Skin - integument, cutaneous membrane
 Regulate body temperature
 Blood reservoir
 Protect from external environment
 Sensation to stimuli
 Excretion & absorption
 Vitamin D synthesis
Epidermis - outer epithelium
 Keratinocytes - horn-like, tough cells
to protect.
 Melanocytes - protect from UV
exposure, responsible for tanning.
Dermis - deeper, germinal connective
tissue
Hypodermis - not skin tissue
Areolar & adipose tissue
Epidermal layers
 Stratum basale
 Stratum spinosum
 Stratum granulosum
 Stratum lucidum
 Stratum corneum
Dermis
Dermal papillae - undulating upper
portion of dermis
 Meissner corpuscles - touch
receptors
 Free nerve endings - hot/cold, pain,
tickle, itch.
Photodamage
UVB can damage DNA in epidermal
cells, resulting in skin cancer.
Tanning is a response to tissue damage
as melanin granules spread from clumps
to cover more cells.
Skin color - normally translucent, color
determined by melanin, carotene, &
hemoglobin.
 Melanin - amount determines skin
tone. May collect as freckles or liver
spots.
 Carotene - yellow/orange pigment in
stratum corneum & fat.
 Hemoglobin - red pigment in blood
that causes white people to appear
pink.
Albinism - absence of melanin
Vitiligo - loss of melanocytes in patches
= white spots.
Cyanosis - "blue" color to the skin due
to oxygen depletion.
Jaundice - "yellow" skin color due to
bilirubin in the blood from impaired liver
function.
Erythema - "red" skin due to flooded
capillaries from heat, infection, infection,
or allergic reaction.