5-1 Chapter 5 Integumentary System

5-2 Integumentary System

5-3 Integumentary System Consists of: –Skin –Hair –Nails –Glands Functions –Protection –Sensation –Temperature regulation –Vitamin D production –Excretion –Immunity

5-4 Skin. General Facts –One of the largest organs –Covers an area of 2m2 or 22ft2. –Thickness ranges from mm –Two General Divisions – Epidermis Dermis

5-5 Hypodermis Skin rests on this, but not a part Consists of loose connective tissue Types of cells –Fibroblasts –Adipose cells –Macrophages Also called –Subcutaneous tissue –Superficial fascia

5-6 Skin Dermis –Structural strength –Cleavage lines –Two layers Reticular Papillary Epidermis –Avascular –Cells –Layers or strata

5-7 Cleavage or Tension Lines Elastin and collagen fibers oriented in some directions more than others Important in surgery –If incision parallel to lines there is less gapping, faster healing, less scar tissue

5-8 Dermis and Epidermis

5-9 Epidermal Cells Cell types –Keratinocytes: Produce keratin for strength –Melanocytes: Contribute to skin color vitiligo = autoimmune loss of melanocytes in areas of the skin produces white patches –Langerhans’ cells: Part of the immune system –Merkel’s cells: Detect light touch and pressure Desquamate: Older cells slough off Keratinization: Cells die and produce outer layer that resists abrasion and forms permeability layer

5-10 Epidermal Strata Stratum Basale –Deepest portion of epidermis and single layer –High mitotic activity and cells become keratinized Stratum Spinosum –Limited cell division Stratum Granulosum –In superficial layers nucleus and other organelles degenerate and cell dies Stratum Lucidum –Thin, clear zone Stratum Corneum –Most superficial and consists of cornified cells

5-11 Epidermal Layers and Keratinization

5-12 Thick and Thin Skin Thick skin –Has all 5 epithelial strata –Found in areas subject to pressure or friction Palms of hands, fingertips, soles of feet Thin skin –More flexible than thick skin –Covers rest of body

5-13 Skin Color Determined by 3 factors –Pigments Melanin: Provides for protection against UV light Albinism: Deficiency or absence of pigment Carotene: Yellow pigment –Blood circulating through the skin Imparts reddish hue and increases during blushing, anger, inflammation Cyanosis: Blue color caused by decrease in blood oxygen content –Thickness of stratum corneum

5-14 Accessory Skin Structures Hair –Found everywhere on human body except palms, soles, lips, nipples, parts of external genitalia, and distal segments of fingers and toes Hair Color –Hair color is due primarily to the amount and type of melanin. –Graying of hair occurs because of a progressive decline in tyrosinase. –Dark hair contains true melanin –Blond and red hair contain melanin with iron and sulfur added –Graying hair is result of decline in melanin production –White hair has air bubbles in the medullary shaft Hormones influence the growth and loss of hair (Clinical applications).

5-15 Functions of Hair –Prevents heat loss –Decreases sunburn –Eyelashes help protect eyes –Touch receptors (hair root plexus) senses light touch Glands –Sebaceous (oil) glands –Sudoriferous (sweat) glands –Ceruminous (wax) glands –Mammary (milk) glands

5-16 Sebaceous (oil) glands –Sebaceous (oil) glands are usually connected to hair follicles; they are absent in the palms and soles –Secretory portion of gland is located in the dermis –produce sebum contains cholesterol, proteins, fats & salts moistens hairs waterproofs and softens the skin inhibits growth of bacteria & fungi (ringworm) –Acne bacterial inflammation of glands secretions are stimulated by hormones at puberty

5-17 Sudoriferous (sweat) glands –Eccrine sweat glands have an extensive distribution most areas of skin –secretory portion is in dermis with duct to surface –ducts terminate at pores at the surface of the epidermis. –regulate body temperature through evaporation (perspiration) –help eliminate wastes such as urea.

5-18 Apocrine sweat glands are limited in distribution to the skin of the axilla, pubis, and areolae; their duct open into hair follicles. –secretory portion in dermis –duct that opens onto hair follicle –secretions are more viscous Ceruminous Glands –Ceruminous glands are modified sudoriferous glands that produce a waxy substance called cerumen. found in the external auditory meatus contains secretions of oil and wax glands barrier for entrance of foreign bodies

5-19 An abnormal amount of cerumen in the external auditory meatus or canal can result in impaction and prevent sound waves from reaching the ear drum (Clinical Application).

5-20 Hair Structure Composed of shaft and root –Shaft protrudes above skin surface –Root located below surface and base forms the hair bulb Has 3 concentric layers –Medulla: Central axis –Cortex: Forms bulk of hair –Cuticle: Forms hair surface

5-21 Hair Growth, Color, and Muscles Hair Growth –Cycles Growth and resting –Permanent hair loss Pattern balding most common Hair Color –Caused by varying amounts and types of melanin Muscles –Arrector pili: Muscle contraction causes hair to “stand on end”

5-22 Oil and Sweat Glands Sebaceous glands –Produce sebum –Oils hair and skin surface Sudoriferous glands –Merocrine or eccrine Most common Numerous in palms and soles –Apocrine Found in axillae, genitalia, around anus

5-23 Nails Anatomy –Nail root proximally –Nail body distally: Eponychium or cuticle Growth –Grow continuously unlike hair

5-24 Burns Classifications –First-degree –Second-degree –Third-degree Skin Grafts –Split skin –Artificial skin –Cadavers or pigs

5-25 Burns –Destruction of proteins of the skin –chemicals, electricity, heat Problems that result –shock due to water, plasma and plasma protein loss –circulatory & kidney problems from loss of plasma –bacterial infection Two methods for determining the extent of a burn are the rule of nines and the Lund-Bowder method

5-26 The Rule of Nines

5-27 Aging Effects Skin more easily damaged Skin becomes drier Functioning melanocytes decrease or increase as with age spots Sunlight ages skin more rapidly

5-28 Clinical Disorders Bacterial infections –Acne Viral Infections –Chicken pox, German measles, cold sores Decubitus ulcers or bedsores –Ischemia and necrosis Cancer –Basal cell carcinoma –Squamous cell carcinoma –Malignant melanoma