Unit 3a Flashcards
Functions of the skin (7)
Decoration Barrier (physical, light, immunologic) Vitamin D synthesis Water Homeostasis Thermoregulation Insulation/Calorie Reservoir Touch/Sensation
How can we get vitamin D?
Produced in response to exposing the skin to sunlight, but also acquired in foods
From sun (D3) or diet (D3 or D2) –> calcidiol in liver –> calcitriol active form in kidneys
Cells present in Epidermis (3) and their basic functions
Keratinocytes = physical barrier, vitamin D synthesis, water homeostasis
Melanocytes = light barrier
Langerhans cells = immunologic barrier
Glands of the Adnexa and their function (3)
Eccrine glands = water homeostasis, thermoregulation
Sebaceous glands = lubrication of the skin
Apocrine glands = pheromones/body odor
Structures of the Dermis and their function (3)
Blood vessels = thermoregulation
Fibroblasts = strength and elasticity
Nerves = sensation
Function of the subcutaneous fat layer
insulation, calorie reservoir
Fitzpatrick skin type I:
Hair Eyes Skin Freckles? Sunburn? Tan?
red/blond hair blue-green eyes white skin \+++ freckles Always sunburn no tan
Fitzpatrick Skin Type II
Hair Eyes Skin Freckles? Sunburn? Tan?
Blond/Brown hair Light to medium eyes Fair skin \++ freckles easily sunburns minimally tans
Fitzpatrick Skin Type III
Hair Eyes Skin Freckles? Sunburn? Tan?
Brown hair medium to dark eyes light brown skin \+ freckles Initially sunburn Gradually tans
Fitzpatrick Skin Type IV
Hair Eyes Skin Freckles? Sunburn? Tan?
Medium to dark hair dark eyes moderate brown skin no freckles minimally sunburns tans well
Fitzpatrick Skin Type V
Hair Eyes Skin Freckles? Sunburn? Tan?
dark hair dark eyes dark brown skin no freckles rarely sunburns dark tan
Fitzpatrick Skin Type VI
Hair Eyes Skin Freckles? Sunburn? Tan?
dark hair dark eyes black skin no freckles never sunburns always tan
Skin color NOT due to ___________
number of melanocytes in the skin
Skin color due to…(2)
type of melanin produced
distribution of melanosomes
Melanin Types:
Eumelanin –> _________ pigment
Pheomelanin –> __________ pigment
Eumelanin → black/brown pigment
Pheomelanin → yellow/red-brown pigment (skin type I and II)
Distribution of Melanosomes:
Light skin –> ?
Dark skin –> ?
Light skin → smaller, distributed in clusters above nucleus in keratinocyte
Dark skin → larger distributed individually throughout cytoplasm of keratinocyte
Albinism is a defect in the ________ gene involved in ____________
tyrosinase
melanin production
Vitiligo
autoimmune attack of melanocyte
Acquired depigmentation - complete absence of melanocytes
Depigmented patches and macules
Keratinocytes
form barrier layer
Synthesize keratin (major intracellular fibrous protein of skin)
Involved in cycle of proliferation, differentiation, and apoptosis
Melanocytes
pigment producing cells
Arise from neural crest
Located in basal layer of epidermis, in hair follicles
1:10 ratio (melanocyte:keratinocyte)
Each melanocyte supplies melanin to 30 keratinocytes
Absence of melanocytes usually due to autoimmunity (EX-vitiligo)
Melanin
pigment derived from tyrosine
synthesized by melanoyctes, packaged in granules called melanosomes
protects DNA from UV damage
Langerhans Cells
dendritic cells, participate in cell-mediated immunity
Derived from bone marrow stem cell
Cycle back and forth between skin and lymph nodes
Found in small numbers in all the epidermal layers
Merkel Cells
small cells associated with nerve endings in epidermis
Role in light touch (?) - unknown
The Dermis is the… and made up of which two layers?
