INTEGUMENTARY SYSTEM CLASSIFICATION OF BODY MEMBRANES

• Epithelial membranes • Cutaneous membranes • Mucous membranes • Serous membranes • membranes • Synovial membranes SEROUS MEMBRANES

• Functions • Secretes serous (watery) fluids • Lubricates surfaces of membranes • Locations • Lines body cavities with no outside openings • Parietal pleura, parietal peritoneum • Covers organs • Visceral pleura, peritoneum SEROUS MEMBRANES • Examples of specific serous membranes • Peritoneum • Abdominal cavity • Pleura • Around the • Pericardium • Around the heart MUCOUS MEMBRANES

• Function • Secretes mucus • Locations • Lines cavities, tubes with outside openings • Examples: oral and nasal cavities • Digestive, urinary, respiratory, reproductive systems CONNECTIVE TISSUE MEMBRANE • Synovial membrane • Functions • Secretes synovial fluid • Lubricates ends of bones • Locations • Inner linings of cavities of bones of freely movable CUTANEOUS MEMBRANE

• Functions • Example: • Protection • Dry membrane • Temperature regulation • Outermost protective • Excretion of water and boundary salts • Sense organs • Locations • • • Subcutaneous layers

• Skin (cutaneous membrane) • Skin appendages (derivatives) • Sweat glands • Oil glands • • Nails SKIN FUNCTIONS

• Reduces water loss • Regulates body temperature • Excretes waste • Prevents harmful substances and microorganisms from entering the body • Synthesizes vitamin D • Protection form UV radiation • Sensory receptors in skin monitor external environment SKIN STRUCTURE

• Epidermis—outer layer • Stratified squamous epithelium • Dermis • Dense connective tissue • (hypodermis) is deep to dermis • Not part of the skin • Anchors skin to underlying organs • Composed mostly of EPIDERMIS

• Epidermis—outer layer • Stratified squamous epithelium • Often keratinized (hardened by keratin) • Thin skin: 1-3 mm • Thick skin: 4-5 mm • Soles of feet • Palms of hands • Functions • Shields underlying tissues from excess water loss • Protects from mechanical injury • Prevents entrance of pathogens • Protects deeper cells from sunlight damage CELLS OF THE EPIDERMIS

• • Filled with tough fibrous keratin • 90% of epidermis • Principal structural element of outer skin • • Contribute color to skin • Filter UV light • Defense mechanism LAYERS OF THE EPIDERMIS

• • Horny layer • Outermost layer of epidermis • Shingle-like dead cells are filled with keratin • Cell membranes are thick and chemically resistant • Desmosomes hold adjacent keratinocytes together • Barrier to water loss, microorganisms, harmful chemicals, physical trauma LAYERS OF THE EPIDERMIS

• • Clear layer • Keratinocytes are clear and closely packed together • Occurs only in thick, hairless skin of the palms of hands and soles of feet LAYERS OF THE EPIDERMIS

• • Granular layer • Keratinization begins • Cells degenerating • May be missing in some thin skin LAYERS OF THE EPIDERMIS

• Stratum germinativum • growth layer • Made of s. spinosum and s. basale LAYERS OF THE EPIDERMIS

• • Spiny layer • Prominent desmosomes • Gives cells “prickly” look. • Rich in RNA to initiate protein synthesis LAYERS OF THE EPIDERMIS

• • Base layer • Deepest layer of epidermis • Lies next to dermis • Cells undergoing mitosis LAYERS OF THE EPIDERMIS

• Summary of layers from deepest to most superficial • Stratum basale • Stratum spinosum • Stratum granulosum • Stratum lucidum (thick, hairless skin only) • Stratum corneum LAYERS OF THE EPIDERMIS EPIDERMIS

• Regeneration time • Approximately 35 days • Accelerated abrasion triggers increased mitotic activity, shortened turnover, and a callus develops EPIDERMIS: BLISTERS

• Basic reaction of skin injury • Desmosomes are weakened or destroyed by physical or chemical stress • Skin falls away from body and fills with fluid • Results from burns, friction injuries, exposure to primary irritants, accumulation of toxic products following cell death in skin DERMIS • Thick layer with and fibers that give skin strength and flexibility • 0.5 mm in to 4 mm thick in the soles and palms • Function • Protection against mechanical injury • Provides padding • Storage area for water and electrolytes • Network of and endings provide sensory information • Muscle fibers, hair follicles, sweat, sebaceous glands, and blood vessels located here • Two layers: • Papillary • Reticular DERMIS: PAPILLARY LAYER • Upper dermal region • Thinner layer • Projections called dermal papillae • Project into epidermis • Epidermis clings tightly , forming ridges • important to survival • Allows us to grip surfaces to walk and grasp tools DERMIS: RETICULAR LAYER • Deepest skin layer • Thicker layer • Tough, interlacing white collagenous fibers • Elastic fibers allow stretching • Contains in face and scalp, allowing for facial movements • Arrector pili muscles (smooth muscle) attached hair follicles • Blood vessels • Sweat and oil glands • Deep pressure receptors DERMIS: RETICULAR LAYER

