Intro to Derm (complete) Flashcards
Describe the general structure of the skin
- Epidermis (keratinocytes, melanocytes, merkel cells, Langerhans cells [aka DCs])
- Dermis (sebaceous glands, sweat glands, hair follicles)
- Hypodermis
What are the functions of the skin?
1) Barrier
2) Vit D synthesis
3) Water homeostasis
4) Thermoreg
5) Insulation/calorie reservoir
6) Touch/sensation
7) Decoration/beauty
What are the Fitzpatrick Skin Types?
I: Never tans, always burns II: tans w/ difficulty, usually burns III: Average tanning, sometimes burns IV: Easily tans, rarely burns V: Very easy to tan, very rarely burns VI: Never burns
Describe melanocytes and their types
Pigment cells => produce melanin packaged granules called melanosomes (protect from UV)
- Eumelanin: brown to black pigment
- Phemelanin: yellow to red-brown pigment (found in red heads, blondes)
What are the differences in melanin in dark and light skin?
Light skin: melanosomes smaller — distributed in clusters above nucleus in keratinocyte
Dark skin: melanosomes larger and distributed individually throughout the cytoplasm of keratinocyte
Describe Vitiligo
Incidence: 0.5-2%
- Absence of melanocytes
- Acquired depigmentation
- Commonly seen in periorificial and acral areas
Which UV ray helps produce Vit D?
UV B
Not UV A, which are found in tanning beds
Describe the epidermis and its components
Top layer of skin
Components:
- Keratohyalin granules
- Keratinocytes
- Langerhans Cells
- Melanocytes
What are the different layers of the epidermis?
In order from top to bottom:
- Stratum corneum
- Stratum granulosum
- Stratum spinosum
- Stratum basalis
Describe the basal cell layer
the lowermost layer of the epidermis
Has the melanocytes!!
What are hemidesmosomes?
- Attachment point of basal cells to basal lamina of dermal epidermal junction
They connect the epidermis and dermis!!
What is bullous pemphigoid?
Autoimmune => Abs to the hemidesmosomes
Describe the stratum spinosum
- Appears spiny
- B/c cells are held together w/ spiny projections (aka desmosomes)
- Thickest layer of epidermis (above basal layer)
What are desmosomes?
Attachments between keratinocytes
Describe pemphigus vulgaris
AutoAbs to desmosomes
Intraepidermal blisters
Describe keratinocytes
Form skin barrier => protects from microbial, physical, chemical assaults
Also prevents H20 loss
Describe the stratum granulosum
Granular cell layer
- Cells here to loose their nuclei
- Prominent keratohyalin granules contain filaggrin
Describe the stratum corneum
- Made up of dead and desquamating keratinocytes
- Breakdown of filaggrin => forms natural moisturizing factor (binds to water and keeps skin moist)
- NMF levels decline with age
Describe the stratum lucidem
- Extra layer found in thick skin (palm, foot)
- Reduces friction and shear forces between stratum corneum and granulosum
Go look at the histo slide in ppt!!!
What is the clinical word for hair loss?
Alopecia areata
Alopecia universalis (if total hair loss)
What is the clinical word for excess sweating?
Hyper hydrosis
What is a macule?
Flat area of color change
Less than 1cm
What is a patch?
Flat area of color change
More than 1cm
What is a papule?
- Discrete, solid, elevated body
- <1cm in diameter
- May be further classified as scale or crust
What is plaque?
- Solid, flat-topped, elevated
- >1cm and broader than thick
What is a nodule?
- Firm and well-defined
- May be dermal or subcutaneous
- > 1cm
Describe scale
- Secondary feature to further classify papules and plaques
- Surface change
- Excess stratum corneum (outermost layer)
- May appear as flakes/plates
- White or gray
Describe crust
- Dried blood, serum, purulent exudate => forms on skin surface
- May be thick or thin
- Color determined by fluid type
What is a vesicle?
- Fluid filled cavity/elevation
- Form w/in or just below epidermis
- <1cm
What is a bulla?
- Fluid filled blister
- >1cm
What is a pustule?
- Circumscribed elevation
- Contains pus
- <1cm
- Usually whitish-yellow
What is erythema?
- Localized, redness
- Caused by increased blood flow
Think lupus, flushing
What is erythroderma?
- Generalized, blanchable redness
- Caused by increased blood flow
- May be due to desquamation or extensive scaling
What is telangiectasias?
Visible, persistant, dilation of small/superficial cutaneous blood vessels
What are ecchymoses?
A bruise!!
- Flat discoloration of skin/mucous membranes
- Due to extravasation of blood
- Color transitions over time
What is petechiae?
- Tiny 1-2mm
- Tiny hemorrhages
- Red/violaceous
What is palpable purpura?
- Raised/palpable discoloration
- B/c of vascular inflammation/extravasation of RBCs
- Red/violet
What is atrophy?
Thinning of epidermal, dermal or subq tissue
What is an erosion?
- Localized loss of epidermal or mucosal epithelium
- b/c of injury/denuding of vesicle or bulla removal
What is an ulcer of the skin?
Loss of epidermis and at least upper dermis
Classified by:
- Depth
- Edge
- Tissue at base
What is a fissure?
- Deep linear crack/cleavage
- Found in areas of thickened skin
What is eschar?
- A scab
- Adherent, thick, dry crust
- Causes: trauma, infection, skin disease
- BLACK in color
What does lymphangitic mean?
Follows lymph vessels
What does dermatomal mean?
Pertaining to a unilateral area of skin
Innervated by a single posterior spinal nerve
What does palmoplantar mean?
Pertains to palms or soles
What does photodistributed mean?
Pertains to sun exposed areas
What does intertriginous mean?
Regions where opposing skin surfaces come in contact that may cause friction
Under breasts, stomach tissue
What does flexural mean?
Pertains to skin surface overlaying muscles that flex joints
Biceps! Knees!