underlying CT layer (below epidermis)
Papillary layer
Reticular layer
Papillary layer
structure (1) function (5)
(loose CT) immediately under epidermis
1) Site of attachment to epidermis
2) Important for epidermis development and differentiation
3) Contains capillary network blood supply for epidermis
4) Pathway for defense cells
5) Contain Meissner’s Corpuscles (sense delicate touch)
Reticular layer
structure (1) function (4)
dense CT, deeper than pap layer
1) Extensive collagen and elastic fibers for strength and flexibility
2) Houses glands, hairs - major role in their development/function
3) Site of nerve tracts and major sensory receptors
4) Pacinian corpuscles sense vibration, deep pressure, and touch
Pacinian corpuscles are located in the ________ layer, while Meissner’s Corpuscles are located in the _________ layer
reticular
papillary
subcutaneous fat is composed of ________
adipocytes
Layers of epidermis from deep to superficial (5)
1) Stratum basalis
2) Stratum spinosum
3) Stratum granulosum
4) Stratum lucidum
5) Stratum corneum
Stratum basalis (5 characteristics)
Basal Cell Layer
Single layer of columnar or cuboidal cells (keratinocytes)
Basal keratinocytes = stem cells of epidermis
Contains Hemidesmosomes and Desmosomes
Deepest layer of epidermis
Stratum spinosum (3 characteristics)
“Prickly” appearance due to desmosome attachments between cells
Intracellular adhesions use tonofilament-desmosome interaction to distribute stress
Synthesis of involucrin and membrane coating granules begins here
Stratum granulosum
cell in this layer contain different types of granules
E.g. Keratohyalin granules
Keratohyalin granules
contain profilaggrin → Filaggrin which cross-links keratin tonofilaments
Important in barrier function of skin
Mutation in Filaggrin → dry skin conditions (ichthyosis, atopic dermatitis)
Stratum lucidum (2)
thin, light staining band, seen only in thick skin
Cells have no nuclei or organelles
Stratum corneum (3)
outermost layer of epidermis
Keratinocytes have lost nuclei/organelles - entire cell filled with keratin
Desmosomes still connect tightly packed adjacent cells
Hemidesmosomes
attach basal cells to basal lamina at dermal-epidermal junction
Ab to hemidesmosomes →
bullous pemphigoid
autoimmune subepidermal blistering disease
Genetic defect in Colagen VII –> _____________
Dystrophic Epidermolysis Bullosa (EB)
Extensive dystrophic scarring
blistering with skin damage
Genetic defect in laminin-5 –> ?
Junctional EB
Improves with age
Desmosomes
attach keratinocytes to each other (contain intracellular keratin)
Ab to desmosomes –> ?
autoimmune blistering disease (pemphigus vulgaris)
Defect in keratin filament 5 and 14 –> ?
Epidermolysis Bullosa Simplex
Tonofilaments
protein keratin structures that insert into desmosomes on cytoplasmic side of the plasma membrane
Thick skin (3)
hairless
found on palms and soles
has stratum lucidum
Raised and smooth:
less than 1cm
>1cm
>1cm+firm
Papule
Plaque
Nodule
Flat area of color change:
less than 1 cm
> 1cm
Macule
patch
Fluid filled (3)
Vesicle (less than 1cm)
Bulla (>1cm)
Pustule (less than 1cm, contains pus)
Blanchable redness due to increased blood flow =
Erythema
Erythroderma
telangiectasia
Erythema = localized
Erythroderma = generalized
Telangiectasia = dilation of small, superficial subcutaneous blood vessels, persistent
Atrophy vs. erosion vs. ulcer vs. fissure
Atrophy = thinning of epidermal, dermal, or subcu tissue
Erosion = localized loss of epidermal or mucosal epithelium
Ulcer = loss of epidermis and at least upper dermis
Fissure = linear crack or cleavage
Stasis dermatitis is present on ___________ and is associated with __________
Lower legs
Lower extremity efema
Stasis Dermatitis morphology and location of inflammation
Morphology: erythematous papules and thin plaques with scale
Location of inflammation: epidermis and dermis
Cellulitis morphology and location of inflammation
Morphology: warm, tender, erythematous patches or plaques
Location of inflammation: dermis and subcutaneous tissue
Seborrheic Dermatitis is present on ________ and is due to irritation from _________
scalp
Malassezia furfur (yeast) and overproduction of skin oil
Psoriasis is typically located on _______ while atopic dermatitis is located on _______
extensor surfaces
flexor surfaces
Psorasis is associated with _______ and ________ diseases
arthritis and cardiovascular
Atopic dermatitis is _______, due to defect in _________. It is associated with _______ and _________
dry skin
filaggrin
Associated with asthma and allergic rhinitis
Nummular dermatitis is located on __________, and is often caused by ____________
legs mostly, but also arms and trunk
excess use of soap and dry skin
Irritant dermatitis caused by contact with irritating substance. Common irritants are…(7)
soap, water, skin products, perfumes, wool, raw foods, body secretions, friction
Allergic contact dermatitis is caused by contact with allergen resulting in ____________.
