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 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

Copyright 2003 by Mosby, Inc. All rights reserved. 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 Copyright 2003 by Mosby, Inc. All rights reserved.

Copyright 2003 by Mosby, Inc. All 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 Copyright 2003 by Mosby, Inc. All rights reserved.

Layers of Skin Subcutaneous- hypodermis 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

Copyright 2003 by Mosby, Inc. All rights reserved. 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 Copyright 2003 by Mosby, Inc. All rights reserved.

Copyright 2003 by Mosby, Inc. All 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 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 Copyright 2003 by Mosby, Inc. All rights reserved.

Abnormal color/homeostatic imbalances Pallor (blanching) Emotional distress, anemia, low BP Erythema (redness) 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)

Copyright 2003 by Mosby, Inc. All rights reserved. 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) Copyright 2003 by Mosby, Inc. All 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: Arrection Pili= hair muscles 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

Copyright 2003 by Mosby, Inc. All rights reserved. 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 Copyright 2003 by Mosby, Inc. All 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 Copyright 2003 by Mosby, Inc. All rights reserved.

Sebaceous glands

Sudoriferous (sweat) glands Apocrine (sweat) glands- secrete at hair follicle and active at puberty 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

Copyright 2003 by Mosby, Inc. All rights reserved. Sudorfierous glands Copyright 2003 by Mosby, Inc. All 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