Integumentary System and Body Membranes

Structure and Function

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Love the Skin You’re In!

Skin..Cutaneous Membrane– Largest, most visible, primary

organ– Composes 16% of body weight– Superficial layer is epithelial,

underlying layer is connective

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Structure of the Skin: Layers

EPIDERMISDERMISSUBCUTANEOUS TISSUE

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Structure of the Skin:

Epidermis..outermost layer of the skin constantly replaced from underneath layer.

Dermis..deeper,thicker layer, composed of connective tissue

– Basis of fingerprints– Contain nerve endings, muscle fibers, hair follicles, sweat &

sebaceous glands, & blood vessels

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Structure of the Skin:

Subcutaneous tissue..thicker layer of loose connective tissue & fat – Insulates from heat & cold– Shock absorbing pad to protect– Stored source of food & energy

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Structure of the Skin:

Keratin..hard protein substance in nails, hair, skin,

Pigment ..produced by deepest layer of epidermis, gives color to the skin,

Melanin..Brown pigment produced by melanocytes in the epidermis

FYI: Millions of epithelial cells reproduced & shed daily

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SKIN STRUCTURE:

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FUNCTION OF SKIN:

Protection..first line of defense against– infection by microbes– ultraviolet rays from sun– harmful chemicals– cuts & tears

Temperature regulation– Regulation of sweat secretion– Regulation of blood flow close to the body surface

Sensory organ detects all changes in environment

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Appendages of the skin:

Appendage..something that is attached Hair Receptors Nails Skin glands

– Sweat– Sebaceous

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Appendages of the Skin:

Body Hair– Lanugo, extremely fine soft hair on newborn

infants– Follicles.. small tubes where hair growth

occurs– Hair root hidden in the follicle,visible hair

called shaft– Only hairless areas are lips, palms, and

soles

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HAIR:

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Appendages of the Skin:

Receptors– Make it possible for body surface to sense

touch,pain,temperature, & pressure– Meissner’s corpuscle ..close to the skin surface

make light touch sensation possible– Pacinian corpuscle.. deep in the dermis, detect

pressure on the skin surface– Free nerve endings ..respond to pain &

temperature changes – Krause’s end bulbs.. detect touch sensation & low

freq. vibrations

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Appendages of the Skin:

Nails– Nail body..visible part of the nail– Root..lies in a groove , hidden by a fold of skin– Cuticle..fold of skin which holds the nail body in

place– Lunula..crescent-shaped white area nearest the

root– Nail bed.. Under the nail, a layer of epithelium

containing abundant blood vessels

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NAILS:

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Appendages of the Skin:

Sudoriferous or Sweat Glands– Eccrine.. produce perspiration, (most numerous &

wide spread)– Apocrine sweat glands .. secretes thick, milky

secretions which breakdown & cause odor (found in axilla & around genitalia)

Sebaceous or Oil glands– Secrete oil or sebum for hair & skin– Secretion increases during adolescence– Sebum may darken in gland ducts to form

blackheads

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SWEAT GLAND:

What is a Membrane?

Simple thin, sheetlike cell structures – Cover & protect body surface– Lines body cavities– Cover inner surfaces of hollow organs– Secrete lubricating fluids

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Two Types of Membranes:

Epithelial membranes– Cutaneous– Serous– Mucous

Connective tissue membranes– Synovial

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Serous Membrane:

Found on the surface of closed cavities Composed of two distinct layers

– Parietal portion,lines the walls of body cavities

– Visceral portion,covers organs found in body cavities

Squamous epithelium & connective tissue called basement membrane

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REVIEW BODY CAVITIES:

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Examples of Serous Membranes:

Pleura: membrane of the thoracic cavity– Pleurisy : very painful inflammation of the pleura

that line the chest cavity & cover the lungs

Peritoneum: membrane in the abdominal cavity – Peritonitis : inflammation of the abdominal cavity

membranes, can be secondary to infected or ruptured appendix

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Mucous Membranes are:

Epithelial membranes that line body surfaces opening directly to the exterior of the body.

The mucocutaneous junction is where the skin & the mucous membranes meet.– Examples: eyelids, nasal openings, vulva ,and anus

have mucocutaneous junctions

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Connective Tissue Membranes:

Synovial membranes line the spaces between bones and joints

Secrete a thick, colorless lubricating fluid, synovial fluid, to reduce friction

Also line the bursae, small cushionlike sacs found between moving body parts.