Common allergens include (3)
Delayed type hypersensitivity (Type IV)
1) Nickel (#1 cause)
2) Fragrance
3) Neomycin/Bacitracin
Diagnosis of allergic contact dermatitis is done with _________
patch testing
Dermis (4)
tough elastic support structure
provides TENSILE strength
beneath epidermis, above subcutaneous tissue
provides ALL nutritional support to epidermis
Dermis matrix is made up of…(3)
1) Collagen - forms the tensile strength
2) Elastic Fibers - allow for resilience
3) Ground substance - facilitates diffusion
_________ makes up 85% of adult dermis and bone and provides _______ strength
Collagen I
tensile
Synthesis of collagen
1) Procollagen synthesized intracellularly in fibroblast
Procollagen = 3 separate protein chains in a-helix structure, EXCRETED
2) Secreted and assembled into collagen fibrils EXTRACELLULARLY
3) Requires vitamin C (for cross-linking) + other cofactors for extracellular assembly
Glycine + proline + hydroxyproline
Elastic fibers
provide skin with resiliency (ability to distort and return to original shape)
Thin fibers intertwined among collagen bundles
Histology:
________ = large eosinophilic (pink)
________ = argyrophilic (silver)
Collagen
Elastin
Dermis ground substance
Glycosaminoglycans + Fibronectins
gelatinous material between/amongst collagen bundles, elastic fibers, and appendageal structures of the dermis
Ground substance is produced by _______ and destroyed by __________
fibroblasts
enzymes (hyaluronidase)
Glycosaminoglycans (GAGs)
two kinds
(GAGs) proteins + sugars, absorb water, allows diffusion
1) Hyaluronic acid
2) Dermatan Sulphate
Fibronectins act to ___________
glue GAGs together
Ehlers-Danlos Syndrome (EDS)
disorder of COLLAGEN SYNTHESIS
- Skin hyperextensibility
- Joint hypermobility
- Tissue fragility
- Poor wound healing
- Gorlin’s sign (touch tip of nose with tongue)
Scurvy
vitamin C defect → collagen synthesis problem
Collagen synthesis problems (2)
scurvy
Ehlers-Danlos Syndrome (EDS)
Solar Elastosis
acquired disorder of ELASTIC FIBERS
Accumulation of significant sunlight exposure → degeneration of elastic fibers → collagen bundles dystrophic and aggregate
Sun-damaged elastic fibers = basophilic (blue) staining
Indicative that sample is from a middle-aged, older person
Function of Blood Vessels in dermis layer
1) Wound healing
2) Control of homeostasis
3) Modulation of inflammation/leukocyte trafficking
4) Provides ALL blood and nutrients to epidermis
Blood vessels are located in the _________ portion of the ___________
suprapapillary portion, upper portion of papillary dermis
Blood vessels of the dermis are divided into two plexi: ________ and _________
superficial and deep
Psoriasis can result in _________ after removal of a scaled area of skin
Auspitz sign (pinpoint bleeding)
Verruca (warts)
viral neoplasms with increased blood supply
Leukocytoclastic vasculitis
disease involving postcapillary venules
Caused by precipitation of immune complexes in walls of small vessels
Type III - Gell and Coombs reaction pattern
“palpable purpura” (combo of inflammation + hemorrhage)
Examples of disorders of vascular supply (3)
1) Psoriasis
2) Verruca (warts
3) Leukocytoclastic vasculitis
Function of nerve tissue
inform and protect
Pacinian Corpuscle
Resemble and onion
Involved in pressure and vibratory sensation
Rapidly adapting, single sensory nerve fiber termination
In dermis of thin and thick skin
Large-concentric layers of flattened CT-like cells interspersed with intercellular fluid/collagen
Meissner’s Corpuscle
Pine-cone structure
Located near DEJ
Involved in fine touch, tactile discrimination
High concentration in distal aspects of digits
In dermal papillae of THICK skin
Free Nerve endings (two types)
Pass through upper dermis, terminate in dermoepidermal junction
Type A
Type C fibers
Type A nerve fibers
myelinated, conduct rapidly
Type C nerve fibers
unmyelinated, slow conducting
