Summary The Ingumentary System

The Ingumentary System
SKIN Layers of the Epidermis
Roles of Skin  Stratum Corneum
(outermost)
 Protection and immunity
 Many sublayers of flat,
 Sensation
dead keratinocytes,
 Thermoregulation
continuously shed,
 Excretion and absorption
replaced by cells from
 Synthesis of Vitamin D
deeper strata
 Storage
 Stratum Lucidum
Skin Structure  Present only on thick
skin (fingertips, palms
Three major layers and soles)
 Epidermis  Transparent
 Outermost  Stratum Granulosum
 Thinner layers  Includes keratohyalin
 Dermis (cytoplasmic granules
 Bellow epidermis – promote
 Thicker layer dehydration, cross-
 Hypodermis linking of keratin
 Bellow the dermis fibres)
 Attaches skin to  Cells die in this layer
underlying tissue and  Stratum Spinosum
organs  8-10 layers of
keratinocytes with
desmosomes,
intracellular bridges
(“prickles”)
 Stratum Basale
 Deepest layer
 Continuous cell
division occurs
producing all other
layers-stem cells
Epidermis
Cells of the epidermis
 Keratinized stratified
 Keratinocytes (90% of cells)
squamous epithelial cells
 Produce keratin
 Avascular
(tough fibrous protein
 Multilayered, flexible, self-
that provides
repairing barrier
protection)
 Prevents fluids loss
 Melanocytes (8% of cells)
 Protects from UV radiation
 Produce melanin
 Produces vitamin D3
pigment (protects
 Resists abrasion, chemicals
against damage by
and pathogens
ultraviolet radiation)