Intro to Derm Flashcards
Skin disorders are the _____ most common reason for visiting the doctor
first
Top 3 Global burden skin disease?
Dermatitis
Acne
Psoriasis
Weight skin
Size
4 kg
2 m^2
Where do hair follicles originate?
sub-cu
5 layers of epidermis?
stratum corneum stratum granulosum stratum spinosum stratum lucidum stratum basalis
filaggrin -
filament associated protein that binds keratin fibers in epithelial cells - found in the stratum granulosum
desmosomes layer
stratum spinosum
stem cell layer
stratum basalis
cycle from SB to SC
28 days
kertinohyalin granules
found in the stratum granulosum - contain pro-filaggrin
Fitzpatrick skin type
hair: blond/red
eye: blue/green
skin: fair
freckles: ++
sunburn: easily
tan: minimally
II
Fitzpatrick skin type
hair: blond/red
eyes: blue/grenn
skin: white
freckels: +++
sunburn: always
tan: never
I
Fitzpatrick skin type
hair: brown
eyes: dark
skin: moderate brown
freckles: 0
sunburn: minimally
tan: well
IV
Fitzpatrick skin type:
hair: brown
eyes: medium to dark
skin: light brown
freckles: +
sunburn: initially
tan: gradually
III
Fitzpatrick skin type:
hair: dark
eyes: dark
skin: black
freckels: 0
sunurn: never
tan: always
VI
Fitzpatrick skin type
hair: dark
eyes: dark
skin: dark brown
freckels: 0
sunburn: rarely
tan: dark tan
V
Skin color variation due to (2)
type of melanin
disbtribution of melanosomes
eumelanin
black to brown pigment
pheomelanin
mutated melanin - yellow to red pigment
light skin melanosome distribution -
clusters above nucleus
dark skin melanosome distribution?
individually throughout cytoplasm
fx
physical barrier
epidermis keritoncytes
fx
light barrier
epidermis melanocyte
fx
immunological barrier
epidermis
langerhaans cells
fx
vit D synthesis?
epidermis
keratinocytes
fx
water homeostasis
epidermis
keratinocytes
adnexa
eccrine glands
fx
grasp
adnexa
nails
fx
lubrication
adnex
sebaceous glands
fx
phermones
adnexa
apocrine glands
fx
thermoregulation
adnexa
eccrine glands
dermis
blood vessels
fx
strength and elasticity
dermis
fibroblasts (produce collagen and elastin)
fx
sensation
dermis
nerves
fx
insulation
sub-cu
fat
fx
calorie reservoir
sub cu
fat
epidermis composition
stratified squamous epithelium
dermis composition
underlying CT layer
papillary dermis
reticular dermis
papillary dermis
loose CT lies immediately under epi
reticular dermis
dense CT
Adnexal structures (5)
apocrine eccrine hair nails sebaceous
sub-cu composition
adipocytes
regional variation of skin
thick skin is…
hairless and found on the palms and soles
vitD synthesis
skin?
7-dehydroholesterol can be converted to vitD3 by UVB… but you can also ingest and absorb
What happens to VitD3 D2?
Converted to 25hydroxy D in liver
what happens to 25hydroxy D?
converted to 1,25 dihydroxy D in the kideny
keritinocyte fx
form barrier layer
kertinocyte synthesize
keratin
what is keratin
the major intracellular fibrous protein of the skin
keratinocyte cycle?
defined cylce of proliferation, differenatiation, and apoptosis (28 days)
melanocyte - fx and derivation
pigment producing cells arising from the neural crest
melanocyte location
primarily in the basal layer of the epidermis - in hair follicles
melanocyte - ration to keritinocyte -
1 : 10
how many kertinocytes does 1 melanocyte supply melanin to? via dendrites
30
what is melanin from
tyrosine
melanin is packaged into granules called
melanosomes
how are melanosome transferred to keratinocytes?
via dendritic processes of the melanosome
what does melanin do for us
protects basal keratinocytes from UV damage (DNA)
Absence of melanocytes is often due to?
autoimmunity causes vitiligo which cinlically consists of depigmented macules and patches
langerhaans cells - location
found in all epidermal layers
what are langerhaans cells?
dendritic cells in the epidermis derived from a bone marrow cell
What do langerhaans cells do?
participate in cell mediated immune reactions by processing and presenting antigens (circulate back and forth between skin and lymph nodes)
Stratum basalis =
basal cell layer
Stratum basalis - architecture
consists of single cell layer of cuboidal or columnar kertinocytes
_________ are the stem cells of the epidermis
basal kertinocytes - thus a site of intense prolifearation
hemidesmosomes
attach basal cells firmly to the basal lamina of the dermal epidermal juctnion
antibodies to the protein in the hemidesmosomes may cause autoimmune blistering diseases such as?
bullous pemphigoid
genetic defects in collagen VII cause?
