INTEGUMENTARY SYSTEM
Structure and Function
• Integumentary system is composed of the skin and
accessory structures (hair, hair follicles, nails, glands
& nerves)
• Functions of the integumentary system
– Protects the other body systems from injury and infection:
• Mechanical damage (cuts & bruises)
• Chemical damage (acids & bases)
• Thermal damage (heat & cold)
• Ultraviolet damage (sunlight)
• Defense against microorganisms
– Helps the body maintain homeostasis by regulating
temperature, retaining body fluids, and eliminating wastes
– Insulates and cushions deeper organs
Figure 9-1 Skin Structures
Skin
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The largest organ of the body
21 sq feet, 1.5 – 2 sq meters
4 kilograms, 9 pds, 7-15% of total body weight
Varies in thickness from 1/50 inch (0.5 mm) in the
eyelids to 1/4 inch (6.3 mm) in the soles of the feet
• Changes in the skin often indicate the presence of
other body system disorders including anemia,
respiratory disorders, liver disorders, cancer, and
shock
• Each inch of skin contains 15 ft of blood vessels
• The body sloughs off about 500 million cells a day; 1
½ pounds per year
Skin (cutaneous)
• The top layer is full of keratin and hardened
(cornified) to prevent water loss
• The rich capillary network and sweat glands help
regulate heat loss from surface
• It is a mini-excretory system- loses urea, water
and salts
• Manufactures proteins important to immunity and
synthesizes Vitamin A, D & K. (vit D synthesis
very important)
• Cutaneous sensory receptors
provide info about the
environment
Layers of Skin
• Epidermis
- it is avascular
– Outermost layer of the skin that is composed of a
surface of dead cells with an underlying layer of living
cells; complete regeneration appox 35 days and is
derived from the stratum basale layer
– Made up of stratified squamous cells that are capable of
keratinizing (hard/tough)
– Melanocytes (pigment cells); increase in sun exposure
will cause these cells to produce more melanin
– Langerhans cells: macrophages that activate the
immune system
– Merkel cells: sensory nerve receptors
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rights reserved.
Layers of Skin
• Dermis (corium or true skin)
– Called the “true” skin; the dermis contains the blood vessels
and nerves
– Dense Connective tissue; strong/flexible
– Collagen, elastin (stretch/recoil)
– Contains:
• Blood vessels and capillaries
• Lymphatic vessels
• Nerves
• Hair shafts and hair follicles
• Sensory receptors
• Sudorferous glands- sweat
• Sebaceous glands- oil
**The epidermis and dermis are firmly connected
but can be separated by friction
(blisters) Dense Connective tissue
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rights reserved.
Layers of Skin
• Subcutaneous- hypodermis
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Not skin
Adipose and areolar connective tissue
Stores fat
Anchors skin to underlying structures (muscles)
Allows skin to slide freely
Shock absorber, insulator
Thickens with weight gain
Types of Skin
• Thick skin- only on palms & soles
– Thick epidermis (.6-4.5mm) distinct stratum
lucidum & thick stratum corneum
– Lacks hair follicles & sebaceous glands
• Thin skin- covers most of the body
– Thin epidermis (.1-.15mm) lacks stratum
lucidum
– Lacks epidermal ridges, fewer sweat glands &
sensory receptors
Skin
• Stretch marks- extreme stretching that
produces a silvery white scar
• Blister- separation of epidermal and dermal
layers by fluid filled pocket
• Flexure lines- skin markings; dermal folds
at or near a joint; deep creases
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rights reserved.
Skin Color
• Pigments:
– Keratin
• Yellow to orange
• Accumulates in stratum corneum and fatty tissue of
hypodermis
• Color obvious in palms and soles
– Melanin
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Only pigment in the skin
Yellow to reddish-brown to black
Synthesis depends on enzyme in melanocytes
Racial differences vary on amount of melanin made
Local accumulation in freckles and moles
Exposure to sunlight increases manufacturing of melanin to
prolonged exposure; tan
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Abnormal color/homeostatic imbalances
• Pallor (blanching)
– Emotional distress, anemia, low BP
• Erythema (redness)
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Congestion of blood in vessels
Burns
Embarrassment (blushing)
Fever
Hypertension
Inflammation
Allery
Abnormal color/homeostatic imbalances
• Bruises
• Blood escapes and clots under skin, hematoma, vit c deficiency
• hemophilia
• Albinism
• Absence of pigment color
• Vitiligo
• Loss of pigment in certain areas, usually acquired
• Gray/Brown
• Chronic poisonings
• Cyanosis (blue)
• Insufficient oxygen
• Bronzing (metallic)
• Addison’s disease (hypofunction of adrenal cortex)
• Jaundice (yellow)
• Liver disorder, biliary disorder, presence of bile in blood,
diseases involving destruction of RBCs
Skin Injuries
• Excessive sun exposure
– Clumps elastin fibers “leathery skin”
– Temporary depression
of immune system
-DNA alteration (cancer)
Type 1- very fair
Type 2- tans minimally
Type 3- tans gradually
Type 4- medium skin
Type 5- rarely burns (dark)
Type 6- never burns (very dark)
Skin Injuries
• Blisters: injury damages chemical bond of
skin layers at dermal/epidermal junction
• Callous: abnormally thick stratum corneum
• Burns:1st, 2nd, 3rd & 4th degree depending on depth
of burn (UV light, corrosive chemicals, electricity)
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rights reserved.
