Integumentary System and Body Membranes Structure and Function

2 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

3 Structure of the Skin: Layers EPIDERMIS DERMIS SUBCUTANEOUS TISSUE

4 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

5 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

6 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

7 SKIN STRUCTURE:

8 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

9 Appendages of the skin: Appendage..something that is attached Hair Receptors Nails Skin glands – Sweat – Sebaceous

10 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

11 HAIR:

12 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

13 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

14 NAILS:

15 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

16 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 17

18 Two Types of Membranes: Epithelial membranes – Cutaneous – Serous – Mucous Connective tissue membranes – Synovial

19 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

20 REVIEW BODY CAVITIES:

21 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

22 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

23 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

24 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. 25

Disorders of the Skin Skin Lesions Burns Skin Infections Skin Cancer

27 Disorders of the Skin Dermatosis..any disorder of the skin, skin condition Dermatitis.. involves inflammation of the skin

28 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

29 Burns Skin Damage or destruction caused by: Fire or contact with hot surfaces Overexposure to ultraviolet light (sunburn) Contact with electric current Harmful chemicals (acids)

Surface Area of Burns: The Rule of “9’s” 30

Burns: 31 Third degreesunburn

32 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

33 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: 34

35 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.

36 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: 37 Ringworm warts

38 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

39 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: 40

41 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

42 Skin Cancer Squamous cell carcinoma Basal cell carcinoma Melanoma Kaposi’s sarcoma

43 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

44 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

45 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

46 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