Composed of a single row of cuboidal or
Cells have an oval nucleus, prominent nucleoli, little heterochromatin (responsible for DNA/genes).
Have many mitochondria, free ribosomes, nuclei, may also have cytoskeletal filaments (actin
micro filaments and keratin filament bundles) and Tonofilaments.
Mitochondria - powerhouses of cell
Cytoskeletal - filaments -
give the skeleton to the cell
Tonofilaments - made up of keratin
converge together at the site of the
Some cells in this layer
are stem cells that
undergo cell division
continually produce new
Sits on basement membrane next to the dermis
Cells attached to the basement membrane by HEMIDESMOSOMES
Melanocytes and Merkel
cells - both are types of
MALPIGHIAN LAYER - ACTIVE/GROWING CELLS
Cells being made/cell growth
Consists of stratified squamous epithelium.
There is continuous replacement of cells. Renewed every 15-30 days.
Does not contain blood vessels - AVASCULAR
It is translucent.
The palms and soles are thicker
Cells of the Epidermis - Keratinocytes - 90% of epidermal cells. Melanocytes - 10% - found mainly in Basale layer.
Langherhans cells (dendritic cells) found in Spinosum layer - important in immune reactions. Merkel cells
(dendritic cells) are found in Basale layer - gather sensory information (touch). Form desmosomes with
Integumentum means COVER
4.5-5 Kilos - skin weight of a normal adult
2m2 - surface area of skin
0.5mm thick -eyelids to 5mm think - upper back.
We lose about 30-40k of cells every minute
19 million cells are in each square inch of human skin
32 million bacteria are found on each square inch of human skin
Langer's/Cleavage Lines - lines of
tension within the skin. Surgeons try
to follow when making incisions -
heaiing is faster and scarring is
The difference in pigmentation that
determines racial types is in the number of
MELANOSOMES, i.e. the organelle within
the melanocyte that produces pigment.
Disorders of Pigmentation: Albinism (involves a lack of Tyrosine), Vitiligo, Freckles