• Regeneration • Does not regenerate much • To heal wounds, reproduce and form an unusually dense mass of new connective tissue • Results in scar if not replaced by normal tissue STRETCH MARKS

• Elastic fibers stretched too much, weaken, and tear. • Forms pinkish or bluish depressed furrows • When healed, striae (furrows) appear as silver/ white scar lines TEMPORARY COLOR CHANGES OF SKIN

• Vasoconstriction • When skin blood vessels constrict, blood volume is reduced and skin becomes paler. • Vasodilation • When blood vessels dilate, skin becomes pinker • Cyanosis • Excess amount of unoxygenated hemoglobin in blood of skin capillaries SUBCUTANEOUS LAYER

• Layer of tissue below the dermis attaching the skin to the underlying muscle or bone • Rich in and areolar tissue • Density and arrangement of fat cells and collagen fibers determine the relative mobility of skin SKIN STRUCTURE NORMAL SKIN COLOR DETERMINANTS • Melanin • Yellow, brown, or black pigments • Carotene • Orange-yellow pigment from some vegetables • Hemoglobin • Red coloring from blood cells in dermal capillaries • Oxygen content determines the extent of red coloring MELANIN

• Pigment (melanin) produced by melanocytes • Number of melanocytes produces is about the same among all races • Melanocytes are mostly in the stratum basale • Amount of melanin produced depends upon genetics and exposure to sunlight • Accounts for most color variations SKIN COLOR

• Amount of melanin produced accounts for most skin color variations • Amino acid tyrosine is converted to melanin • Pigment granules are transferred to other epidermal cells • Process regulated by tyrosine (responsible for bruises in fruit) FACTORS AFFECTING SKIN COLOR

• Heredity (4-6 genes) • Sunlight • Prolonged exposure causes increased production • Hormone secretion • Adrenocorticotropic hormone (ACTH) • stimulating hormone (MSH) • Increasing age • Decrease in tyrosine activity • Results in gray hair SKIN APPENDAGES

• Hair • Hair follicles • Nails • Cutaneous glands are all exocrine glands • Sebaceous glands • Sweat glands APPENDAGES OF THE SKIN: HAIR

• Location • Found everywhere except palms, soles, , , areas of genitalia • Functions • Protection • Regulation of body temperature • Produced by • Small tube formed by epidermal cells that spread down into dermis APPENDAGES OF THE SKIN: HAIR

• Consists of hard keratinized epithelial cells • Germinal matrix: Responsible for forming . Cells become keratinized as they push upward following mitosis. • Hair papilla • Small mound of dermis protruding into matrix containing capillaries to nourish matrix • Melanocytes provide pigment for hair color APPENDAGES OF THE SKIN: HAIR • Hair • Root: hidden in follicle • Shaft: visible part of hair • Central : inner core. • surrounds medulla. Layers of keratinized cells. Amount of melanin deposited here determines color, adds strength. • on outside of cortex • Most heavily keratinized APPENDAGES OF THE SKIN: HAIR • Associated hair structures • Hair follicle • Dermal and epidermal sheath surround hair root • • Smooth muscle • Pulls hairs upright when cold or frightened • • APPENDAGES OF THE SKIN: HAIR APPENDAGES OF THE SKIN: NAILS

• Scale-like modifications of the epidermis • Heavily keratinized • Stratum basale extends beneath the bed APPENDAGES OF THE SKIN: NAILS

• Nail structures • Free edge • Nail body is the visible attached portion • Root of nail embedded in skin; hidden by cuticle • : crescent shaped white area • Nail bed: layer of epithelium under nail. APPENDAGES OF THE SKIN: SWEAT GLANDS • Fluid rich in salts, ammonia, uric acid, urea, other wastes • Widely distributed in skin • Two types • Eccrine glands • Apocrine glands APPENDAGES OF THE SKIN: SWEAT GLANDS

• Eccrine sweat glands • Structure: simple, coiled, tubular gland • Location: most numerous • Distributed all over body surface except lips, ear canal, glans penis, and nail beds • Function • Help maintain constant core temperature by producing sweat APPENDAGES OF THE SKIN: SWEAT GLANDS

Apocrine sweat glands Structure: simple, branched tubular glands connected with hair follicles Location: deep in subcutaneous layer of axilla, areola of , pigmented skin around anus Function Enlarge and begin to function at puberty. Produce more viscous and colored secretion. Odor due to contamination and decomposition of secretion by skin bacteria. SWEAT AND ITS FUNCTION

