Skin

Front 1

Skin functions

Back 1

protective barrier
regulation of body temp
excretion of salts
vit d synthesis
sensory reception

Front 2

epidermis

Back 2

keritinized stratified squamous epithelium

Front 3

epithelial cells

Back 3

keratinocytes

Front 4

stratum basale (germinativum)

Back 4

highest cell proliferation
desmosomes between cells, hemidesmosomes anchor to basal lamina
lowests layer

Front 5

stratum spinosum

Back 5

spiny appearance due to cytoplasmic processes filled with keratin filament bundles
adjecent cellular processes connect by desmosomes

Front 6

stratum granulosum

Back 6

keratinosomes: complex hydrophobic glycophospholipids, released when cell dies, bind to keratin filaments and act as "cement", gooey substance
keratinohyaline granules: protein granules interact with keratin and cell membrane, helps make a waterproof barrier

Front 7

stratum lucidum

Back 7

loss of organelles, cells die, no nuclei

Front 8

stratum corneum

Back 8

acellular layer composed of compact "cement" keratin
regulated balance between cell proliferation and cell shedding (desquamation), cells in basal layer have high proliferation rate and being to synthesie keratine, cells stop dividing and accumulate keratin as they move up in epidermal layers until they are shed
thick skin vs thin skin
epidermal ridges
upper most layer

Front 9

melanocytes

Back 9

found in the lower layers, looks like octupi
derived from the neural crest
synthesize melanin which is stored in membrane-bound melanosomes (granules)
melanosomes are transported by microtubules to the cell process
exocytosed from the cell process and "injected" into keratinocytes in stratum basal and spinosum
keratinocyte lysosomes degrade them
melanin protects against non-ionizing UV irradation

Front 10

Melanin pigment depends on

Back 10

# of melanin granules synthesized
rate of transfer of melanin to keratinocytes
reaction with lysosomes

Front 11

Nevi

Back 11

localized benign melanocyte proliferation, can become dyplastic

Front 12

albinism

Back 12

problem with melanin synthesis

Front 13

UV light

Back 13

cause a point mutation in skin

Front 14

malignant melanoma

Back 14

radial growth has a better prognosis then vertical growth into deeper skin levels

Front 15

langerhans cells

Back 15

located in all layers of the epidermis, dendritic process extends between keratinocytes
act as antigen-presenting cells, facilitate uptake of microbial fragments
immune cell, paler looking

Front 16

merkel cells

Back 16

desmosomal attachments to keratinocytes
form synapses on peripheral nerves , believed to fcn as tactile receptors
act in sensory receoptin

Front 17

Dermis

Back 17

Papillary layer and reticular layer

Front 18

papillary layer

Back 18

Type VII collagen anchoring filaments to underlying cartilage
fibrillin molecules extend from papillary layer to elastic fibers in the reticular layer

Front 19

reticular layer

Back 19

dense irregular CT with elastic fibers, the fibrillin extends from the reticular layer into the papillary layer

Front 20

thermoregulatoin

Back 20

superficial and deep vascular plexi in dermis play a role in this, many atriovenous anastomoses (called glomus bodies) are located in the dermis (direct connection between arterioles and venuoles, blood bypasses the capillary bed)

Front 21

hypodermis

Back 21

subcutaneous fascia
looser CT, a lot of adipose, allows movement of skin overlying structures, lots of blood vessels

Front 22

hair follicle

Back 22

extension that is derived from the epidermis
hair bulb - produces hair shaft and internal root sheath
dermal papilla
hair shaft: medulla, cortex, cuticle
internal root sheath extends from bulb to level of sebaceous gland duct
external root sheath: modified epidermal layers, outermost layer is thick BM
outermost CT sheath encloses follicle and sebaceous gland, encases the whole business end

Front 23

sebaceous glands

Back 23

for most skin, duct opens hair follicle
eyelids, lips, areola, labia: ducts open onto surface epidermis
complex lipid secretion, low production until puberty

Front 24

sweat glands
Merrocrine (eccrine)

Back 24

over most of body
watery secretion with sodium chloride, potassium
coiled ducts, myoepithelial cells
assist in thermoregulation

Front 25

sweat glands
Apocrine

Back 25

perineum, anus, axilla
viscous secretion, triggered by external stimulus
modified apocirne glands:external ear, eyelids, areola

Front 26

arrector pilli muscles

Back 26

smooth muscle bundle, part of the viscerla structre in the skin

Front 27

sensory receptors

Back 27

free nerve endings in epidermis (pain, temp, tactile) in dermis and epidermis
merkel cells
meissner's corpusule
paccinian corpuscle
ruffini organs

Front 28

meissner's corpuscle

Back 28

tactile
encapsulated in papillary layer of the dermis
modified schwanna cells

Front 29

paccinian corpuscle

Back 29

pressure, encapsulated, hypodermis and dermis

Front 30

ruffini organs

Back 30

respond to stretch, dermis

Front 31

age related changes to skin

Back 31

collagen fibers thicken
decreased collagen synthesis
collagen fibers begin to crosslink
elastic fiber synthesis decrease

Front 32

hyperkeratosis

Back 32

an increased thickening of the stratum corneum and stratum granulosum, protective mech

Front 33

parakeratosis

Back 33

cells of corneum retain nuclei, normally occur in the oral cavity, may occur with some skin conditions

Front 34

acanthosis

Back 34

abnormal epidemal thickening, usually stratum spinosum
rete pegs = epidermal extensions into the papillary layer are abnormally long because of stratum spinosum proliferation
associated with chronic inflammatory conditions
hyper-pigmented patches

Front 35

intraepidermal edema

Back 35

varying degrees of fluid accumulation in the epidermis
form of vesicles and pustiles

Front 36

dermatitis

Back 36

acute or chronic
eczeme: inflammatory condition

Front 37

psoriasis

Back 37

chronic inflammatory condition caused by excessive proliferatoin of keratinocytes and accelerated upward migratoin
characterized by acanthosis and erythematous scaly white lesions
parakeratosis with microabsecc is epidermis
inflammation and angigenesis in dermis

Front 38

basal cell carcinoma

Back 38

invades dermis
most frequent areas exposed to sunlight
ususally benign

Front 39

squamous cell carncinoma

Back 39

tumors well demaracated and keratiinized
may invade dermis and regional lymph nodes