Skin - lecture 1

surface area of skin?

ca. 2 m^2

thin skin?

covers the greater part of the body

has hair, sweat- and sebaceous glands

also called hirsute

thick skin?

over fingertips, palmar- and plantar-surfaces

hairless, only sweat glands

also called glabrous

epidermis characteristics?

strat. keratinized sq. epithelium

no vessels

thickness varies in thin vs. thick skin

dermis characteristics ?

mechanical resistance

numerous papillae or rete ridges

glands and hair follicles

what are the parts of the skin?

epidermis + dermis

subcutis characteristics?

loose CT, fat pad

what are the skin appendages?

hair and nail

glands

layers of epidermis?

str. basale/germinativum

str. polygonale/spinosum

str. granulosum

str. lucidum

str. corneum

which layer of the epidermis is absent in the thin skin?

str. lucidum

what are the parts of str. corneum?

str. compactum

str. disjunctum

which layers of the epidermis make up the malpighi layer?

str. basale

str. polygonale

what are the cell types of the epidermis?

keratinocyte

melanocyte

langerhans cell

merkel cell

keratinocytes characteristics?

90 %

basally: living cells, superfically: dead keratinized cells

str. basale characteristics?

mitotic activity

prickle cells?

desmosomes w. tonofilaments

str. granulosum characteristics?

profilaggrin providing clumping of tonofilaments in keratohyalin granules

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release of extracellular lipids from lamellar bodies

str. corneum characteristics?

filaggrin (matrix) + keratin filaments → keratin

cell lack nucl.

cornified envelope - involucrin protein

cornified lipid envelope - ceramide

physiological epidermal turnover time?

52-75 days

epidermal turnover time in case of psoriasis?

8 days

langerhans cell characteristics?

part of the mononuclear-phagocyte system

antigen presenting cell

melanocyte characteristics?

most are clear as melanosomes are transferred to the keratinocytes by cytocrine secretion

what stimulate transfer of melanosomes to keratinocytes?

UV-radiation

TNF-alpha

ACTH

alpha-MSH

characteristic of melanosomes in darker skin?

larger and lies more superficially

what are the molecular anchorage in the dermo-epithelial junction?

1. tonofilaments - desmosomes
2. basal cells - lamina densa - hemidesmosomes
3. anchoring fibrils of type VII collagen bind lamina densa to collagen fibers (type III) in papillary dermis


1. microfibrils link the elastic fibers to collagen fibers

layers of dermis?

papillary layer

reticular layer

papillary layer characteristics?

loose CT

fine collagen fibers (type 1 and 3)

capillary loop, nerve endings, meissner’s corpuscle

reticular layer characteristics?

dense CT

thick collagen fibers - type 1

elastic fibers

smooth muscles in some cases, such as tunica dartos of penis and scrotum

what are the langer’s lines?

long axis of rhomboids that frequently coincide w. relaxed skin tension lines

what do the dermal papilla create?

friction ridges → fingerprint

characteristics of subcutis (hypodermis)

loose (adipose tissue) CT → mediates increased mobility of skin

function of panniculus adiposus?

shock absorber, energy store, thermal insulation

function of retinaculum cutis?

strong binding to underlying tissues in certain areas of the skin

what are the glands of the skin?

sebaceous

sudoriferous

odoriferious

characteristics of sebaceous glands?

holocrine

branched alveolar

open into hair follicles usually, sometimes skin surface: lips, inner surface of prepuce, minor labia, glans of penis/clitoris, areola/nippels

missing in sole and palm

characteristics of sudoriferous glands?

merocrine

simple coiled tubular

open onto skin surface

missing in: lips, inner surface of prepuce, minor labia, glans of penis/clitoris

cholinergic symp. innervation

characteristics of odoriferous glands?

apocrine

simple coiled tubular

open into hair follicles of: axillary, areolar and anal genital regions

adrenergic symp. innervation

function of arteriovenousus anastomoses?

prevent heat loss

what are the plexuses found in the skin?

superficial (sub papillary) plexus

mid-dermal venous plexus

deep (subdermal) plexus

what are dermatomes?

cutaneous areas supplied by one spinal nerve

what are the functions of the skin?

receptor organ

mechanical and chemical protection

thermoregulation

photoprotection

permeability barrier

protection against pathogens

what do the germinal matrix cell differentiate into?

medulla

cortex

cuticle

inner root sheath

layers of hair?

medulla

cortex

cuticle

what surrounds the hair root?

hair follicle

layers of the hair follicle?

inner root sheath

outer rooth sheath

glassy membrane

CT sheath'

function of hair?

thermoregulation

protection against UV radiation

sensory function

chemotherapy effect on hair?

harmfull effects on matrix cells or on their blood supply, rupture of hair root

which hormone induces hair loss? which phase is shortened?

androgen (DHT)

anagen phase

what are the phases of the hair cycle?

anagen

catagen

telogen

return to anagen

what is the dermis of the nail bed anchored to?

periosteum

which layer is not found under the nail?

subcutis