Convey sensation of diffuse, dull, non-localizing
Temperature and itching sensation (PURITIS)
Itch and pain are different and INDEPENDENT sensory modalities
Disorders of innervation of the skin
Congenital Insensitivity to Pain + Anhidrosis (inability to sweat)
Mutation in neurotrophic tyrosine receptor kinase 1 (NTRK1) which encodes for nerve growth factor (NGFR)
Apocrine Glands:
location
secretion composition
initiation of function
3 examples
specialized sweat glands
Location: axillary, pubic, and perianal regions
Secretion: Produce milky, viscid, carb-rich secretion (initially odorless → bacterial action → body odor)
Begin to function in puberty (respond to sympathetic adrenergic stimuli)
EX) Moll’s glands (eyelids), cerumen (ear wax), lactation glands (breasts)
Structure of apocrine glands
coiled portion deep in dermis + straight duct (traverses dermis) + empties into hair follicle
Surrounded by contractile myoepithelial cells
Apocrine glands use _________ secretion which is…
Decapitation secretion
apical portion of secretory cell cytoplasm pinches off and enters the lumen
Eccrine glands
Location
Secretion composition
Function
traditional sweat glands all over body
Location: Most numerous on forehead, upper cutaneous lip, palms/soles
-NOT in lips, under nails, on glans penis/clitoris, or labia minora
Secretion: Odorless, watery sweat
-Water, enzyme-rich secretions (initially isotonic → hypotonic as Na+ is reabsorbed by the ducts)
VITAL for thermoregulation - cooling via evaporation of sweat
Eccrine glands use __________ secretion which is…
Sweating is mediated by __________
Merocrine
-secrete WITHOUT apocrine blebbing or holocrine shedding
SYMPATHETIC portion of ANS - triggered by Ach secretion
Apoeccrine Glands
hybrid sweat glands
In axilla (role in hyperhydrosis)
Respond to cholinergic stimuli
Long ducts open to surface
Secrete 10x as much sweat as eccrine glands
Two types of hairs
Terminal Hairs:
- large, thick, coarse, pigmented (scalp, beard, chest, back, pubic areas)
- At/near dermal-subcutaneous junction
Vellus Hairs:
-small, fine, apigmented, diffuse on body
Embryology of hair
Derived from primitive ectodermal germ (PEG)
Underlying mesenchyme (becomes dermal papillae) INDUCES formation of PEG in the overlying fetal skin
Develop in utero - down growth of epidermis forming pilosebaceous unit
Hair embryology
Lower bulge –> ?
Middle bulge –> ?
Upper Bulge –> ?
Lower Bulge: attachment for arrector pili
Middle Bulge: sebaceous gland
Upper Bulge: apocrine gland
Structure of hair (3 segments)
Infundibulum - upper third of hair follicle
Isthmus - middle (sebaceous duct to insertion of arrector pili)
Matrical area - lower third (bulb)
Central medulla (soft keratin) + cortex + cubicle of hard keratin
Arrector Pili Muscle
smooth muscle
Contraction → hair stands on end (goose bump)
Hair growth - 3 phases
Growth is intermittent (grow 2-3 years, rest several months)
Anagen (growth) - 3 yrs
Telogen (rest) - 3 mos
Catagen (involution) - 3 days
Sebaceous glands
oil glands, secrete sebum (complex mix of lipids) onto hair
Develop with hair follicles
Development accelerated at puberty - sex hormones requisite to sebum secretion
In oily areas of the body (scalp, face, neck, upper chest, upper back)
Sebaceous glands use _________ secretion which is….
Holocrine secretion
involves entire sebocytes being secreted
Androgenic Alopecia
finer, miniaturized, hair higher in dermis
Terminal hairs → vellus hairs (miniaturization of hair follicles)
Aka “pattern baldness”, affect 50% of population
Acne
disorder of pilosebacceous unit (hair follicle + oil gland)
Follicle becomes plugged, oil accumulates
Bacteria, P. acne cause follicle to rupture → inflammation
Anhidrotic Ectodermal Dysplasia
Mutation in EDA gene
Aberrant eccrine development
Severely decreased sweating** → Poor temperature regulation
Other ectodermal problems (sparse hair**, abnormal teeth, etc.)
