The Skin in Health & Disease

Chapter 6

outline• Structure of the skin

– Epidermis• Stratum basale• Stratum corneum

– Dermis– Hypodermis

• Accessory structure of the skin– Glands

• Sebaceous (oil) glands• Sudoriferous (sweat) glands

– Eccrine– apocrine

– Hair – Nails

• Functions of the skin

• Observation of the skinColor

pigmentdiscoloration

Lesionssurfacedeeper

Burns• Tissue repair• Skin aging• Care of the skin• Skin disorders

Integumentary System• Skin and associated

structures form integumentary system

• A membrane enveloping the body

• Accessory structures aka appendages– Glands– Hair – nails

• Consists of two layers:– Epidermis – outer layer.

Subdivided into thin layers called strata. Composed entirely of epithelial cells, no blood vesseles.

– Dermis – “true skin”. Framework of connective tissues and contains: Blood vessels, nerve endings, and glands

I. Structure of the Skin

a. Epidermis• Outermost surface of skin• Avascular – nourished by capillaries in underlying

dermis• In the deepest layer, Stratum basale or stratum

germinativum, new cells are produced and pushed upward

• As the cells die, their cytoplasm is replaced by protein called keratin which tickens and protects the skin forming the upper layer of epidermis, stratum corneum

• Exfoliation – the constant loss and replacement of cells

b. Dermis – “True Skin”

• Framework of elastic connective tissue• Extensive blood & nerve supply• Most appendages in the dermis• Dermal papillae – extensions into the

epidermis to allow for increased blood supply to the epidermis– Distinct ridge pattern which also help for grip– Basis of fingerprints & footprints

Dermal Papillae

Checkpoint 6-1: The skin and all its associated structures comprise a body system. What is the name of this system?

Checkpoint 6-2: The skin itself is composed of two layers. Moving from the superficial to the deeper layer, what are the names of these two layers?

c. Subcutaneous Layer - Hypodermis

• Connects skin to surface muscles

• Composed of areolar & adipose tissue

• Connected to dermis with continuous bundles of elastic fibers

• Rich blood and nerve supply

• Glands– Sebaceous

(oil) glands– Sudoriferous

(sweat) glands

• Nails • Hairs

II. Accessory Structures of Skin

a. Sebaceous (Oil) Glands• Saclike exocrine

glands with ducts that open into hair follicles

• Secrete sebum– Lubricates skin– Prevents drying

b. Sudoriferous (sweat) Glands• Coiled exocrine glands in dermis

& subcutaneous tissue• Eccrine – most numerous

– Ducts release sweat directly onto surface of the skin as a pore

– Cool the body• Apocrine – at armpits & groin

– Activate at puberty – Secrete in response to emotional

stress & sexual stimulation– Body odor results from bacteria

breaking down substances secreted from these glands

Sweat Glands

Sudoriferous Glands• Ceruminous

glands – secrete ear wax (cerumen)

• Ciliary glands – at edges of eyelids

• Mammary glands – in breast

c. Hair• Covers almost entire

body– Except palms, soles,

nipples, lips, some regions of external genitals

• Nonliving – composed mainly of keratin

• Developed from living cells in a bulb

• Melanocytes give hair its color

Hair Continued• Hair follicle – sheath

of connective & epithelial tissue that encloses hair

• Shaft – part of hair above the skin

• Arrector pili – involuntary smooth muscle that forms goose bumps; causes release of sebum when contracts

d. Nails

• Function– Protect fingers and toe– Help in grasping

objects• Made of keratin • Changes in nails can

be a result of disease processes

Nails• Structure

– Nail root – under skin, where new cells grow

– Nail plate – part of nail overlying skin

– Nail bed – epithelial tissue under nail plate

– Lanula – covers growing region of nail

– Cuticle – extension of stratum corneum, seals space between nail plate and nail root

• Skin does NOT breathe• Protection against infection• Protection against dehydration• Regulation of body temperature• Collection of sensory information• Other minor skin functions

