Intro to Dermatology and Epidermis Flashcards
What is the most prevalent condition for people seeing their doctor?
skin disorders
What is the most common global skin disease?
Dermatitis (by a lot). Then Acne
What type of epithelium is the most superficial epidermis?
stratified squamous
What are all the components of skin? (layers, etc.)
Epidermis Dermis Adnexal structures subcutaneous fat Regional thick skin layer (on palms, feet)
What are the different adnexal structures?
- Apocrine glands
- Eccrine glands
- Hair
- Nails
- Sebaceous glands
Name the two layers of the dermis
- the papillary layer (loose connective tissue) lies immediately under the epidermis
- a deeper reticular layer (dense connective tissue)
Where do you find keratinocytes?
Epidermis (stratum basale)
They are the stem cells
List the five layers of epidermis from superficial to deep
- stratum corneum
- stratum lucidum (only present in thick skin)
- stratum granulosum
- stratum spinosum
- stratum basale
“california loves girls- stupid and blonde”
“can lovers go (to) second base?”
What do you find in the granules of stratum granulosum
Inside Keratohyalin granules, you find profilaggrin = precursor to filaggrin
What does filaggrin do?
Filaggrin cross-links keratin tonofilaments and is important in the barrier function of the skin
Becomes NMF to moisturize skin
Which layers lost their nuclei and organelles?
corneum and lucidum
What is the important structural characteristic of the stratum spinosum?
Desmosones attach cells together!
Has a “prickly” or spiny appearance due to desmosome attachments between cells
• intercellular adhesion depends upon the tonofilament desmosome interaction in the distribution of stress
What type of epithelial layer is the stratum basale?
Single layer of cuboidal or columnar
How is the stratum basale attached to the dermis?
Hemidesmosomes: attach basal cells are firmly to the basal lamina of the dermal epidermal junction
Where do you find the stem cells of the epidermis?
Stratum basale
Basal keratinocytes are the stem cells of the epidermis (the source of new keratinocytes and thus a site of intense proliferation)
What are tonofilaments?
protein structures (keratin filaments) that insert into the dense plaques of desmosomes on the cytoplasmic side of the plasma membrane
What are the functions of the skin?
- Decoration/Beauty
- Barrier
• Physical
• Light
• Immunologic - Vitamin D synthesis
- Water Homeostasis
- Thermoregulation
- Insulation/Calorie Reservoir
- Touch/Sensation
What cell acts as a light barrier? Where is it found?
melanocyte > epidermis
What cell acts as a physical barrier?
keratinocyte
What cell does vitamin D synthesis
keratinocyte
What cell acts a immunological barrier and where is it found?
Langerhans cells > epidermis
These are the antigen presenting cells (dendrites) of the skin
What cell gives your skin strength and elasticity? Where is it found?
Fibroblast in the dermis (Produces collagen and elastin)
How are the Fitzpatrick skin types classified?
Type I: Never tans, always burns- white
Type II: Tans with difficulty, usually burns- fair
Type III: Average tanning, sometimes burns- light brown
Type IV: Easily tans, rarely burns- moderate brown
Type V: Very easy to tan, very rarely burns- dark brown
Type VI: Never burns- black
T/F: skin color variation is due to number of melanocytes?
False
Due to the type of melanin produced
– Eumelanin: black to brown pigment
– Pheomelanin: yellow to red-brown pigment
Due to the distribution melanosomes
– Light Skin: melanosomes distributed in clusters above the nucleus
– Dark Skin: melanosomes distributed individually throughout the cytoplasm
Again, which type of melanin is darker?
Eumelanin: black to brown pigment
Pheomelanin: yellow to red-brown
Again, does darker skin distribute melanosomes in the cytoplasm or in clusters above the nucleus?
melanosomes distributed individually throughout the cytoplasm
What cells are involved in water homeostasis?
Keratinocytes Eccrine glands (adnexa)
What cells are involved in thermoregulation?
Eccrine glands (adnexa) Blood vessels (dermis)
What glands are involved in lubrication of skin?
sebaceous glands (adnexa)
What disease is from defect with melanin?
Albinism
due to a defect in the tyrosinase gene involved in melanin production
What is the mechanism of vitiligo?
Autoimmune destruction of melanocyte
T/F: vitamin D2 and D3 can be ingested in food?
True
Where are Vit D2 and D3 converted to calitriol?
Liver
Where is the active form of vitamin D (calcidiol) synthesized?
Kidney
T/F: Vitamin D2 and D3 are both synthesized/converted by the sun
False: only Vitamin D3 is converted by UVB rays
(it can also be acquired through diet
What are the three different glands?
Apocrine: viscous, in axila and pubic regions, empty into hair follicles just above sebaceous glands
Eccrine: traditional, watery sweat glands all over body important in thermoregulation
Sebaceous: secrete sebum, develop along with hair follicles
Characteristics of papillary layer of dermis?
- site of attachment to epidermis
- contains capillary network that is blood supply for epidermis
- pathway for defense cells
- contains Meissner’s corpuscles which sense touch
Characteristics of reticular layer of dermis?
- contains extensive collagen and elastic fibers that provide strength and flexibility
- pathway for major blood vessels arranged specifically to facilitate thermoregulation
- site of nerve tracts and major sensory receptors-Pacinian corpuscles sense vibration, pressure and touch
What causes bullous pemphigoid?
blisters all over skin caused by autoantibodies to HEMIDESMOSONES
What is epidermolysis bullosa?
Blisters from mechanical stress from defects in any of the following: hemidesmosones, collagen, laminin, etc
(there are different types caused by pretty much any kind of connective tissue defect)
What skin structure is defective in pemphigus vulgaris?
Desmosones: from antibodies
What are conditions caused by filaggrin mutations?
Icthyosis Vulgaris and Atopic Dermatitis
Severely dry skin
What is NMF? (hint: natural moisturizing factor)
Broken down form of filaggrin that binds water to keep skin moist
-decreases with age
What are terms for a flat skin lesion?
macule/ patch
What are terms for a raised, smooth skin lesion?
papule/ plaque/ nodule/ cyst
What are terms for a raised, scaly skin lesion?
papule with scale/ plaque with scale
What are terms for a fluid filled skin lesion?
vesicle (fluid 1 cm), pustule (pus filled)
What are terms for a bruising lesions?
purpura/ ecchymoses/petechiae/palpable purpura
What are terms for redness?
erythema (redness)/ erythroderma (generalized redness)/ telangiectasia (visible dilation of small vessel)
