Test 1 Flashcards
What are the 5 layers of epidermis, and what’s special about each?
Californians Love G-String Bikinis
Corneum: dead/dying cells
Lucidum: dead cells prominent in thick epidermis of palms and soles
Granulosum: waterfood, dense basophilic keratohyalin granules
Spinosum: bridged by desmosomes
Basale: keratinocytes, stem cells
What are the diseases found in the 5 layers of the epidermis?
Corneum: psoriasis and warts Lucidum: none Granulosum: warts Spinosum: pemphigus vulgaris, squamous cell carcinoma, seborrheic keratosis Basale: basal cell carcinoma
What are the 3 types of hair?
Languo: fine, downy, unpigmented hair on fetus
Vellus: fine/pale, replaces lanugo by birth, 2/3 of female hair, 1/10 of male hair, kids hair except eyebrows, eyelashes, scalp
Terminal: long/coarse/v pigmented, eyebrows, eyelashes, axillary/pubes after puberty, male facial, some hair on trunk and limbs
What are the 4 types of sensory nerves? and their roles?
Pacinian/lamella corpuscle: mechanoreceptor for pressure and vibration
Meissner’s/tactile corpuscle: light touch, highly sensitive
Nociceptors:
C-fibers: slow pain
A-delta: fast pain
What are the parts of the nail?
Outer: Paronychium, Eponychium, nail groove, Lanula
Nail bed
Nail fold
Nail root
What are the 5 ypes of cutaneous glands?
-Sudoriferous =
Merocine
Apocrine
- Sebaceous
- Ceruminous: modified apocrine, ear wax
- Mammary: modified apocrine
Which embryological layers forms the integumentary sytem?
Ectoderm: Epithelium, assoc glands
Mesoderm: connective tissue of dermis and hypodermis
What is the Epidermis made of (material)?
What’s the Dermis made of (Material)?
Epidermis: keratin in intercellular networks connected by Desmosomes
Dermis: collagen I and III, in extracellular networks, made by fibroblasts
Walk through what connects epidermis to dermis (all the proteins)
Integrin-Laminin-Collagen IV in hexagonal lattice/net-Collagen VII-Collagen I and II of dermis
Differentiate Collagen and Keratin and Fibrillin (bonus, their disease assoc?)
Collagen: triple helix of glycine-proline-hydroxyproline (Ehler’s-Danlos)
Keratin: 2 coiled coils in antiparallel filaments (epidermolysis bullosa simplex)
Fibrillin: releases its bound TGF-beta w/tissue damage to increase cell/tissue growth (Marfan’s)
What are the 3 types of Epidermal Bullosa, and differentiate
Epidermolysis bullosa
1) Simplex: AD, most prevalent, affects cytoskeleton in basal and squamous cells, superficial/skin/nails/hair, can lead to muscular dystrophy and pyloric atresia
2) Junctional: AR, super rare, affects epidermis and BM, significant risk of congenital GU problems, can lead to pyloric atresia
3) Dysmorphic: affects BM and dermis
Differentiate pemphigus vulgaris, pemphigus foliaceus, and bullous pemphigoid in terms of etiology
1) Pemphigus vulgaris: AutoAb against desmoglein 3
2) Pemphigus foliaceus: AutoAb against desmoglein 1
3) Pemphigoid: AutoAb against Hemidesmosomes
Differentiate UVA and UVB rays
UVA: causes tAnning by oxidizing existing melanin, most of UV at sea level, present in all sunlight, penetrates glass and deep into dermis, targets basal cells
UVB: causes sun Burns, signals more melanin production, <5% of UV at sea level, only present at noon/high altitude/lower longitude, targets squamous cells, but still relevant risk factor for BCC, absorbed by DNA
How does Stratum Granulosum layer provide waterproofing?
Granules made mostly of Filaggrin
Filaggrin = histadine rich protein that binds to keratin in cytoskeleton
Skin drying signals Filaggrin degradation, releasing Histadine that helps retain H2o in skin
Histadine = Urocanic acid precursor, which signals skin moistening, immune suppression, and UV protection
Walk through mechanism of UV induced tanning
UV damages DNA in squamous cells
Basal cells upregulate p53
p53 bind to DNA as transcription factor, signaling expression of POMC
POMC cleaved to alpha-melanocyte stimulating hormone (alpha-MSH)
a-MSH binds to Melanocortin1 receptor on Melanocytes, GPCR
Melanocytes stimulated to make more melanin
Melanosomes move to surface
Differentiate Eumelanin and Pheomelanin
Eumelanin blocks UV
Pheomelanin is red/yellow, doesn’t block UV bc Europeans needed more sun to make VItD
What’s genetic cause of Xeroderma Pigmentosum?
XP caused by AR, loss of fx mutation of Nucleotide Excision Repair mechanisms
Skin is under what type of ANS control? What are the receptor types?
