Integumentary System

Skin Trivia

• 22 Square Feet• 8-10 pounds, 7% - 15% of Total Body

Weight• Complex Combination of Tissues• Continuous Layer• Skin & accessory structures (hair, nails, &

glands)• Integument = covering

One Square Inch Contains

• 20 Blood Vessels• 65 Hairs & Hair Muscles• 78 Nerves• 78 Sensors for Heat• 13 Sensors for Cold• 160 Sensors for Pressure

• 100 Sebaceous/Oil Glands

• 1300 Nerve Endings• 19,500,000 Cells• 0.5 Million Cells Dying &

Being Replaced

Functions

• Protective membrane• Guards the deeper tissues

• Against water loss, salts, heat, & invasion of pathogens

• Produce important secretions• Sebaceous glands

• Produce sebum (oily secretion)• Lubricates the surface of the skin

• Sweat glands• Produce sweat

• Cools the body as it evaporates from the skin

Layers/Regions of the Skin

• Epidermis: • Most Superficial

• Dermis: • Tough, Leathery Fibrous Connective Tissue; Only

Part Vascularized• Subcutaneous (Hypodermis):

• Superficial Fascia; Mostly Fat (Insulate & Absorb Shock); Anchors Skin to Underlying Structures

Epidermis

• Outer layer of stratified squamous epithelial tissue• Squamous epithelial cells are flat & scale-like

• Arranged in several layers (strata) forming stratified squamous epithelium

• Avascular• Dependent on deeper dermis for nourishment

• Complete regeneration every 35-45 days• Thinner on scalp and armpit than on sole of foot

Layers of the Epidermis

• Basal layer (Stratum Basale/Stratum Germinativum)• Deepest layer• Actively dividing to replace old cells• Single row of cells (mostly stem cells)• 10-25% = melanocytes (secrete melanin)

• Stratum Spinosum• Spiny layer, Several cell layers thick• Mostly Langerhans cells surrounded by keratinocytes

with spiny projections (prickle cells)

Layers of the Epidermis• Stratum Granulosum

• Keratohyaline granules formation of keratin• Water resistant layer

• Slows water loss from body

• Receives nutrients from tissue fluids

• Stratum lucidum• Clear layer, Absent in thin skin• Thickest in soles of feet and palms

Layers of the Epidermis

• Stratum corneum• Horny layer• Outermost layer• Mostly dead keratinocytes or keratin filled plasma

membrane sacs• 20 – 30 cell layers thick• ¾ of epidermal thickness• Protect against abrasion and penetration• Glycolipid = waterproof coat• Protects deeper cells• Dandruff = dry skin shedding = 40 pounds in lifetime• Hyperkeratosis: thick dry scaly skin

Dermis• Characteristics

• Strong, flexible connective tissue• Hide of the skin• Collagen, elastin (stretch-recoil), reticular fibers

• Colla = glue• Wrinkling of elderly = loss of elastin and subcutaneous fat

• Contents• Blood vessels• Nerves• Hair shafts & hair follicles

• (anagen = growing follicle, telogen = resting follicle)

• Arector pili (hair muscles)• Sebaceous & Sweat glands

Subcutaneous Layer

• Specializes in the formation of fat• Adipocytes (fat cells)

• Predominant; manufacture & store large quantities of fat

• Protects deeper tissue• Heat insulator• Energy storage

Accessory Structures of the Skin• Hair

• Tightly fused meshwork of cells filled with keratin (protein)• Hair root

• Produce keratinized cells that move through Hair follicles• Melanocytes

• Located at the root, responsible for pigment• Melanin containing iron = red hair• Stop producing = gray hair

Accessory Structures of the Skin

• Nails• Keratinized/dead epidermal

cells • Grows under the lunula

(white portion) of nailbed• Cuticle – narrow band of

epidermis• Paronychium – soft tissue

surrounding the nail border

• Glands• Sebaceous Glands

• Located in the dermal layer over the entire body• Exception of palms, soles, & lips

• Secrete sebum (contains lipids)• Closely associated with hair follicles

• Sweat Glands• Eccrine sweat glands (most common)

• Cover most of your body and open directly onto the surface of the skin. Most numerous in the palms & sole of the foot

• Apocrine sweat glands – active from puberty onward (mammary gland is a type of apocrine gland)

