Flashcards in Introduction to Dermatology Deck (96):
skin is the __ of the body
main physiological functions of skin are... (10)
1) protection - acts as barrier against water entry/loss, chemicals, various microorganisms, and minor trauma
2) sensation - contains nerve receptors, and small nerve endings for touch, position, pressure, temperature and pain
3) thermoregulation - eccrine sweat glands
4) immunological defense - langerhans cells
5) vitamin d synthesis - through sun exposure
6) pigmentation - UV protection
7) wound healing
8) reproductive function - sexual attractiveness may depend on smell and appearance of skin
10) absorption and excretion
two main regions of skin are...
role of dermis and epidermis
each provide a distinctive role in the overall function of skin
what is the dermis attached to?
hypodermis is also called...?
subcutaneous connective tissue
what is hypodermis also recognized as in gross anatomy?
what's the function of the hypodermis
store adipose tissue
which structures does the skin consist of?
epidermis, dermis, subcutaneous fat, appendages
what kind of tissue is epidermis?
statified squamous epithelium
what does epidermis consist of?
keratinocytes, dendritic cells, langerhans cells, merkel cells
into how many layers can the epidermis be subdivided into?
which layers can the epidermis be subdivided into?
stratum basale (basal layer), stratum spinosum (spinous or prickle cell layer), stratum granulosum (granular layer), stratum lucidum, stratum corneum (surface layer)
the basal layer consists of...
1 cell layer of cuboidal cells attached by hemidesmosomes to a thin basement membrane which separates it from the underlying dermis
what causes the characteristic "prickles" of the stratum spinosum (prickle-cell-layer)?
spinous cells are separated from each other by lots of intercellular connections (desmosomes) which causes this appearance under the microscope
the process of the stratum granulosum (SGR) cells to accumulate dense basophilic keratohyalin granules. inside these granules are lipids. together with desmosomal connections, this helps to form a water-proof barrier to prevent fluid loss
what does the thickness of epidermis depend on and does it vary?
- varies throughout body
- depends on frictional forces so thickest on palm and soles
where is stratum lucidum only seen and its a transition of what?
- in thick epidermis
- transition from s. corneum to s. granulosum
what is the s. corneum (SC) made up of?
dead and dying cells containing mature keratin
do stratum corneum cells have desmosomal junctions?
the deeper ones do but lose them when they're pushed further to the surface by new cells formed in the stratum germinativum (basal layer)
dead cells in the s. corneum that break apart and are shed from the surface
how long is the cycle of a keratinocyte? (normal cornification)
from basal layer to s. granulosum - 14 days
from stratum granulosum to surface - 14 days
28 days in total
how do basal and cornified keratinocytes differ?
basal - mitotically active, contain least keratin
cornified - mitotically inactive, contain most keratin
when is the keratin in keratinocytes synthesized?
what is the function of keratin?
- gradually, as it moves upward to the surface
- serve as a protective barrier between body and environment
epidermal transit time
the time it takes for keratinocytes to move from basal to surface layer, 28 days
what are melanocytes?
they produce melanin for skin pigmentation
what is a melanosome?
organelle within melanocyte which contains melanin (pigments)
what do melanosomes do?
they are transported by melanocyte dendrites to keratinocytes where they form a cap over their nucleus to protect them against UV radiation
how is melanin synthesis controlled?
by melanocyte stimulating hormone (MSH) in the pituitary gland
what are langerhans cells?
- dendritic antigen-presenting cells
- involved in immune response of the skin
the dermis is subdivided into...
papillary and reticular layers
the dermis is mainly made up of...
what are the functions of fibroblasts in the dermis?
secrete collagen, elastin, and ground substance that make the skin elastic, and provide support
besides fibroblasts, what else is present in the dermis?
immune cells, involved in the defense against foreign substances invading the epidermis
what does the papillary dermis contain and what are its functions?
- vascular network
1) provide vital nutrients to avascular epidermis
2) thermoregulation - heat can be conserved or dissipated through decreased or increased blood flow through this vascular network respectively
what are the areas called in which the vasculature of the papillary dermis interdigitates?
dermal papillae (DP)
besides a vascular network, what else does the papillary dermis contain?
- free sensory nerve endings
- Meissner corpuscles (in the highly sensitive areas)
what is the reticular dermis made up of and how does it differ from the papillary dermis?
- dense irregular connective tissue
- papillary dermis: loose connective tissue
functions of the reticular dermis?
- provide strength and elasticity to skin
- contains important epithelial-derived structures, eg hair and follicles
what are the adnexal structures (epidermal appendages)?