• Composition • Mostly water • Salts and vitamin C • Some metabolic waste • Fatty acids and proteins (apocrine only) • Function • Helps dissipate excess heat • Excretes waste products • Acidic nature inhibits bacteria growth • Odor is from associated bacteria APPENDAGES OF THE SKIN: SEBACEOUS GLANDS

• Structure: simple branched glands • Location: Most have ducts that empty into hair follicles; others open directly onto skin surface APPENDAGES OF THE SKIN: SEBACEOUS GLANDS

• Function: produce sebum (oil) • Lubricant for skin • Prevents brittle hair • Kills bacteria; lipids reduce fungal activity • Protect against water loss • Glands are activated at puberty • Sebum may accumulate in and enlarge ducts of sebaceous glands, causing whiteheads • If oil oxidizes, they become blackheads APPENDAGES OF THE SKIN: CERUMINOUS GLANDS

• Structure: modified apocrine sweat glands; simple coiled ducts. • Mixed secretions produce cerumen: brown, waxy substance • Location: open onto free surface of hair follicles in ear • Function • Protects skin from dehydration • Can harden and block the ear canal, causing hearing loss HOMEOSTASIS OF BODY TEMPERATURE

• Allows biochemical reactions to occur • Heat production results from metabolism of food • Heat loss • Vasodilation of dermal vessels. • 80% of heat is transferred through the skin; 20% is transferred through the mucous membranes HOMEOSTASIS OF BODY TEMPERATURE

• Transfer of Heat • Conduction • Evaporation • Transfer of heat to substance in contact • Radiation with body • Transfer of heat from • Ex: clothing, jewelry one surface to another without contact • Convection • Ex: heating system • Transfer of heat by movement of heated air or particles • Ex: step from pool to in front of fan HOMEOSTASIS OF BODY TEMPERATURE

• Negative feedback loops • Temperature receptors detect changes in body’s internal temperature • Disturbance increases body temperature above set point • Hypothalamus sends signal to sweat glands and blood vessels. • Sweat glands increase output; vessels dilate until set point reached again SKIN HOMEOSTATIC IMBALANCES

• Infections • Athlete’s foot (tinea pedis) • Caused by fungal infection • Boils and carbuncles • Caused by bacterial infection • Cold sores • Caused by virus SKIN HOMEOSTATIC IMBALANCES

• Infections and allergies • Contact dermatitis • Exposures cause allergic reaction • Impetigo • Caused by bacterial infection • Psoriasis • Cause is unknown • Triggered by trauma, infection, stress SKIN HOMEOSTATIC IMBALANCES

Figure 4.10 SKIN HOMEOSTATIC IMBALANCES

• Burns • Tissue damage and cell death caused by heat, electricity, UV radiation, or chemicals • Associated dangers • Dehydration • Electrolyte imbalance • Circulatory shock RULE OF NINES

• Way to determine the extent of burns • Body is divided into 11 areas for quick estimation • Each area represents about 9% of total body surface area SEVERITY OF BURNS

• First-degree burns • Partial thickness: Only epidermis is damaged • Skin is red and swollen; minor discomfort; some peeling. • No blisters SEVERITY OF BURNS

• Second-degree burns • Epidermis and upper dermis are damaged • Injury to upper layers of dermis damage possible to glands and hair follicles • Skin is red with blisters; severe pain; swelling; ; scarring SEVERITY OF BURNS

• Third-degree burns • Destroys entire skin layer; may involve underlying muscles and bone • Burn is gray-white or black • Insensitive to pain due to damage to nerve endings • Scarring a serious problem SEVERITY OF BURNS CRITICAL BURNS

• Burns are considered critical if • Over 25% of body has second-degree burns • Over 10% of the body has third-degree burns • There are third-degree burns of the face, hands, or feet SKIN CANCER

• Cancer—abnormal cell mass • Classified two ways • Benign • Does not spread (encapsulated) • Malignant • Metastasized (moves) to other parts of the body • Skin cancer is the most common type of cancer SKIN CANCER TYPES

• Basal cell carcinoma • Least malignant • Most common type • Arises from stratum basale SKIN CANCER TYPES

• Squamous cell carcinoma • Metastasizes to lymph nodes if not removed • Early removal allows a good chance of cure • Believed to be sun- induced • Arises from stratum spinosum SKIN CANCER TYPES

• Malignant melanoma • Most deadly of skin cancers • Cancer of melanocytes • Metastasizes rapidly to lymph and blood vessels • Detection uses ABCD rule ABCD RULE

• A = Asymmetry • Two sides of pigmented mole do not match • B = Border irregularity • Borders of mole are not smooth • C = Color • Different colors in pigmented area • D = Diameter • Spot is larger than 6 mm in diameter