Copyright 2007 by Mosby Inc an affiliate of

Called a membrane because it covers the body Called an organ because it contains several kinds of tissues Called a system because it has organs and other parts that work together for a particular function Copyright © 2007 by Mosby, Inc. , an affiliate of Elsevier Inc.

Epidermis—outermost layer Dermis—“true skin” Subcutaneous fascia or hypodermis— the innermost layer Copyright ©

Epidermis (cuticle) Outermost layer of the skin Composed of a surface of dead cells with an underlying layer of living cells Contains sebaceous and sudoriferous glands as well as hair follicles Melanocytes (produces melanin) are located in the epidermis Melanin: pigment that gives skin its color Copyright © 2007 by Mosby, Inc. , an affiliate of Elsevier Inc.

Dermis (corium) Called the “true” skin Contains the blood vessels and nerves Each inch of skin contains many blood vessels Subcutaneous Innermost layer Contains adipose, which cushions and insulates the body’s organs Copyright © 2007 by Mosby, Inc. , an affiliate of Elsevier Inc.

Skin has hair in all areas except the soles of the feet and palms of the hands Hair blocks 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 Hair- external insulation Copyright © 2007 by Mosby, Inc. , an affiliate of Elsevier Inc.

Three types of glands in the skin: Sebaceous glands (oil) Located everywhere except palms of hands and soles of feet Sebum (oil) causes the skin to be soft and waterproof Coat the hair with oil Sudoriferous glands (sweat) Help regulate the body temperature and excrete body wastes cool the body Copyright © 2007 by Mosby, Inc. , an affiliate of Elsevier Inc.

Ceruminous glands Located in the auditory canal of the ear Secrete wax that helps protect the ear from infection and prevents entry of foreign bodies Copyright © 2007 by Mosby, Inc. , an affiliate of Elsevier Inc.

Function is to protect fingers and toes from injury- protective covering Formed from dead, keratinized epidermal cells Root is covered by skin at the area of attachment to finger or toe Lunula is the crescent-shaped white area near the root Copyright © 2007 by Mosby, Inc. , an affiliate of Elsevier Inc.

Dermatology Study of skin Dermatitis is inflammation of the skin Skin lesions can be seen with visual inspection Size, shape, texture, and color often reveal cause Biopsy is used to identify the causative organism Fingerprints person and toe prints are unique to each Copyright © 2007 by Mosby, Inc. , an affiliate of Elsevier Inc.

Acne Caused by increased secretion of oil related to increased hormones during puberty Primarily affects the face, chest, and back Digests sebum Attracts neutrophils Neutrophil digestive enzymes cause lesions, “pus pockets” Oil-based cosmetics worsen disease Copyright © 2007 by Mosby, Inc. , an affiliate of Elsevier Inc.

Benzoyl peroxide dries plugged follicles, kills microbes Tetracycline (antibiotic) Accutane – inhibits sebum

Albinism Inherited produced disorder in which melanin is not Alopecia Baldness Athlete’s foot

Dandruff White flakes of dead skin cells from the scalp Eczema Group of disorders caused by allergic or irritant reactions Psoriasis Chronic skin disorder in which too many epidermal cells are produced Rashes May result from viral infection, especially in children Copyright © 2007 by Mosby, Inc. , an affiliate of Elsevier Inc.

Skin cancer Sun and skin cancer Damage by ultraviolet rays Types of skin cancer Three forms are basal, squamous, and melanoma Skin lesions Differ in texture, color, location, and rate of growth Copyright © 2007 by Mosby, Inc. , an affiliate of Elsevier Inc.

Skin and hair care Skin care products include soap, astringents, and cosmetics Ways to remove hair include wax, depilatory creams, and electrolysis Tattooing (permanent makeup) Risk of infections, allergic reaction, and complications during MRI Copyright © 2007 by Mosby, Inc. , an affiliate of Elsevier Inc.

House dust is mainly skin flakes! If you laid out all your skin on a flat surface, it would have an area of about 2 square meters. Skin weighs about 2. 5 kilograms - the largest organ in the body. What hurts if you pull it, but doesn't hurt if you cut it? Your hair, of course! Skin is elastic - it springs back into shape when stretched. Some medicines (estrogen, nicotine) can pass through the skin, but others cannot (insulin). Why is that? Because only fat-soluble substances can enter the skin, not water-soluble ones. Your hair stands on end and you develop 'goose bumps' because there are tiny muscles attached to the hair follicles and they contract when you are frightened or cold. Copyright © 2007 by Mosby, Inc. , an affiliate of Elsevier Inc.