– Limited absorption– Minimal excretion– Manufacture of Vitamin D

III. Skin Functions

Skin Functions

• Protection against infection– Stratum corneum is in a tight interlocking

pattern & constantly being shed• Protection against dehydration

– Keratin and sebum waterproof the skin and prevent water loss

Skin Functions

• Regulation of body temperature– Excess heat dissipated

• Large surface for heat to radiate into environment• Vessels dilate to allow heat loss• Sweat glands cause perspiration, which dissipates

heat when it evaporates from surface of skin– Protection from cold

• Vessels constrict to diminish heat loss– Most blood supply to skin is for temperature

regulation

Skin Functions• Skin is one of chief

sensory organs of body• Collection of sensory

information– Free nerve endings

• Pain• Temperature

– Sensory receptors• Light touch – Meissner

corpuscle• Deep pressure –

Pacinian corpuscle

Minor Skin Functions

• Limited absorption– Estrogens or steroids– Most skin medications are topical & local only

• Minor excretion– Electrolytes (salts) – Some nitrogen-containing wastes

• Vitamin D production– Needed for bone health– Manufactured in skin under UV radiation

a. Color

• Dependant on many factors– Amount of pigmentation– Blood flow to surface blood

vessels– Quality of blood flow to

surface vessels• Quantity of oxygen• Concentration of hemoglobin• Presence of compounds

such as bile

IV. Observation of the skin

Skin Pigmentation

• Melanin – main skin pigment– Also found in hair, iris of

the eye, middle coat of the eyeball

– Protects against UV radiation– Tanning – normal increase in

melanin• Albinism – hereditary lack of

pigment in skin, hair & eyes• Carotene – in orange & yellow

vegetables and stored in fatty tissue & skin

• Hemoglobin – seen in vessels near surface

Albinism

Discoloration of Skin• Pallor – is paleness of the skin. Paleness often due to loss of blood

supply or loss of hemoglobin– Most easily noted in lips, nail beds, mucous membranes

• Flushing – reddening of skin, often related to fever– Most noticeable in face and neck

• Cyanosis – bluish tone as a result of loss of oxygen – Symptom of heart failure breathing problems

• Jaundice – yellowish skin due to excessive bile pigments from liver, mainly bilirubin – Tumors, inflammation of liver (hepatitis), some blood diseases– Neonates with immature livers may not be able to process bilirubin

• Carotenemia – excessive intake of carrots leading to jaundice

Pallor Cyanosis

Cyanosis Jaundice

Jaundice Carotenemia

b. Skin Lesions

• Lesion – any wound or local damage to tissue

• Surface lesions –– Rashes - flat– Eruptions – raised– Erythema – redness of skin due to

inflammation• Deep lesions• Burns

Surface Skin Lesions• Macule – flat spot, neither raised or depressed

– measles – freckles

• Papule – firm raised bump – Pimple– Nodule – large papule

• Vesicle – raised area filled with fluid– Aka bulla– Chickenpox

• Pustule – raised area filled with pus– Infected vesicles

Stages of Chickenpox

Deep Skin Lesions• Excoriation – a scratch• Laceration – rough

jagged wound due to skin tearing

• Ulcer – due to disintegration death of tissue– Decubitis ulcer – bed

sore• Fissure – crack in skin

– Athlete’s foot

Burns to Skin• Caused by heat,

electricity, chemicals, abrasions

• Assessed in terms of depth and %age of body surface involved

• Replaces 1st, 2nd & 3rd degree burn classification

Classifying Skin Burns - DepthSuperficial partial-

thickness – epidermal involvement, may or may not be dermis involvement,• Reddened, may

blister• Like a sunburn

Classifying Skin Burns - DepthDeep partial-

thickness – epidermal and some dermal involvement • Blistered,

broken skin with weeping appearance

• Scalded appearance

Classifying Skin Burns - Depth• Full-thickness –

epidermis, entire dermis and possibly some hypodermis

• Broken, dry, pale skin

• Charring may be present

• May require grafting or loss of tissue

Classifying Burns to Skin – Body Surface Area

• Rule of nines– Body surface is

assigned percentage in multiples of nine

• Lund & Browder – more accurate, divides body into small areas

Burns

Complications of Burns• Infection• Respiratory

complications• Circulatory problems• Psychological impact• http://www.metacafe.c

om/watch/888126/drunk_driving_jacqueline_saburido/

Sunburn• Excessive exposure

to UV radiation• Acute - sunburn• Chronic

– Skin cancer – basal cell & squamous cell carcinoma, malignant melanoma

– Wrinkling, age spots and “leathering”

• Tanning no safer than sunlight

SPF Sun Protection Factor• A measure of UVB protection • Ranges from 1 to 45 or above. • An SPF of 15 will delay sunburn in a person who would otherwise

burn in 10 minutes to burn in 150 minutes. The SPF 15 sunscreen allows a person to stay out in the sun 15 times longer.

