Introduction to Dermatology Flashcards Preview

Disease & Defense - Unit 3 > Introduction to Dermatology > Flashcards

Flashcards in Introduction to Dermatology Deck (31):

Functions of the skin (7) and structure/cells involved

1. Decoration=skin, hair, nails, lips
2. Barrier
-physical=epidermis: keratinocytes
-light=epidermis: melanocytes
-immunologic=epidermis: langerhans cells
3. Vitamin D synthesis=epidermis: keratinocytes
4. Water homeostasis=epidermis: keratinocytes & Adnexa: eccrine glands
5. Thermoregulation=adnexa: eccrine glands & dermis: blood vessels
6. Insulation/Calorie Reservoir=subcutaneous fat
7. Touch/sensation=dermis: nerves


Structure/Cells involved in: 1. grasp 2. lubrication of skin 3. pheromones/body odor

1. grasp=adnexa: nails
2. lubrication=adnexa: sebaceous glands
3. pheromones/body odor=adnexa: apocrine glands


Structure/cells involved in strength and elasticity of skin

-dermis: fibroblast --> produces collagen and elastin


Characteristics of Fitzpatrick Skin Type I: Hair, Eyes, Skin, Freckles, Sunburn, Tan

-Hair: red/blond
-Eyes: blue/green
-Skin: white
-Freckles: +++
-Sunburn: always
-Tan: 0


Characteristics of Fitzpatrick Skin Type II: Hair, Eyes, Skin, Freckles, Sunburn, Tan

-Hair: blond/brown
-Eyes: light to Medium
-Skin: fair
-Freckles: ++
-Sunburn: easily
-Tan: minimally


Characteristics of Fitzpatrick Skin Type III: Hair, Eyes, Skin, Freckles, Sunburn, Tan

-Hair: brown
-Eyes: medium to dark
-Skin: light
-Freckles: +
-Sunburn: initially
-Tan: gradually


Characteristics of Fitzpatrick Skin Type IV: Hair, Eyes, Skin, Freckles, Sunburn, Tan

-Hair: medium to dark
-Eyes: dark
-Skin: moderate brown
-Freckles: 0
-Sunburn: minimally
-Tan: tans well


Characteristics of Fitzpatrick Skin Type V: Hair, Eyes, Skin, Freckles, Sunburn, Tan

-Hair: dark
-Eyes: dark
-Skin: dark brown
-Freckles: 0
-Sunburn: rarely
-Tan: dark tan


Characteristics of Fitzpatrick Skin Type VI: Hair, Eyes, Skin, Freckles, Sunburn, Tan

-Hair: dark
-Eyes: dark
-Skin: black
-Freckles: 0
-Sunburn: never
-Tan: always tan


Major components of the skin (4)

1. Epidermis=stratified squamous epithelial layer
2. Dermis= underlying connective tissue layer= papillary layer (loose connective tissue) + deeper reticular layer (dense connective tissue)
3. Adnexal structures: Apocrine glands, Eccrine glands, hair, nails, Sebaceous glands
4. Subcutaneous fat=adipocytes


Characteristics of thick skin

-found @ palms and soles of feet


Layers of epidermis (superficial --> deep)

-stratum corneum
-stratum lucidum (thick skin only)
-stratum granulosum
-stratum spinosum
-basal layer


Characteristics of keratinocytes

-form barrier layer
-synthesize keratin --> intracellular fibrous protein
-defined cycle of proliferation, differentiation, and apoptosis


Characteristics of melanocytes

-pigment-producing cells (melanin <-- tyrosine)
-located @ basal layer of epidermis, hair follicles
-melanin packaged in granules (melanosomes) and transfered to ~30 neighboring keratinocytes via dendritic processes
-melanin protects DNA from UV damage


Characteristics of Langerhans cells

-small amounts present in all epidermal layers
-dendritic cells in epidermis
-cell-mediated immune reaction participation through processing and presentation of antigens