dystrophic epidermolysis bullosa
Type VII collagen
type VII collagen fibril, composed of three identical alpha collagen chains, is restricted to the basement zone beneath stratified squamous epithelia. It functions as an anchoring fibril between the external epithelia and the underlying stroma. Mutations in this gene are associated with all forms of dystrophic epidermolysis bullosa
Laminin-5 genetic defects –>
Junctional epidermolysis bullosa
Laminin 5
Laminin, alpha 5 has been shown to interact with BCAM,[3][4] FBLN2[5] and Collagen, type VII, alpha 1.[6]
Important in hemidesmasome
Desmosome
attach kertinocytes to each other
antibodies to proteins in desmosomes may cause autoimmune blistering diseases such as
pemphigus vulgaris
congenital defects in keratin filaments 5 and 14 cause?
epidermolysis bullosa simplex
tonofilaments
protein structures (kertain filaments) that insert into the dense plaques of desmosomes on the cytoplasmic side of the plasma membrane
______________ has a prickly or spiny appearance due to desmosome attachment between cells
stratum spinosum
intercellular adhesion in the SS depends on _________-____________ interaction in the distribtuion of stress
tonofilament - desmosome
synthesis of involucrin and membrane coating granules begins in this layer
SS
Involucrin
In binding the protein loricrin, involucrin contributes to the formation of a cell envelope that protects corneocytes in the skin.
stratum granulosom
the cells of this layer contain different types of granules (below SS and above SL)
Keratinohyalin granules contain
Profilaggrin - found in SG
Filaggrin
cross links keratin tonofilaments and is important in the barrier function of the skin.
Filaggrin is mutated in dry skin conditions including (2)
ichthyosis and atopic dermatitis
which protein is mutated in atopic dermatitis
filaggrin
which protein is mutated in ichthyosis
filaggrin
stratum lucidum
only in thick skin
cells of this layer no longer have nuclei or organelles
above SG below SC
Stratum corneum
the outermost layer of the epidermis
kertinocytes have lost their nuclei and organelles and the entire cell is filled with keratin
desmosomes still connect tightly packed adjacent cells
papillary layer of dermis
site of
contains
site of attachment to the epidermis and necessary to its development and differentiation
contains capillary network that is blood supply for dermis
pathway for defense cells
contains meissner corpuscles which sense touch
reticular layer of dermis
composition
contains extensive collagen and elastin fibers that provide strength and flexibility
reticular layer of dermis
houses
houses (along with hypodermis) epidermal derivatives such as glands and hairs and plays a major role in their development and functioning
which layer of the skin is pathway for major blood vessels arranged specifically to facilitate thermoregulation?
reticular layer of dermis
which layer of the skin is the site of nerve tracts and major sensory receptors?
reticular
which layer of the skin are meissner corpuscles located
papillary
which layer of the skin are pacinian corpuscles located
reticular
sense vibration / pressure / touch
meissner corpuscles
job
location
composition
detect delicate touch
are most commonly found in the dermal papillae of thick skin
consist of Schwann cells and sensory nerve terminals wrapped by fibroblasts and collagen
Pacinian corpuscles
job
location
composition
rapidly adapting receptors that detect change in deep pressure
found in dermis of both thin and thick skin
large structures resembling onion
the concentric layers are composed of flattened CT like cells interspersed with intercellular fluid and collagen
a single sensory nerve fiber terminates within pacinian corpuscle
apocrine sweat glands
fx location
fx
specialized sweat glands located in axillary, pubic and perianal regions
produce a milky, viscid, carbohydrate rich secretion that is initally odorless; subsequent bacterial actions lead to a characteristic axillary body odor
when do apocrine glands fx
puberty
apocrine ducts empty where?
into hair follicles just above sebaceous glands
eccrine sweat glands
local
fx
traditional sweat glands distributed over most of the body
not found in lips, under the nails, or the glans penis, glans clitoris, or labia minoa
watery enzyme rich secretion initally isotonic becomes hypotonic as Na is reabsorbed
important for thermoregulation
hair
when develop?
develops in utero with down growth of the epidermis forming a pilosebaceous unit
hair composition
central medulla of soft keratin and cortex of hard keratin
hair growth
growth period is intermittent
2-3 year growth followed by a rest period of several months
hair pigment
comes from melanocytes at the base of the hair
goose bumps?
due to contraction of the arrector pilli
sebaceous glands
oil glands which secrete sebum, a complex mixture of lipids
sebaceous glands develop with?
with the hair follicles and empty their secretions into the upper 1/3 of the hair follicles
sebaceous gland is accelerated at
puberty
sebum
secreted from sebaceous glands (complex mixture of lipids)
kertohyalin granules
found in SG
Contain profilaggrin
Albinism is due to
defect in tyrosinase gene involved in melanin production
Vitiligo is …
an autoimmune disorder against the melanocyte
vitiligo is ________ depigmentation
acquired
vitiligo microscopic finding
complete absence of melanocytes
vitiligo is commonly seen in
periorificial and acral locations
attachment point of basal cells to the basal lamina of the dermal - epidermal junction
hemidesmosomes
Antibodies to hemidesmosomes cause
bullous pemphigoid
bullous pemphigoid
primary skin lesion?