Skin is under SNS control
Sweat glands that’re thermoregulatory are mACh
Stress sweat and Pilomotor muscles are alpha-adrenergic
Is sweat hyper, iso, or hypotonic?
Sweat is Hypotonic, salt is removed as fluid is secreted
Where is ‘shivering’ primary motor center? What happens when it activates?
Shivering command starts in Posterior Hypothalamus (dorsomedial, near wall of 3rd ventricle) after it senses cooling via Anterior Hypothalamus
Increases muscle tone
max shivering can increase body heat 4-5x normal
Walk through molecular pathway for non-shivering thermogenesis
In brown fat, SNS’s Epi/NE signals uncoupling of oxidative phsophorylation via mitochondrial uncoupling protein Therogenin
Heat released instead of ATP producted
Who has more brown fat, babies or adults?
Babies have more brown fat, can increase heat production 100%
Adults have little brown fat, can increase heat production 10-15%
How does thyroid help regulate heat? What disease can occur?
Anterior Hypothalamus-preoptic area senses cooling leads to TRH release
leads to Thyroxine release
activates uncoupling protein and increases cellular metabolism through body
extreme cold for weeks can lead to thryoid gland increases 20-40%
leads to goiters
How are fevers produced molecularly?
Fever = pyrogens create cytokines like IL1-1
When does temp regulation start to fail, and what’s the rate?
Temp retulation starts to fail at 94 degrees, and rate of heat production in each cell is depressed 2x for each 10 degree drop
What is frostbite?
Frostbite = ice crystals in cells that leads to permanent circulatory impairment and local tissue damage
How is Pruritis transmitted?
Pruritis: free nerve endings of unmyelinated C fibers to spinal cord’s Anterolateral system
Differentiate Anterolateral vs Dorsalmedial systems of sensory transmission
Anteriolateral: pain, thermal, crude touch, tickle/itch, sexual, much slower and low spatial localization
Dorsalmedial: touch localization and fine pressure gradations, vibratory, movement, joint sensation, much faster and high spatial localization
How do Estrogen and Testosterone affect the skin?
Estrogen: makes skin soft, smooth, more vascular, increased warmth and bleeding when cut
Testosterone: makes skin thick, subQ tissue rugged, increased sebaceous gland activity
What cytokines do Keratinocytes secrete?
Keratinocytes:
inflammatory = IL1, IL6, TNF-a
bactericidal/static beta-defensins
anti-inflammatory = IL10 and TGF-beta
What is the immune mediator for Pemphigus vulgaris?
What’s its target antigen?
Pemphigus vulgaris:
IgG against Desmoglein 3
What is the immune mediator for Bullous pemphigoid
What’s its target antigen?
Bullous pemphigoid:
IgG against hemidesmosome
What is the immune mediator for Dermatitis Herpetiformis?
What’s its target antigen?
Dermatitis Herpetiformis:
IgA against epidermal transglutaminases
What is the immune mediator for Bechet’s disease?
What’s its target antigen?
Bechet’s disease:
IgG against ANCA (antineutrophil cytoplasmic antibodies)
What is the immune mediator for SLE?
What’s its target antigen?
SLE
IgG against dsDNA
What’s the T-cell subtype and target antigen for Psoriasis?
Psoriasis:
Epidermal CD8 and Dermal Cd4, attacking unk
What’s the T-cell subtype and target antigen for Atopic Dermatitis?
Atopic Dermatitis (eczema): CD4 attacking allergens on skin, unk what's inside
What’s the T-cell subtype and target antigen for Allergic contact dermatitis?
Allergic contact dermatitis/hypersensitivity:
CD8 attacking Haptens = small molecules that elicit Type IV hypersensitivity rxn
What’s the T-cell subtype and target antigen for Vitiligo?
Vitiligo:
CD8 attacking melanocyte autoantigens
What’s the T-cell subtype and target antigen for Cutaneous Tcell Lymphoma?
Cutaneous Tcell lymphoma:
CD8, Ag independent
What causes SLE’s malar rash?
extremities/trunk rash?
Chronic Discoid rash
Malar: Ig and/or compliment settle at dermal-epidermal junction
extremities/trunk: Ab to Ro Ag
Discoid: inflammation NOT Ab mediated
Describe pathology behind SJS and TEN
CD4 Th1 release inflammatory cytokines, induce macrophages and PMNs to destroy tissue
CD4 Th2 cells release IL4 and IL5, stimulating eosinophils to cause inflammation and destruction
CD8 cell kill via Fas-Fas ligand and releasing perforin granzymes
What are the HLA alleles that favor presentation of the following drugs to CD8 Tcells (causing drug-mediated skin toxicity)? Carbamazepine Phenytoin Abacavir Allopurinol
Carbamazepine: HLA-B 1502 (esp Asians)
Phenytoin: HLA-B 5601
Abacavir: HLA-B 5701
Allopurinol: HLA-B 5801
Differentiate the following: • Creams • Foams • Gels • Lotions • Occlusive tapes • Ointments • Pastes • Powders • Shampoos • Solutions • Sprays
Cream: H2o + oil, can cause contact allergy
Foam:
Gel: thick polymer solvent, good for hairy
Lotion: liquid w/medication suspension/dissolved in H20>oil, good for hairy
Occlusive tapes
Ointment: semi-solid, good for dry skin bc greasy/sticky/retains sweat (bad for weepy dermatitis)
Pastes:
Powders: base used to apply powders, powders can absorb secretion
Shampoos:
Solutions:
Sprays:
What increases corticosteroid potency?
