melanocytes
langerhans
merkel cells
how many days for keratinocytes to migrate from basement to top
28 days
basal layer facts (3)
highly metabolic
single layer
cuboidal
prickle cell layer features (3)
large polyhedral cells
desmosomes
intermediate filaments
which layers has no nuclei
granular and keratin
which layer has odland bodies (lamellar bodies)
granular
granular layer has which features (5)
flatter cells large ketatohyaline granules (containg filagrin) odland bodies high lipid content nuclei lost
cells in keratin layer
corneocytes
keratin layer made up of what components
80% keratin and filaggrin
condition where too much melanin producing hormone by pituitary
nelsons syndrome
where will you find langerhan cells
prickle later
dermis
lymph nodes
langerhan cells have organelle called ____ that looks like a _____
birbeck granule, looks like tennis racket
merkel cell is
mechanoreceptor found between keratinocytes and nerve fibres
what can trigger merkel cell cancer
virus
phases of hair growth
anagen = growing catagen = involution (groth stops/resting begins) telogen = resting
nails are made up of
keratin
parts of nail
top: cuticle > lunula > nail plate
under: matrix > nail bed > hyponchium
acquired (autoimmune) diseases that affect dermo-epidermal junction (3)
Bullous pemphighigouS (s-for shallow) Bullous pemphigoiD (d-deep) dermatitis herpetiformis
what can be found in dermis (8)
fibroblasts macrophages mast cell langerhans lymphocytes ground substances blood vessel nerves
buzzword: port wine stain
angioma
what is an angioma
benign tumour derived from vascular or lymphatic vessels
pacinian receptor senses
pressure (P for pressure) in dermis
meissners receptor senses
vibration (in sub-cutaneous)
3 types of skin glands
sebaceous
eccrine
apocrine
sebaceous gland does what
prevents moisture loss, produces sebum, anti-microbial
eccrine does what
cooling
apocrine does what
scent
apocrine glands are found where
axilla and perineum
eccrine glands found where
all over body
sebaceous glands found where
everywhere but palms of hands and soles of feet
what 2 things get metabolised in skin
vit D and thyroid hormone (T4>T3)
Buzzword: cafe au lait macules and axillary or inguinal freckles
neurofibromatosis
Buzzword: ash-leaf macule under woods lamp
tuberous sclerosis
4 genetic skin diseases
tuberous sclerosis
neurofibromatosis type 1 (most common)
atopic eczema
epidermolysis bullosa
what if defective in atopic aczema
filagrin (skin barrier gene)
types of epidermolysis bullosa (EB) (3)
simplex (epidermal)
junctional (DEJ)
dystropic (dermis)
keratin layer is also called
stratum corneum
what forms keratin layer
differentiation of keratinocytes > corneocytes
type of T cell found in epidermis
CD8+
type of T cell found in dermis
both CD8+ and CD4+
Th1 response associated with
psoriasis
Th2 response associated with
atopic dermatitis
Th17 response associated with
both psoriasis and atopic dermatitis
Th2 response involves what immune components
b cells
IL4
IL5
IL16
Th1 response involves what immune components
macrophages
IL2
IFN gamma
types of dendritic cells found in dermis
dermal DCs
plasmocytoid DCs
plasmocytoid DCs produce
IFN gamma
which skin conditions are due to type 4 hypersensitivity
tuberculin reaction (skin test) contact dermatitis
**takes 24-48hrs
which skin feature are due to type 1 hypersensitivity
wheel and flare (rapid)
cellular infiltrate or nodule (late)
allergic contact dermatitis due to
multiple sub-threshold exposures to allergen (called afferentor sensitising stage, leading to efferent phase)
treatment for allergic contact dermatits
avoidance
topical steroids
oral antihistamine
autoimmune skin conditions
psoriasis
vitiligo
SLE
what is koebner phenomenon
skin lesions appearing in lines of trauma
which conditions show the koebner phenomenon
psoriasis
vitiligo
SLE * the autoimmune ones*
T cells mediate autoimmune skin conditions (psoriasis, vitiligo, SLE) by secreting what
IL17A
IL17F
IL22
these all cause keratin cell proliferation
impedin allows pathogen to
avoid host defences
aggressin allows pathogen to
cause damage directly
modulin allows pathogen to
cause damage indirecty
cytotoxin associated with S.aureus virulence
panton-valentine leukocin (PVL)
PVL is toxic to
leucocytes
what causes necrotising pneumonia
CA-MRSA - community associated MRSA
what causes gas gangrene
?? clostridium perfringens
group A strep
B-haemolysis (strep pyogenes)
B-haemolysis (strep pyogenes) can cause
cellulitis
impetigo
nec fasciitis
epidermis made up of which layers
stratum corneum (20 cells deep) stratum lucidum (only palms/soles) stratum granulosum (lose nuclei) stratum spinosum stratum basale
atopic treatments in order of thinnest to thickest consistency
lotions>creams>ointments>gels> pastes>powders
what is secreted by kertinocytes to make waterproof barrier
reticular bodies
steroid pathway
diffuses (because lipophilic) > bind receptors in cytoplasm > conformational change exposing DNA-binding site > receptor+steroid complex moves to nucleus and binds steroid response element in DNA > transcription of specific genes either switched on or off
number of skin conditions known
2000
what % of GP appointments for skin
19%
when in gestation do sweat glands develop
6 months
nuclei loss starts and finishes where
starts granular layer, finishes keratin layer
granular layer is ___ cells thick
3
what is only found in DEJ
hemidesmosomes
what is most common sweat gland on face
eccrine
creams are
oil in water - preservatives
ointments contain
paraffin - no preservatives
where will you use a cream
hair bearing area
lotions contain
alcohol
roles of steroids
vasoconstriction
anti-inflam
anti-proliferative
steroids: most mild is
hydrocortisone (1%)
what do you use topical steroids to treat
eczema (dermatitis)
psoriasis
non-infective anti inflam issues
keloid scars
how much topical steroid/cream etc to cover whole body
20-30g
one finger tip is how much topical steroid
half gram = covers 2 hand areas
side effects of steroids (6)
- thinning of skin
- purpura (red/purple that does not blanche - bleeding under skin)
- stretch marks
- rosacea
- telangiectasia
- periorbital dermatitis (around mouth)
treatment for acne
clindamycin
erythromycin
tetracycline