tense bulla
acquired
bullous pemphigoid
pathogenesis
autoantibodies to bp 180 (collage VII) or BP230
Bullous pemphigoid
pathology
supepidermal blisters
Epidermolysis Bullosa =
a goupd of inherited bullous disorders characterized by blister formation in response to mechanical trauma
Epidermolysis bullosa simplex
defect keratin 5 or 14
epidermolysis bullosa junctional
defect collagen XVII or laminin 5
Epidermolysis bullosa dystrophic
defect in collagen VII
Junctional EB
Genetic defects in laminin 5
clnical:
generalized onset of blisters, improves with age
Recessive dystrophic EB
Defects in collagen VII
clinical
extensive dystrophic scarring can produce pseudosyndactyly
flexion contractures
increased risk of SCC
Infections
thickest layer of epidermis
SS
Desmosomes
specialized structures for cells to cell adhesion
contain intracellular keratin filament 5 and 14
also contain transmembrane proteins, desmogleins and desmocollins
acquired antibodies to desmoglein 1 and 3?
pemphigus vulgaris
pemphigus vulgaris
primary lesions?
flaccid bulla
pemphigus vulgaris
pathogenesis
ab to desmoglein 1 and 3
pemphigus vulgaris
pathology
intraepidermal blisters
EB simplex
pathogeneis
genetic defects in keratin 5 and 14
EB simplex clinical
generalized onset of blisters occur at or shortly after birth - hands, feet, and extremities are the most common sites of involvement
Cells in this layer start to lose their nuclei
SG
Cells in this layer have prominent keratinohyalin granules
SG
Kertainohyalin granules contain
profilaggrin
filaggrin –>
crosslinks keratin in the formation of the cornified cell envelope
lamellar bodies in the SG
Excrete lipids (ceramides)
this layer is made up of dead and desquamating keratinocytes
stratum corneum
the breakdown of filaggrin forms _______________ in the stratum corneym
NMF
Natural moisturzing factor
NMF levels in skin?
decline with age
_________________ are causd by a defective skin barrier function due to loss-of-funtion filaggrin mutations
icthyosis vulgaris
atopic dermatitis
Patients with filaggrin mutations have significantly reduced levels of ________________ in the stratum__________ and exhibit increased transepidermal water loss
NMF
Corneum
Merkel cells
small cells in the epidermis that are associated with nerve endings. Their function has long been uncertain, but they seem to be involved in neural development and tactile sensation - recent evidence supports a role in light touch
flat lesions =
macule or patch
raise lesions =
papule / plaque / cyst / nodule
raised scaly lesions =
papule with scale / plaque with scale
fluid filled lesion
vesicle / bulla / pustule
redness =
erythema / erythroderma / telangiectasia
purpura =
ecchymoses / petechiae / palpable purpura
thinning or loss =
atrophy / erosion / ulcer / fissure
flat area of color change
macule
flat area of color change >1cm
patch
discrete solid elevated body
papule
solid, flat-topped elevated area of skin >1cm and broader than thick
patch
firm and well defined lesion / may be dermal or sub-cu
greater than 1cm
nodule
excess SC
May appear as flakes or plates
color usually white or grey
scale
dried blood / serum / purulen exudate
may be thick or thin
color determined by type of dried fluid
crust
purulent exudate color
yellow-green
serum color
honey
blood color
red-balck
fluid filled cavity or elevation
form below epidermis
vesicle
fluid filled blister
>1cm
bulla
circumscribed elevation that contains pus
pustule
localized blanchable redness
caused by increased blood flow
erythema
generlized blanchable redness
caused by increased bloodflow
may be associated with desquamation or extensive scaling
erythroderma
visible persistnet dilation of small superficial cutaneous blood vessels
telangiectasia
flat discoloration of skin or mucous membranes
due to extravasation of blood
color transitions over time and ranges from blue-black / brown-yellow / or green
ecchymoses (bruise)
tiny 1-2 mm pinpoint spots
resulting from tiny hemorrhages
color is red or violaceous
petechiae
raise and palpable discoloration
due to vascular inflammation and extravasation of RBCs (vaculitis)
color is red or violaceous
palpable purpura
thinning of epidermal / dermal / sub-cu tissue
atrophy
localized loss of epidermal or mucosal epithelium
causes can include injury or denuding of vesicle or bulla roof (Removal
erosion
circumscribed loss of epidermis and at leas upper dermis
ulcer
ulcers are further classified by (3)
depth - can extend to sub-cu / muscle / or bone
edge - can be clean / ragged / undermined
tissue at base - necrotic / purulent / or healthy granulation tissue
a deep linear crack or cleavage
found in areas of thickened skin
fissure
scab
adherent thick dry crust
causes can include trauma / infection / or excoriating skin disease
color is black
eschar (crust)
following lymphatic vessels
lymphangitic
pertaining to a unilateral area of skin innervated by a single posterior spinal nerve
dermatomal
pertaining to palms and soles
palmoplantar
pertaining to sun exposed areas
photodistributed
regions where opposing skin surfaces come in contact and may cause firction
intertriginous
skin surface overlaying muscles that flex joints
flexural