Steroid potency increases w/fluorinated chemical structure
Name low, moderate, high, and super high topical corticosteroids:
Low: Hydrocortisone
Moderate: Triamcinolone
High: Fluocinonide
Super high: Clobetasol
How much is a finger-tip unit for topical drug use?
finger-trip = 0.5g, and 5mm wide (nozzle on the tube)
What is steroid rosacea?
ide effect commonly observed in fair-skinned people who already have rosacea. A typical example occurs when a person uses a very mild steroid on the face to counteract the facial flushing. This gives pleasing results, but tolerance develops, causing the person to use a higher strength steroid. At this point any attempt to cut down on the steroid application or stop altogether cause intense facial redness and pustules
Where do striae develop when using topical steroids?
Striae develop in groin and armpits, where there’s skin-skin contact
Can use Wood’s Lamp to aid in diagnosing what, and what will you see?
Tinea capitis: Microsporum will look blue-green
Erythrasma: Corynebacterium will look coral-red
Porphyria cutanea tarda: looks pink/orange-red
What do you see in a fungal culture, if there’s a Dermatophyte?
Dermatophyte:
Yellow phenol indicator in media turns Red
What’s the gold standard for skin cancer diagnosis?
BIOPSY
What gets a biopsy?
What gets excisional?
Excision/punch?
Excision shave?
all suspected neoplastic lesions gets a biopsy! Including Bullous disorders!
Excision: Erythema nodosum, Panniculitis Excision/punch: dysplastic nevi, malignant melanoma
Excision/shave: actinic keratoses, BCC, Seborrheic keratosis, pyogenic granuloma, skin tags, SCC, warts
What’s better for max cure rate, excision or Curretage and Electrodesiccation?
Excision!
How to differentiate b/w papule and plaque and nodule?
Papule <0.5cm, vesicle if clear fluid filled
Plaque >0.5cm, bulla if fluid filled
Nodule has DEPTH beneath skin, cyst if fluid filled
What are common drugs that cause Fixed Drug Eruptions? sxs?
Sulfonamides, NSAIDs, ASA, Tetracycline, laxatives, barbiturates
Sxs: erythematous macules/edematous plaques, esp on lips/genitals, upper arm, thigh, tend to reoccur at same site w/re-exposure, chronically results in post-inflammatory hyperpigmentation
What’s pathogenesis behind Fixed Drug Eruptions?
FDE: CD8 act as memory cells to incite next response
Differentiate nevus simplex and port wine stain sxs, tx?
Nevus simplex: congenital, erythematous macule, “Stork bite” or “salmon patch”, esp on back of neck, glabellum, eyelids, fades within 1-2yrs
Port Wine stain: Sturge-Weber syndrome (+seizures, leptomeningeal angiomas), “nevus flammeus”, darker than nevus simplex, doesn’t fade and may become thicker!
Pityriasis rosea sxs? tx plan?
Pityriasis rosea: maybe viral
starts w/single macule “hearld patch”, develops central clearing and peripheral scale (differentiates from secondary syphillis or guttate psoriasis, plus not on palms/soles)
Looks like tinea corporis, but no fungal hyphae
“christmas tree” configuration of many smaller lesions develop 1w-3mo after
Resolves in 6w-months
Melasma sxs? associations?
Melasma = hyperpigmentated macules on face
assoc: women, pregnancy, OCPs, cosmetics, dark skinned, worsened by sun exposure, photosensitizing drugs, thyroid dysufnction
Differentiate Ephelides, Simple Lentigines, and solar lentigines
Ephelides: freckles, same # melanocytes w/larger melanosomes, fades w/sun avoidance
Simple Lentigines/Lentigo: increased # of melanocytes not in nests like mole/nevus, not limited to sun exposed areas, if peri-oral indicative of Peutz-Jegher’s
Solar Lentigines/Lentigo: increased melanin, ‘age/liver spots’ on sun-exposed skin, doesn’t fade w/sun avoidance
Peutz-Jegher’s syndrome presentation?
Peutz-Jegher’s syndrome: AD
pigmented macules on lips/hands/genitalia (aka Simple Lentigines), hamartomatous polyps in GI, increased risk of GI and BrCa