Main factors determining skin color variation

1. type of melanin produced
-eumelanin=black to brown pigment
-pheomelanin=yellow to red-brown pigment
2. distribution of melanosomes
-light skin=melanosomes in clusters above
-dark skin=melanosomes distributed individually
throughout the cytoplasm


General life cycle of keratinocytes

-epidermis continually renewed by mitosis of keratinocytes in basal layer and shedding @ surface
-entire cycle=28 days


Basal cell layer (stratum basalis) characteristics

-deepest layer of epidermis
-single layer of columnar or cuboidal cells (keratinocytes)
-basal keratinocytes=stem cells of epidermis


Important keratinocyte cell attachments (3)

-hemidesmosomes: attach basal cells to basal lamina
-desmosomes: attach keratinocytes to each other
-tonofilaments: keratin filaments that insert into dense plaques of desmosomes on cytoplasmic side of plasma membrane


Stratum spinosum characteristics

-layer just superficial to basal layer
-"prickly" apperance b/c desmosome attachments
-intercellular adhesion dependent on tonofilament-desmosome interactions
-synthesis of involucrin and membrane-coating granules begins here


Stratum granulosum characteristics

-cells contain granules
-Keratohyalin granules contain Profilaggrin (filaggrin precursor).
-Filaggrin cross-links keratin tonofilaments and is important in the barrier function of the skin.


Stratum lucidum characteristics

-thin, light staining band seen only in thick skin
-cells have no nuclei or organelles


Stratum corneum characteristics

-outermost layer of epidermis
-keratinocytes have lost nuclei and organeles
-entire cell filled w/keratin
-desmosomes still connect tightly packed adjacent cells


Papillary layer characteristics

-superficial layer of dermis
-attaches to epidermis
-contains capillary network that is blood supply for epidermis
-pathway for defense cells
-contains Messner's corpuscles which sense touch


Reticular layer characteristics

-deeper layer of dermis
-extensive collagen/elastin fibers --> strength and flexibility
-houses epidermal derivatives (glands, hairs) and plays role in their development and fxn
-pathway for bvs that facilitate thermoregulation
-site of nerve tracts and major sensory receptors
-pacinian corpuscles sense vibration, pressure, and touch


Meissner's corpuscles characteristics

-detect delicate touch
-found in the dermal papillae of thick skin
-consist of Schwann cells and sensory nerve terminals wrapped by fibroblasts and collagen


Pacinian copuscles

-receptors that detect changes in deep pressure (vibrations)
-found in the dermis of both thin and thick skin
-large structures resembling an onion
-the concentric layers are composed of flattened connective tissue-like cells interspersed with intercellular fluid and collagen
-a single sensory nerve fibers terminates within this structure


Apocrine sweat gland characteristics

-specialized sweat glands located in the axillary, pubic and perianal regions
-produce a milky, viscid, carbohydrate-rich secretion that is initially odorless
-bacterial action on secretions leads to a characteristic axillary body odor
-begin to function in puberty
-have ducts which empty into hair follicles just above sebaceous glands


Eccrine sweat gland characteristics

-Traditional sweat glands distributed over most of the body
-Not found in the lips, under the nails or on the glans penis, glans clitoris, or labia minora
-Watery, enzyme-rich secretion, initially isotonic, becomes hypotonic as Na+ is reabsorbed by the ducts
-Important for thermoregulation


Hair characteristics

-Develop in utero with downgrowth of the epidermis forming a pilosebaceous unit
-The hair itself consists of a central medulla of soft keratin, and a cortex and cuticle of hard keratin.
-Hair growth is intermittent
-Pigment comes from melanocytes at the base of the hair
-With contraction of the arrector pili muscle (smooth muscle), hairs stand on end (“goose bumps”)


Sebaceous glands characteristics

-Oil glands which secrete sebum=a complex mixture of lipids
-develop along with hair follicles and empty their secretion into the upper one-third of hair follicles
-development accelerated at puberty