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Integumentary System

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Integumentary System

• Composed of several tissues• Maintains homeostasis• Protective covering• Retards water loss• Regulates body temperature• Houses sensory receptors• Contains immune system cells• Synthesizes chemicals• Excretes small amounts of waste

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Skin Cells

• help produce Vitamin D needed for normal bone and tooth development

• some cells (keratinocytes) produce substances that simulate development of some white blood cells

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Layers of Skin

• Skin is one of the largest organs of the body • Epidermis• Dermis - “true skin”• Subcutaneous layer

• beneath dermis • not part of skin

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Epidermis• lacks blood vessels• keratinized

• thickest on palms and soles (0.8-1.4mm)• contains melanocytes which provide melanin• rests on basement membrane• made of stratified squamous• as cells are pushed from the deeper portion, they tend to die

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Dermis

• contains dermal papillae

• binds epidermis to underlying tissues• made of irregular dense connective tissue

• on average 1.0-2.0 mm thick

• contains muscle cells, nerve cell processes, specialized sensory receptors,

blood vessels, hair follicles, and glands

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Subcutaneous Layer

• Called “hypodermis”

• Made of loose connective tissue and adipose tissue

• insulates

• Contains major blood vessels

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Hair Follicles

• epidermal cells

• tube-like depression

• extends into dermis

• hair root

• hair shaft

• hair papilla• dead epidermal cells

• melanin• arrector pili muscle – when the muscle contracts, hair is pulled into an upright position (cold temp. or fright activates them)

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(nerve receptor)

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Nails

• protective coverings

• nail plate

• nail bed

• lunula – actively dividing region in the fingernail

• cuticle – fold of skin over the nail

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Sebaceous Glands

• usually associated with hair follicles

• holocrine glands

• secrete sebum – prevents the skin from drying out

• absent on palms and soles

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Sweat Glands

• sudoriferous glands – activated by heat, pain, fever and nervousness

• widespread in skin

• originates in deeper dermis or hypodermis

• eccrine glands – respond to elevated body temperature

• apocrine glands – respond to emotional stress and begin to function during puberty

•Causes body odor

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Regulation of Body Temperature

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Heat Production and Loss

•Radiation•Primary source of heat loss•Infrared heat rays escape from warmer surfaces to cooler surroundings.

•Conduction•Heat moves from the body into the molecules of cooler objects in contact with its surface•Ex. Sitting on a cold desk

•Evaporation•Sweat glands secrete sweat to the surface of the skin. As the sweat evaporates, it carries heat away from the surface cooling the skin.

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Problems in Temperature Regulation

Hyperthermia – abnormally high body temperature

Hypothermia – abnormally low body temperature

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Skin Color

Genetic Factors (greatest impact on skin color)

• varying amounts of melanin• varying size of melanin granules• albinos lack melanin

Environmental Factors• sunlight (melanocytes help to protect deeper cells from sunlight)• UV light from sunlamps• X-rays

• All of the above factors darkens melanin

Physiological Factors• dilation of dermal blood vessels• constriction of dermal blood vessels• accumulation of carotene

• jaundice - indicator of liver malfunction

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Healing of Cuts•Blood escapes from the dermal blood vessels. Platelets begin sticking together to form a clot. The blood clot and dried tissue fluid form a scab. Fibroblasts migrate to the injury site and produces new connective tissue.

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Healing of Burns

First degree burn – superficial partial-thickness

Second degree burn – deep partial-thickness

Third degree burn – full-thickness• autograft - using burn victims own skin that hasn’t

been damaged• homograft - using cadaver skin from a skin bank• various skin substitutes

•Amniotic membrane•Artificial membranes of silicone, polyurethane, or nylon

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Healing of Burns

•First degree•Superficial, skin red and dry•Involves only epidermis• Rx – cold water•Heals in one week (example: sunburn)

•Second degree•Epidermis and dermis•Pain, swelling, redness, and blistering•Subject to infection•Rx – pain medication, dry sterile dressing•Healing within two weeks

•Third degree•Epidermis, dermis, and subcutaneous layers (full thickness)•Loss of skin, blackened skin•May be life threatening•Rx – prevention of infection, fluid replacement, skin grafting

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Rule of Nines

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Burn Victim

• http://www.npr.org/programs/atc/features/2002/oct/texas_dwi/index.html

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Don’t forget about Stems Test 2 Tomorrow and your Skin

Quiz Friday!