• develop in areas abundant in hair follicles• such as on your scalp, armpits and groin and open into the hair

follicle just before it opens onto the skin surface. • Secrete an odorless sweat - Bacteria breaking down sweat

produces human body odor

Pathology Cutaneous Lesions (Lesion = abnormal tissue)

a) Crust – collection of dried serum & cellular debris (scab)

b) Cyst – thick-walled, closed sac containing fluid or semisolid material

c) Erosion – wearing away or loss of epidermis

d) Fissure – groove or crack-like sore

Pathology Cutaneous Lesions

e) Macule-Flat lesions (freckles, tattoo

marks, flat moles)

f) Nodule-Solid, round/oval elevated lesion

g) Papule-Small, solid elevation(pimple)

h) Pustule-Papule containing pus

i) Ulcer-Open sore on the skin (decubitus

ulcers – bedsores)

Signs & Symptoms • Alopecia

• Absence of hair from areas where it normally grows

• Ecchymosis• Bluish-purplish mark (bruise) on

skin• ec- = out, chym/o = pour

• Hemorrhages into the skin

• Petechia • Small, pinpoint hemorrhage

• Pruritus• Itching

Abnormal Conditions

• Acne• Chronic papular & pustular eruption

of the skin with increased production of sebum

• Burns• 1st degree

• Superficial epidermal lesions• 2nd degree

• Epidermal & dermal lesions, blisters (partial-thickness burn injury)

• 3rd degree• Necrosis of skin (epidermis & dermis

destroyed) & subcutaneous layer damaged (full-thickness burn injury)

Abnormal Conditions• Cellulitis

• Acute infection of the skin marked by local heat, redness, pain & swelling

• Eczema• chronic skin disorder that

involves scaly and itchy rashes

• Gangrene• Death of tissue associated with

loss of blood supply

• Impetigo• Bacterial disease characterized

by vesicles, pustules, & crusted-over lesions

Abnormal Conditions• Psoriasis

• Chronic, recurrent dermatosis marked by itchy, scaly, red plaques covered by silvery gray scales

• Scabies• Scabies is an easily spread

skin disease caused by a very small species of mite.

• Tinea• Infection caused by a fungus

• Vitiligo• Loss of pigment

Cancerous Lesions• Basal cell carcinoma

• Malignant tumor of the basal cell layer of the epidermis

• Squamous cell carcinoma• Malignant tumor of the squamous epithelial cells in the

epidermis

Cancerous Lesions

• Malignant melanoma• Cancerous growth composed of melanocytes

Audionyms

Cau-, caus

• Audionym• Cough

• Visual Image• See the COUGH the

BURNS

• Meaning• burn

Cryo-

• Audionym• Cry

• Visual Image• See the baby CRYing

because it is cold

• Meaning• Cold

Cyan(o)

• Audionym• Sign

• Visual Image• See the stop SIGN

with BLUE paint poured on it

• Meaning• blue

Dermat-, -derm

• Audionym• Doormat

• Visual Image• See the DOORMAT

made of SKIN

• Meaning• skin

Helio-

• Audionym• Heel

• Visual Image• See the HEEL made

out of a LIGHT

• Meaning• Sun, light

Hydr(o)-

• Audionym• Hydrant

• Visual Image• See the HYDRANT

with WATER gushing out

• Meaning• water

Kerat-

• Audionym• Carrot

• Visual Image• See the CARROT

being used as HORNS

• Meaning• Horny, horny tissue,

cornea

Leuk(o)

• Audionym• Look (magazine)

• Visual Image• See the LOOK

magazine which is all WHITE

• Meaning• white

Lip-

• Audionym• Lip

• Visual Image• See the LIP which is

very FAT• Meaning

• Fat

Melan-

• Audionym• Melon

• Visual Image• See the MELON with

the BLACK seeds inside

• Meaning• black

Myco-

• Audionym• My coat

• Visual Image• See MY Coat covered

in FUNGUS

• Meaning• fungus

Onych-

• Audionym• onyx

• Visual Image• See the black ONYX

on the NAIL

• Meaning• Nail, claw

Pilo-, tricho-

• Audionym• Pile of

• Visual Image• See the PILE OF

HAIR

• Meaning• hair

Sub-• Audionym

• Submarine• Visual Image

• See the SUBmarine UNDER, BENEATH, or BELOW the water

• Meaning • Under, beneath, below

Therm-

• Audionym• Thermometer

• Visual Image• See the people around

the THERMometer as it generates HEAT

• Meaning• heat

Xer-

• Audionym• Zero

• Visual Image• See the 7up ZERO that

has a DRY taste

• Meaning• dry