LAYERS OF SKIN

The Layers of Skin

HypodermisDermis

Epidermis

EPIDERMIS- made up of stratified

squamous epithelium that is capable of keratinizing

(becoming hard and tough)

The Blood Supply of the EpidermisThe epidermis is

AVASCULAR.Convenient? YES!

When we shave, we cut off many cell layers and

do NOT bleed!

Keratinocytes Melanocytes• Keratin cells that PRODUCE

KERATIN.• THE FIBROUS PROTEIN THAT

MAKES THE EPIDERMIS A TOUGH PROTECTIVE LAYER

• A PIGMENT THAT RANGES IN COLOR FROM YELLOW TO BROWN TO BLACK.• SPECIAL SPIDER SHAPED CELLS• PRODUCE MELANIN• Freckles and moles are seen

where melanin is concentrated in one spot.

Layers of the EpidermisStratum Corneum- the outermost layer

- Accounts for ¾ of the epidermal thickness

- Completely filled with keratin (provides a durable “overcoat” for the body which protects deeper cells from water loss and resist biological, chemical, and physical assaults.

Layers of the EpidermisStratum Corneum

-Rubs and flakes slowly and steadily as dandruff

-Dandruff provides a food source for dust mites that live in our homes and linens

- Layer is replace by the stratum basale cells. We have a totally “NEW” epidermis every 25-45 days

Layers of the EpidermisStratum Lucidum

-Not present in all skin regions-Occurs only where skin is hairless and extra thick (PALMS and SOLES)

-They are unable to receive an adequate blood supply

-Consists of the dead cells from the Stratum Spinosum and Granulosum

Layers of the EpidermisStratum Granulosum and

Spinosum-Receive daughter cells from

the Stratum Basale-Consist of flat cells full of

keratin

Layers of the EpidermisStratum Basale

- A.K.A: Stratum Germinativum- Deepest layer- Lies closet to the dermis- Connected along a wavy borderline- Contains epidermal cells that receive the

most adequate nourishment via diffusion of nutrients from the dermis.

- Cells are constantly undergoing CELL DIVISION

Dermis-Made up of mostly dense connective tissue

-The majority of leather goods you buy

-Varies in thickness (thicker on palms and soles – thin on the eyelids)

Dermis: Collagen and Elastic FibersBoth are found throughout the dermis

Collagen Elastic• Responsible for the toughness

of the dermis• Attract and bind to water

(helps keep the skin hydrated)

• Give skin its elasticity when we are young• As we age, they decrease in

number, and the subcutaneous layer loses fat. As a result, the skin loses its elasticity and begins to sag and wrinkle.

Blood Supply of the Dermis• Abundantly supplied with blood• Blood vessels play a role in

maintaining body temperature homeostasis

Nerve Supply of the DermisMany of the nerve endings in this

area have specialized receptor end organs and send messages to the

central nervous system for interpretation.

Papillary Layer Reticular Layer• Upper dermal region• Has peg-like projections from its

superior surface (dermal papillae) which indents the epidermis above

• Many contain capillary loops which furnish epidermis with nutrients

• Others house pain and touch receptors called Meissner’s Corpuscles

• Hands and Palms• Papillae are arranged in patterns

to form loops and swirls that are genetically determined (fingerprints)

• Increase friction and gripping ability in the area.

• Deepest skin layer• Contains blood vessels,

sweat and oil glands, and deep pressure receptors (Pacinian Corpuscles)• Contain phagocytes that act

to prevent bacteria that have managed to get through the epidermis from penetrating deeper into the body.

HYPODERMIS•AKA Subcutaneous Tissue•Mainly composed of adipose tissue•Not considered part of the skin•Anchors the skin to underlying organs•Serves as a shock absorber and insulates deeper tissues from extreme temperature changes

Man vs. Woman

Hypodermis is responsible for the curves of women more

than men