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Common Skin Disorders

• Acne– Disorder of sebaceous glands– Sebum plugs pores and area fills with leukocytes (white blood

cell)– Also, blackheads, cysts, pimples and scarring

• Albinism – absence of melanin• Alopecia – baldness• Athlete’s foot

– Contagious fungal infection– Usually contracted in public baths and showers– Rx – antifungal agents

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Common Skin Disorders

Acne

Alopecia

Albinism

Athlete’s Foot

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Common Skin Disorders

• Boils (carbuncles)– Painful, bacterial infection of hair follicle or sebaceous glands– Rx – antibiotics, excision and drainage of affected area

• Dermatitis– Non-specific skin inflammation– Rash – reaction to soap, plants, etc.– Skin blotches – caused by stress

• Eczema– Acute or chronic inflammatory skin disease– Skin dry, red, itchy and scaly– Rx – remove cause, hydrocortisone to help alleviate symptoms

• Excoriation - abrasion

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Common Skin Disorders

Boil

Dermatitis

Eczema

Excoriation

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Common Skin Disorders

• Herpes– Herpes simplex I

• Viral• Fever blister or cold sore

– Shingles (herpes zoster)• Viral infections of nerve endings• On chest or abdomen, accompanied by severe pain

• Impetigo– Acute, inflammatory and contagious– Seen in babies and young children– Caused by staphylococcus or streptococcus– Vesicles that rupture and develop distinct yellow crusts

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Common Skin Disorders

Herpes Simplex I Shingles

Impetigo

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Common Skin Disorders

• Pruritis - itching• Psoriasis

– Chronic inflammatory skin disease– Dry reddish patches covered with silvery-white scales

• Ringworm– Contagious fungal infection– Raised, itchy circular patches with crusts

• Scabies– Communicable – transmit from one person to another– Severe itching– Mite burrows in skin, lays eggs, eggs hatch

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Common Skin Disorders

Scabies

Ringworm

Pruritis

Psoriasis

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Common Skin Disorders

• Skin cancer– Associated with exposure to sun (UV rays)– Most common type of cancer in people– Skin cancer cells are most likely to occur from nonpigmented epithelial

cells• Basal cell carcinoma (Cutaneous carcinoma)

– Occurs mostly in middle-aged people who have a light complexion and work or plays outdoors

– Most common, least malignant– Usually on face– Rx – surgical removal or radiation

• Squamous cell carcinoma– Mostly scalp and lower lip– Grows rapidly, metastasizes to lymph nodes– Rx – surgical removal or radiation– Prognosis good with early diagnosis

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Common Skin Disorders

Basal Cell Carcinoma

Squamous Cell Carcinoma

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Common Skin Disorders

• Melanoma– Malignant– Occurs in melanocytes– Metastasizes to other areas quickly– Brown or black irregular patch that occurs

suddenly– Change in existing wart or mole may indicate

melanoma– Rx – surgical removal of melanoma and

surrounding area and chemotherapy

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Common Skin Disorders

Melanoma

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Common Skin Disorders

• Skin lesions– Pustule – small collection of pus in the top layer of skin – Tumor– Ulcer (superficial and decubitus – lying down)– Vesicle

• Urticaria (hives)– Itchy wheals or welts– Usually allergic reaction to drugs, food, etc.– Rx – avoid allergen

• Warts (verrucae)– Caused by virus– Some disappear spontaneously, others removed with

liquid nitrogen, chemicals, or laser

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Common Skin Disorders

Urticaria

Warts

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Life Span Changes

• Skin becomes scaly• Age spots appear• Epidermis thins• Dermis becomes reduced• Loss of fat• Wrinkling• Sagging• Sebaceous glands secrete less oil

• Melanin production slows• Hair thins• Number of hair follicles decrease• Nail growth becomes impaired• Sensory receptors decline• Body temperature unable to be controlled• Diminished ability to activate Vitamin D

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Clinical Application

Acne Vulgaris

•most common skin disorder•sebum and epithelial cells clog glands•produces whiteheads and blackheads (comedones)•anaerobic bacteria trigger inflammation (pimple)•largely hormonally induced•Androgens (hormone) stimulate sebum production•treatments include antibiotics, topical creams, birth control pills