Accessory Structures
• Hair/Hair
follicle
• Glands
• Nails
• Nerves
Hair and Hair Follicles
• Skin has hair in all areas except the soles of the
feet and palms of the hands
• Composed of keratin and proteins; also dead
epidermal cells
• Hair serves to block foreign particles from
entering the body through structures such as
the nose and eyes
• The visible portion is called the shaft
• The hair follicle is the root with its covering
– Anagen: growing follicle
– Telogen: resting follicle
Hair
• Growth:
– Lanugo: fetal hair and lost at birth
– Puberty: coarse hair; grows ½” per month
• Arrection Pili= hair muscles
– This is a tiny muscle that attaches to the base of a hair
follicle at one end and to dermal tissue on the other
end. In order to generate heat when the body is cold,
the arrector pili muscles contract all at once, causing the
hair to "stand up straight" on the skin. The arrector pili
muscle is a source of information when evaluating a
skin biopsy since it is well-innervated with autonomic
nerves that control when the muscle contracts.
Nails
• Tightly packed, keratinized cells
• Nail body is pink due to
– underlying capillaries
• Free edge appears white
• Lunula is white due to
– thickened stratum basale
• Cuticle (eponychium)
• Nail root- buried under skin layers
Glands
• Four types of glands in the skin
(exocrine)
– Sebaceous glands (oil)
– Sudoriferous glands (sweat)
– Ceruminous glands (wax)
– Mammary (milk) glands
• Function is to help regulate the body
temperature and excrete body wastes
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rights reserved.
Sebaceous (Oil) glands
• Secretory in dermis- open into hair shafts
• Acne- bacterial inflammation of glands
– Secretions stimulated by hormones at puberty
– Associated with blackheads
• Sebum- combination of cholesterol,
proteins, fats, and salts
– Keeps hair/skin soft and pliable
– Inhibits growth of bacteria and fungi
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rights reserved.
Sebaceous glands
Sudoriferous (sweat) glands
• Apocrine (sweat) glands- secrete at hair follicle and active at puberty
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In dermis with ducts that open into hair follicles
-Axilla (underarm)
Perianal (near the anal area)
Areole, (nipple)
Periumbilical (around the belly button),
External ear canal,
– Eyelids
– Also consists of ducts and secretory coils, but these glands are larger than
eccrine glands and open onto hair follicles.
• Eccrine (sweat glands)
– Most areas of the body
– In dermis with ducts to surface
– Regulates body temp w/ perspiration
*produces about 500 mL p/day
Sudorfierous glands
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rights reserved.
Ceruminous glands (wax)
• Modified sweat glands
• Located in auditory canal
• Cerumen- contains secretions of oil and
wax glands; barrier for entrance of foreign
bodies
• Impacted cerumen may reduce hearing
Disorders of the
Integumentary System
• Acne vulgaris
– Caused by increased secretion of oil related to
increased hormones during puberty
• Albinism
– Inherited disorder in which melanin is not produced
• Alopecia
– Baldness
• Athlete’s foot
– Contagious fungal infection of the foot
Disorders of the Integumentary
System (continued)
• Cellulitis
– Bacterial infection of the dermis and subcutaneous
layer of the skin
• Chloasma
– Patchy discoloration of the face
• Cleft lip or cleft palate
– Upper lip has a cleft where the nasal palate doesn’t
meet properly
• Contact dermatitis
– Allergic reaction that may occur after initial contact
or as an acquired response
Disorders of the Integumentary System
• Dandruff
– White flakes of dead skin cells from the scalp
• Decubitus ulcers (bed sores)
– Sores or areas of inflammation that occur over
bony prominences of the body
• Eczema
– Group of disorders caused by allergic or irritant
reactions; red, dry, itchy, scaly skin
• Fungal skin infections
– Skin infections that live on dead outer surface or
epidermis
Disorders of the Integumentary
System (continued)
• Furuncle
– Boil, or bacterial infection of a hair follicle
• Hirsutism
– Abnormal amount of hair growth in unusual places
• Impetigo
– Very contagious bacterial (staph or strep) skin
infection that occurs most often in children
• Kaposi’s sarcoma
– Form of cancer that originates in blood vessels and
spreads to skin
Disorders of the Integumentary System
• Lupus
– Benign dermatitis or chronic systemic disorder
• Psoriasis
– Chronic skin disorder in which too many epidermal
cells are produced
• Rashes
– May result from viral infection, especially in children
- Rhinoplasty- surgical repair of the nose
-Ring Worm
-Fungal infection on surface of skin; contagious and
treated with antifungal
• Scleroderma
– Rare autoimmune disorder that affects blood
vessels and connective tissues of the skin
*Tinea pedis -Athletes foot; fungal infection
Disorders of the Integumentary
System (continued)
• Skin cancer
– Three forms are basal, squamous, and melanoma;
**basal cell is most common
• Skin lesions
– Differ in texture, color, location, and rate of growth
• Streptococcus
– Nonmotile bacteria that affect many parts of the
body
Disorders of the Integumentary
System (continued)
• Vitiligo
– Condition that causes loss of pigment in the skin
• Wart
– Papule caused by a viral infection
Issues and Innovations
• Skin and hair care
– Skin care products include soap,
astringents, and cosmetics
– Ways to remove hair include wax,
depilatory creams, and electrolysis
• Sun and skin cancer
– Damage by ultraviolet rays
– Types of skin cancer
Warning Signs of Melanoma
-Change in size and pigmented spot or
mole
-Change in color of an existing mole
-Change in consistency of shape of the
skin over the pigmented spot
-Inflammation of the skin around an
existing mole
Melanoma