- components of epidermal origin
- extend into dermis
1) pilosebaceous unit - hair follicle, sebaceous glands, arrector pili muscle
2) eccrine (in some areas apocrine) sweat glands
description of lesions according to color, shape, distribution, and location
- circumscribed change in skin color
- no elevation or depression
- large macule
- 1 cm or greater in diameter
lack of pigments
reddening of skin
- solid, elevated lesion
- 0.5 cm or less in diameter
- raised lesion
- greater breadth than height
- palpable solid lesion
- size varies, 0.5-2 cm in diameter
- may be present in dermis, epidermis or subcutaneous tissue
- rounded, flat-topped, elevated
- resulting from local edema
- circumscribed, elevated lesion
- contains fluid
- 0.5 cm or less in diameter
like vesicle but greater than 0.5 cm in diameter
- circumscribed elevated lesion containing pus
- abscess: dermis or subcutis
pustule = abscess?
abscess: pus in dermis or subcutis
- sac that contains liquid or semisolid material
- usually in dermis
heaping up of s. corneum or keratin
- occurs as a result of wetness
- skin becomes soft, white, and is susceptible to bacterial and fungal infections
- loss of epidermis above basal layer
- surface becomes denuded
- loss of epidermis and part or all of dermis
- depressed moist lesion
- linear cleft in epidermis or dermis
- focal loss of epidermis
- usually linear
define "crust" and give an example
- accumulation of blood, serum or purulent exudate
- infantile eczema
- accentuation of skin markings, associated with thickening of epidermis
- caused by scratching or rubbing
- fine papules are present
fibrous tissue which replaces normal skin after healing
atrophy (when pertaining to skin)
thinning of epidermis and/or dermis
what kind of appearance does atrophy cause and what is it called?
which lesions are primary ones? (9)
macule, patch, papule, plaque, vesicle (bulla), pustule, cyst, wheal, nodule
which lesions are secondary ones? (10)
scale, maceration, erosion, ulcer, fissure, excoriation, crust, scar, lichenification, atrophy
increased thickness of stratum corneum due to an increase of keratin caused by normal or abnormal keratinocytes
- keritinization in which keratinocytes retain their nuclei
- abnormal in skin, normal in mucus membranes
cell death due to premature keratinization below the stratum granulosum
- increase in keratinocytes in stratum spinosum (spinous layer) with thickening of epidermis
- papillomatous or psoriasiform
- increase in keratinocytes and formation of projections from skin surface, ie papillae
give a typical example for papillomatosis
- widening of interspaces between keratinocytes due to edema fluid
- no detachment of cells
give an example for ballooning degeneration
give an example for reticular degeneration
give an example for liquefaction degeneration of basal cells
give an example for acantholysis
give an example for munro's microabscess
give an example for kogoj's spongioform pustule
components involved in dermatologic diagnostics
history, PE, lab exams, special examinations, eg dermatographism, patch test...
sharply demarcated edema or wheal with surrounding erythematous flare seconds to minutes after stroking the skin
what is a patch test used for?
- used to detect hypersensitivity to a substance (ie allergen) coming into contact with skin
- allows determination of that allergen so the hypersensitivity can be treated
how is the patch test done?
- suspected allergen is applied to uninflamed, intact skin on a surgical pad or aluminium chamber, removed after 48 h (or earlier if necessary)
- evaluation: if hypersensitivity exists there may be certain skin lesions (ie erythema, papules, vesicles etc.). skin is evaluated after 48 h, day 4, 5 and 7
name the kinds theraphies used in dermatology (4)
what are topical drugs?
solutions, tinctures, powers, lotions, oils, emulsions, ointments, pastes, plasters, gels etc.
- dissolution of 2 or more substances into homogenous clarity
- the vehicle (base) may be aqueous, hydroalcoholic, or nonaqueous (alcohol, oils, propylene glycol)
give an example of a solution
3 % boric acid
hydroalcoholic solution with a concentration of about 50 % alcohol
give an example of a tincture
- absorb moisture and decrease friction
- adhere poorly to skin so use is restricted to cosmetic and hygienic purposes
2-phase system consisting of a finely divided, insoluble drug, dispersed into a liquid in a concentration of up to 20 %
lotions are also referred to as...?
- 2-phase systems involving 1 or more immiscible liquids dispersed in another with assistance of emulsifying agents
- water-in-oil emulsions (cream): contain less than 25 % water, oil is dispersion medium
- oil-in-water emulsions: contain more than 31 % water, aqeous phase may comprise up to 80 %
example of an emulsion