Chromohidrosis
“colored sweat”
Apocrine origin, lipofuscin pigment causes colored sweat
Hyperhidrosis
- involving eccrine and/or apoeccrine glands
- Excessive sweating
- New treatment: botox - blocks release of Ach from nerves → block sweat production
Seborrheic Dermatitis
1 symptom and its location?
5 associated diseases
severe dandruff - scalp, face, upper torso
Diseases: Parkinson’s, head trauma, HIV, chronic neurologic conditions (cerebral palsy), PTSD
Acanthosis nigricans
- new onset of soft dark areas in skin folds, hands and neck = “velvet neck”
- Familial-AD (rare), Drugs (Rare)-nicotinic acid, systemic steroid
- Related to obesity, DM, endocrinopathies (Cushing’s, PCOS)
- May precede, accompany, or follow onset of cancer: rapid onset, associated weight loss
Skin signs of diabetes (4)
1) yellow skin
2) brown/red patches on lower legs
3) diabetic foot ulcers (mal perforans)
4) disseminated granuloma annulare (a whole bunch)
Ehlers-Danlos skin signs (3)
increased joint/skin elasticity
poor wound healing (large scars)
increased ecchymoses
Infective Endocarditis skin signs (6) + other associated symptoms
1) splinter hemorrhages in nails
2) purpura
3) nail fold changes
4) Janeway lesions (acute)
5) Osler’s nodes (subacute)
6) Roth spots (eyes)
- Fever of unknown origin, malaise, fatigue, night sweats, SOB, blood in urine and cough
- Strep viridans from teeth
PHACES Syndrome (peds)
large hemangioma of face and neck, affects cervical arteries and heart
Marfan’s Syndrome
tall, skinny, decreased subcutaneous fat
Sarcoidosis (4 signs)
1) hyperpigmented plaques
2) erosive/ulcerated plaques
3) granulomatous reactions in tattoos, walled off granulomas
4) Bilateral hilar lymphadenopathy
Scleroderma (6 skin signs + other)
1) thickened skin over fingers and hands
2) tightening around mouth
3) “Lost smile”
4) Pain in finger tips
5) Reduced ROM with tight feeling
6) salt/pepper skin changes
Other: SOB, difficulty eating
Lichen Planus (3)
1) new onset itchy rash wrists/lower legs, sores in mouth
2) Purple, polygonal pruritic papules
3) Wickman’s striae
Porphyria Cutanea Tarda (PCT)
4 skin signs
underlying defect
treatment
1) blistering lesions on hands with sun exposure
2) hypertrichosis
3) atrophic white scars with milia
4) Associated with hepatitis
Due to deficiency in uroporphyrin decarboxylase
TX:
serial phlebotomy to decrease iron load
Pyoderma Gangrenosum (PG)
punched out ulcers with necrotic sharply demarcated (undermined) border
Associated with Inflammatory Bowel Disease, UC, Crohns, Arthritis
Usually on lower extremities
AVOID surgery and debridement - treat with immunosuppressants and corticosteroids
Cullen’s sign and Grey Turner
sign of bleeding in peritoneum
Cullen’s sign (periumbilical bruising) Grey Turner (bruising on flanks)
Sign of blunt trauma to abdomen, acute pancreatitis
Koilonychia
seen with chronic iron deficiency
Hair loss, heavy/irregular menses, nail changes (spoon)
Lupus (4 skin signs)
Malar Rash
Discoid Rash
Oral Ulcers
Photosensitivity
Acanthosis nigricans with tripe palms → ______ malignancy
GI malignancy
Erythema Gyratum Repens (= ?) and Hypertrichosis lanuginosa acquisita (= ?) → _________
Erythema Gyratum Repens = abnormal wood-grain pattern on skin
Hypertrichosis lanuginosa acquisita = fuzzy hair on face
LUNG cancer
Dermatomyositis (rash on upper chest = shawl + purple around eyes) –> ?
ovarian/female reproductive malignancy
Sister Mary Joseph Node (near belly button) → ?
Pancreatic, GI cancer
weet Syndrome (big pustules on hand/face + fever) –> ?
AML
Terry’s nails
(distal erythema) → cirrhosis or CHF
Linsay’s nails
(half and half red/white) → renal disease
Yellow nails, thickened nails, growth interruption all reflective of internal health
Rash + fever + headache…think what?
ticks
