SKIN AND BODY MEMBRANES
THE SKIN

Fun Facts:

Avg. makes up about 9-11 lbs. or 7% of your weight

Regenerates every 25-45 days

Every minute you lose 30,000-40,000 dead skin cells
SKIN STRUCTURE (EDH)

Epidermis (epithelial)
Dermis (fibrous)
Hypodermis (subcutaneous – fat)
SKIN STRUCTURE (EDH)
SKIN STRUCTURE

Epidermis—outer layer

Stratified squamous epithelium
SKIN STRUCTURE

Dermis

Dense connective tissue
Not part of the skin
 Anchors skin to underlying organs
 Mostly adipose tissue (subcutaneous tissue)

5 LAYERS OF THE EPIDERMIS (CLGSB)

Stratum corneum

Statum lucidum

Stratum granulosum

Stratum spinosum

Statum basale
5 LAYERS OF THE EPIDERMIS (CLGSB)

Stratum basale
5 LAYERS OF THE EPIDERMIS (CLGSB)

Stratum spinosum
5 LAYERS OF THE EPIDERMIS (CLGSB)

Stratum granulosum
5 LAYERS OF THE EPIDERMIS (CLGSB)

Stratum lucidum
5 LAYERS OF THE EPIDERMIS (CLGSB)

Stratum corneum
NOTE:


Thick skin- covers palms, fingertips, soles of
feet
Thin skin – covers rest of body

missing stratum lucidum and sometimes stratum
granulosum
MELANIN


Pigment produced by melanocytes
Amount of melanin produced depends upon
genetics and exposure to sunlight
MELANIN – SKIN COLOR

GENETICS is the key factor
 Quantity
of melanin
(yellow to reddish- brown to black)
 protects skin from UV radiation


Melanocytes use enzyme tyrosinase to convert
tyrosine into dark brown melanin pigment,
albinos lack DNA code to make tyrosinase
ALBINISM IN HUMANS
MELANIN – SKIN COLOR



Sunlight increases
melanin production by
the release of
hormones
freckles or moles are
accumulations of
melanin
other pigments such as
carotene or
hemoglobin contribute
to skin color
MELANIN – SKIN COLOR

Prolonged exposure
causes substantial melanin
buildup which helps
protect the DNA of viable
skin cells from UV
radiation by absorbing the
light and dissipating the
energy as heat
DERMIS

Two layers

Papillary layer (upper dermal
region)

Reticular layer (deepest skin
layer)
DERMIS

Papillary layer (upper
dermal region)
DERMIS

Reticular layer (deepest
skin layer)
DERMIS OVERVIEW



Collagen fibers give
skin its toughness
Elastic fibers give skin
elasticity
Blood vessels play a role
in body temperature
regulation
SKIN APPENDAGES
Glands
 Hair
 Hair follicles
 Nails

SEBACEOUS GLANDS

Produce oil

Glands are activated at puberty
SEBACEOUS GLANDS
SWEAT GLANDS

Produce sweat

Widely distributed in skin

Two types
Eccrine
 Apocrine

SWEAT GLANDS
HAIR
Produced by hair follicle
 Consists of hard keratinized epithelial cells
 Melanocytes provide pigment for hair color

HAIR


Hair follicle- shaft, follicle
(root)
Growth- 4 in./year or 2
mm/week
HAIR

Associated hair structures

Hair follicle

Arrector pili muscle

Sebaceous gland

Sweat gland
NAILS

Scale-like modifications of the epidermis
NAILS
 Consists
of:
free edge
 Body
 Root
 Cuticle
 Lunula

 Growth-
0.5 mm/week
NAILS
NAILS


Did you know that your fingernails grow much
faster than your toe nails?
3-4 times faster!
SKIN INFECTIONS AND ALLERGIES

Contact dermatitis


Cold sores


Caused by virus
Impetigo


Exposures cause allergic reaction
Caused by bacterial infection
Psoriasis
Cause is unknown
 Triggered by trauma, infection, stress

SKIN INFECTIONS AND ALLERGIES
BURNS

Burns

Tissue damage and cell death caused by heat,
electricity, UV radiation, or chemicals
BURNS

Associated dangers
RULE OF NINES

Way to determine the extent of burns

Body is divided into 11 areas for quick estimation

Each area represents about 9% of total body
surface area
RULE OF NINES
SEVERITY OF BURNS

First-degree burns

Second-degree burns

Third-degree burns
SEVERITY OF BURNS
CRITICAL BURNS

Burns are considered critical if
Over 25% of body has second-degree burns
 Over 10% of the body has third-degree burns
 There are third-degree burns of the face, hands, or
feet