FYI: Do not contain epithelial tissue

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The Skin in Perspective:

Architectural Marvel In one (1) inch of skin there are:

– 500 sweat glands– Over 1000 nerve endings– Nearly 100 sebaceous glands– 150 sensors for pressure– 75 sensors for heat– 10 sensors for cold– Millions of cells

FUN FACTS:

Humans shed and regrow outer skin cells about every 27 days.

Every square inch of skin has about 9.5 million skins cells

By age 70, the average person will have lost 105 pounds of skin.

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Disorders of the Skin

Skin Lesions

Burns

Skin Infections

Skin Cancer

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Disorders of the Skin

Dermatosis..any disorder of the skin, skin condition

Dermatitis..

involves inflammation

of the skin

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Skin Lesions

Lesion..any measurable variation from the normal structure of a tissue– Not necessarily signs of disease,Freckles are

lesions, but benign– May be elevated, flat,or depressed– Abnormal coloration, density,

calcification

Herpes Zoster lesion

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Burns

Skin Damage or destruction caused by:

Fire or contact with hot surfacesOverexposure to ultraviolet light

(sunburn)Contact with electric currentHarmful chemicals (acids)

Surface Area of Burns:

The Rule of “9’s”

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Burns:

31 Third degree sunburn

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Classification of Burns:

First-degree– Minimal tissue destruction– No blistering– Minor discomfort

Second-degree– Involves the deep epidermal layers– Damages sweat glands, hair follicles, sebaceous

glands– Blisters, severe pain, generalized swelling, fluid loss– Scarring is common, injures/destroys epidermal

layers

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Classification of Burns:

Third Degree – Full thickness burn– Complete destruction of epidermis & dermis– May extend into subcutaneous, muscle, and

bone– Serious fluid loss problem– Insensitive to pain immediately due to

destruction of nerve endings

Depth of Burns by degrees:

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Skin Infections Facts:

The skin is the first defense against Infection

Skin is commonly a site of infection

Conditions may be caused by viruses, bacteria, fungi or larger parasites.

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Skin Infections:

Impetigo..staph or strep infection in young children,starts with erythema, vesicles, then yellowish crusts

Tinea..fungal skin infections includes ringworm,

jock itch, and athlete’s foot. Signs include erythema,scaling and crusting, with itching.

Warts.. papilloma virus,benign neoplasm, contagious by direct contact. Removed by freezing, drying, laser therapy, chemical applications

Skin Infections:

37Ringworm warts

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Skin Infections:

Boils/Furuncles..staph infections of hair follicles. Large inflamed pustules.

Carbuncles.. group of untreated boils that fuse into larger pus-filled lesion.

Scabies.. Contagious condition

caused by itch mites. Young

mites hatch causing rash,

erythema

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Vascular/Inflammatory Skin Disorders:

Decubitus..pressure sores caused by lying in one position for long periods. Common sites include heels, and over bony prominences.

Urticaria..hives/itching,red raised lesions called wheals, caused by hypersensitivity or allergic reaction.

Scleroderma..autoimmune disease,mild localized inflammed patches which later turns yellowish, hardened skin.

Decubitus Ulcer:

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Vascular/Inflammatory Skin Disorders:

Psoriasis..common,

chronic inflammatory disorder of cutaneous tissue characterized by scaly plaques of epithelial tissue.

Eczema..most common inflammatory disorder, characterized by papules, vesicles, and crusts. It is a symptom of underlying condition. Example: Poison ivy causes contact dermatitis and eczema

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Skin Cancer

Squamous cell carcinomaBasal cell carcinomaMelanomaKaposi’s sarcoma

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Skin Cancer:

Squamous cell carcinoma– Malignant tumor of the epidermis– Most common type of skin cancer– Slow growing– Hard, raised nodules, usually painless– Will metastasize and invade other organs

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Skin Cancer:

Basal cell carcinoma– Occurs on upper face– Malignant, begins in base of

the epidermis– Begin as papule– Form bleeding, crusted

crater– Less likely to metastasize

than other types

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Skin Cancer:

Melanoma– Malignant,fastest growing,

serious cancer– Causes death in 1in 4 cases– May develop from pigmented

nevus (moles)– Use the “ABCD” rule to self

exam for melanoma

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Skin Cancer:

Kaposi’s Sarcoma– Rarer skin cancer– Appears in AIDS and

other immune deficiencies– Appears as purple

papules– Spreads quickly to lymph

nodes and internal organs

Skin Cancers:

47 USING THE “ABCD” RULE