Integumentary System
Dr. Karen Coker
Tennessee State University
SKIN
Skin reflects one’s personality and character
Much can be learned just by looking at an
individual’s skin
SKIN
• Wrinkles indicate mood, age, social habits,
overexposure to the sun
Skin Tone
• Color reflects one’s ethnicity as a result of the
melanin content
Melanocyte
Skin Texture
• The skin’s texture
indicates one’s life
occupation from
repeated mechanical
forces or weather
exposure
Reflects Emotion-gestures
• Skin reflects one’s
emotions as it moves
fluidly with the
underlying muscles and
connective tissue.
SKIN
• Skin abnormalities can be a response to a
disease process, injury, allergy, or medication
Contact Dermatitis from a silver watch band
http://www.iacdworld.org/skin/contact.htm
Wounds
• Skin wounds that are partial thickness heal
with skin
• Skin wounds that are full thickness heal with
scar tissue
Skin-Two Distinct Layers
• Epidermis and dermis
• Largest organ
• Functions
– Temperature regulation
– Excretion of sweat and
electrolytes
– Oil secretion
– Vitamin D synthesis
– Sensation
Skin-Two Distinct Layers
• Epidermis
– Outermost layer
– Waterproof
– Protects body from
infection
Skin-Two Distinct Layers
• Dermis
– Contains nerves, vessels,
lymphatics, elastic fibers,
sweat and sebaceous
glands, hair follicles
– Contains collagen fibers
that give skin its strength
and elasticity
Skin
• Subcutaneous tissues and
fat
5 layers to the epidermis
•
•
•
•
•
Stratum corneum-dead cells that shed
Stratum lucidum-soles and palms (thickness)
Stratum granulosum
Stratum spinosum
Stratum basale-produces epidermal cells
Cell adherence
• Epithelium:
– Cells bind the skin cells
to each other
– Cells bind the stratum
basale of the epidermis
to the dermis
Dermal-epidermal Junction
• Dermal papillae and
epidermal pegs meet
together to create a
bond that will
withstand friction and
shear forces to the skin
Sensation
Informative
• Skin has sensors that pick
up information and send
that information to the
brain
Protective
• If the skin senses danger or
pain, a quick reflex to move
away from the pain protects
you from further injury
Skin Renewal
• New skin cells (keratinocytes) are located in
the epidermis in the stratum basale
• If skin needs to heal, the fibroblasts in the
dermis are the major cells involved
Prevention of fluid loss
• The outer most layer of the epidermis is the
stratum corneum
• It is a barrier to fluid loss
• Homeostasis (balance) is maintained
• Water loss can cause dry skin or irritant
dermatitis
Immunity
• In addition to the physical barrier skin
provides,
– Langerhans cells (stratum spinosum in the
epidermis: are alerted by foreign microbes that
come on the skin)
– pH (acidic pH of 4.2-6 that is an “acid mantle” for
a chemical barrier to microbes)
– Antimicrobial peptides and lipids (prick the
microbe cell membrane and destroy its integrity,
making it inactive)
Thermoregulation
• Skin responds to changes in temperature
– Dermal blood vessels:
• arteries constrict when cold to preserve inner body
heat
• In heat, arteries dilate to allow more blood to circulate
near the skin surface and dissipate the heat
– Sweat glands
• Eccrine sweat glands allow fluid to evaporate
– (apocrine sweat glands are stress related: armpits, groin)
Protection from Ultraviolet Rays
• Presence of melanin
– Provides color variation
– Provides protection of underlying tissue from the
UV rays of the sun
Synthesis and Storage of Vitamin D
• Vitamin D is necessary for calcium metabolism
and bone formation
• Stratum basale and stratum spinosum have
keratinocytes that secrete Vitamin D
• Process is stimulated by sunlight
– At least 10 min per day is recommended
Aesthetics and Communication
• Appearance and sexual attraction
– Skin color
– Texture
– Hyper/hypopigmentation
– Apocrine sweat glands in the armpit and groin are
dependent on sex hormones and they secrete sex
pheromones that can influence behavior
Wound Healing
• Primary Intention: incision is sutured or fibrin
glued or staples back together
– Delayed primary intention: wounds left open a few
days, then sutured
• Secondary Intention: healing by letting it close on
its own: inflammatory response, granulation
tissue formation, re-epithelialization
• Partial thickness wounds: epithelial cell mitosis
and migration
Wound Healing
• Hemostasis: blood clot formation (6-12 hours)
• Inflammation (1-7 days)
– Invaders killed
– Wound debridement
– Neo-angiogenesis
• Proliferation (6 days-8 weeks)
• Maturation/Remodel (2 weeks -2 years)
Hemostasis: blood clot formation
(6-12 hours)
Inflammation (1-7 days)
Proliferation (6 days-8 weeks)
Eschar
(needs debridement)
Neo-genesis
Proliferation
Maturation/Remodel (2 weeks -2
years)
• Re-epithelialization of a wound: skin cells
grow over the granulation tissue to seal the
wound
Reference
• Text and Atlas of Wound Diagnosis and
Treatment by Rose L Hamm. 2015. McGrawHill Education.