• There is currently no uniform measure of UVA absorption so SPF does not predict UVA protection

• The "protectiveness" of clothing can also be measured by SPF. The following are SPF's of various types of clothing: – Nylon Stockings - SPF 2 – Hats - SPF 3-6 – Summer-weight clothing - SPF 6.5 – Sun-protective clothing - up to SPF 30

• Begins after clotting & scabbing protects underlying tissue

• Healing occurs from the inside out in wounds

• Scar aka cicatrix – growth of connective tissue – strong but not flexible – Keloid – excessive

scar tissue

v. Skin Tissue Repair

Keloid

• Loss of fat & collagen• Thinning of dermis – “parchment skin”• Circulation declines – decreased ability to

tolerate cold• Decreased melanin production – grey hair• Decreased sebum secretion• Decreased eccrine & apocrine glands so

decreased ability to tolerate heat

VI. Aging & Integumentary System

A. Young Skin B. Old Skin

• Dermatitis• Psoriasis• Cancer• Acne & other skin infections• Alopecia• Allergies• Autoimmune disorders• Pressure ulcers

VII. Skin Disorders

Dermatitis

• Inflammation of skin due to an irritant• Atopic dermatitis – aka eczema – intense

itching and skin inflammation with erythema, vesicles, papules, scaling crusting – Generally begins in childhood and becomes

recurrent– Excessively sensitive skin – Often accompanied by other allergic disorders

Dermatitis

Psoraisis• Chronic overgrowth of

epidermis • Large outlined

erythematic plaques covered with silvery scales

• Chronic, recurrent with hereditary pattern

Psoraisis

Skin Cancer

• Most common form of cancer in USA• Epidermal skin cancers

• Basal cell and squamous cell carcinoma• Face, neck & hands• Squamous cell most likely to metastisize but both

are treatable• Melanoma – from moles (nevi) –

• irregular border & shape, uneven color, larger than pencil eraser size

• History of severe blistering sunburn is predisposing factor

Acne & Skin Infections• Acne vulgarus –

infection of sebaceous glands

• Impetigo – acute contagious staphylo-coccal infection; associated with lower socioeconomic status

Viral Skin Infections

• Herpes simplex virus – cold sores– Type I – around mouth– Type II - genital

• Shingles (herpes zoster) – same virus that causes chickenpox; follows nerve pathway and can last longer than a year; can be extremely painful

• Wart (verruca) – human papillomavirus– Genital warts associated with cervical cancer

Herpes Zoster

Fungal Skin Infections• Tinea (ringworm) corporis

– On foot – athlete’s foot– Can grow under acrylic nails– Difficult to treat

Alopecia• Baldness • Male pattern baldness• Can be due to

disease or drug therapy

• Alopecia areata –sudden loss of either patches of hair or all hair

Alopecia Areata Totalis

Allergy• Hypersensitivity to an

irritant that causes an unfavorable immune response

• Pruritus – itching• Urticaria – hives –

elevated patches also called wheals

Autoimmune Disorders• Immune reaction to one’s own tissues• Pemphigus – epidermal layer separates from dermis,

causing bullae (large blisters)• Fatal unless immune system suppressed

• Lupus erythematosus – chronic, inflammation of connective tissue

• Discoid lupus erythematosus – skin only• Systemic lupus erythematosus – involves skin & other

organs• Butterfly rash on cheeks• Worsened with sun exposure

• Scleroderma – overproduction of collagen causing thickening & tightening of skin

Pemphigus

Lupus

Scleroderma

Pressure Ulcers – Decubitis Ulcers

• Appear when body weight is on skin for prolonged time without moving

• Bony projections, heels,

• First appear as redness and can progress all the way to the bone

Decubitis Ulcer