Credits: Jessica Brual

1. Epidermis
the outermost layer of the skin

2. Epidermis
• "epi" in Greek meaning "over" or "upon"
• serves as a barrier to protect against microbial
pathogens, oxidant stress(UV light) and
chemical compounds and provides mechanical
resistance.
• it protects the body from a possible injuries.

3. Parts of Epidermis
• Stratum Corneum (Horned Layer)
-to form a barrier to protect the underlying tissue
from infection, dehydration, chemicals.
-this layer is responsible for the "spring back" or
stretchy properties of skin. A weak glutenous
protein bond pulls the skin back to its natural
shape.
- contains 20 layers of dead cells.
-it is permanent and is replaced only during times of
rapid growth, in a process called ecdysis or
moulting.

5. • Stratum Lucidum (Clear Layer)
-is a thin, clear layer of dead skin cells in the
epidermis named for its translucent under the
microscope.
-it is readily visible by light microscopy only in areas
of thicker skin, which are found on the palms of
hand and the soles of the feet.
-they are flattened. They are sorrounded by an oily
substance that is the result of the exocytosis of
lamellar bodies accumulated while the
keratinocytes are moving through the stratum
spinosum and stratum granulosum.

7. • Stratum Gronulosum (Granular Layer)
– is a thin layer of cells in the epidermis.
Keratinocyte migrating from the undelying
stratum spinosum become known as granular cells
in this layer, This cells contain keratolyalin
granules, which are filled with proteins that
promote hydration and crosslinking of keratin.
Keratinocytes
-is the formation of barrier against environment
damage such as pathogens, heat, UV radiation
and water loss.

9. • Stratum Spinosum
-this layer is also reffered to as the "spinous" or
"prickle-cell" layer.
-this layer is composed of polyhedral keratinocytes,
they have large pale staining nuclei as they are
active in synthesizing fibrils proteins, known as
cytokeratin, which build up within the cells
aggregating together forming tonofibrils.The
tonofibrils go on to form the desmosomes
allowing strong connections to form between
adjacent keratinocytes.

11. • The stratum basale
– is primarily made up of basal keratinocyte cells,
which can be considered the stem cells of the
epidermis. They divide to form the keratinocytes
of the stratum spinosum, which migrate
superficially. Other types of cells found within
the stratum basale are melanocytes (pigment-
producing cells), Langerhans cells (immune cells),
and Merkel cells (touch receptors).
– the stratum basale (basal layer, sometimes
referred to as stratum germinativum) is the
deepest layer of the five layers of theepidermis,
which is the outer covering of skin in mammals.