Chapter 6 Integumentary System Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

Introduction Two or more kinds of tissues grouped together and performing specialized functions constitutes an organ. The skin and its various structures make up the integumentary system. The skin is the largest organ in the body.

Skin and Its Tissues Many functions: 1) Protective covering – prevents many harmful substances from entering 2) Retards water loss 3) Regulates body temperature 4) Sensory organ (sense of touch) 5) Contains immune system cells 6) Synthesizes chemicals (ex: Vitamin D) 7) Excretes small amounts of waste

© The McGraw-Hill Companies, Inc./Al Telser, photographer Layers of Skin The skin is composed of two layers: 1) Epidermis 2) Dermis Subcutaneous layer (hypodermis) - Beneath dermis Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Stratified squamous epithelium Dense irregular connective tissue Adipose tissue © The McGraw-Hill Companies, Inc./Al Telser, photographer

Epidermis Made of stratified squamous epithelium Lacks blood vessels Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Made of stratified squamous epithelium (a) Hair shaft Epidermis Hair follicle (b) Sebaceous gland Dermis Sweat Sweat gland pore Capillary Stratum corneum Stratum basale Dermal papilla Arrector pili muscle Lamellated (Pacinian) corpuscle Basement membrane Sweat gland Nerve cell process Adipose tissue Blood vessels Muscle layer Sweat gland duct Subcutaneous layer T Tactile (Meissner’s) corpuscle Lacks blood vessels Keratinized Melanocytes produce melanin (Melanosomes – pg. 174) Rests on basement membrane Thickest on palms and soles (0.8-1.4mm) Other areas – thin: (0.07-0.12 mm thick) b: © Victor Eroschenko

b: © The McGraw-Hill Companies, Inc./Al Telser, photographer Epidermis There are five (5) layers of the epidermis: Stratum corneum – outermost layer “horn-like” Stratum lucidum (only in thick skin – palms, soles) Stratum granulosum Stratum spinosum Stratum basale – deepest layer; melanocytes here Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Stratum corneum Stratum lucidum Stratum granulosum Stratum spinosum Stratum basale Basement membrane Dermal papilla Dermis (a) (b) b: © The McGraw-Hill Companies, Inc./Al Telser, photographer

Come, Let’s Get Sun Burned

Epidermis Heredity and environment determine skin color 1) Genetic Factors: All people have about the same number of melanocytes. Differences in color are due to differences in the amount of melanin produced, which is controlled by genes. Albinism – genetic disease that affects many species. Melanin is not produced, so the skin and hair are very pale, and the eyes appear pale blue to red. 2) Environmental Factors also influence the amount of melanin: UV rays from the sun (and sunlamps) and X-rays stimulate melanocytes to produce more melanin and also cause darkening of the melanin

Figure 06.03b Pigment recipient cells (pg. 174)

Epidermis Physiological Factors that also affect skin color: Cyanosis – bluish tint to skin due to low blood oxygen concentration Jaundice – yellowish skin tone due to liver disease (“bili lights” – pg. 177) Blushing - Dilation of dermal blood vessels Paleness - Constriction of dermal blood vessels due to low body temperature or being frightened, or anemia (low red blood cell count) Carotene, a yellow-orange pigment in certain vegetables, can give skin a yellowish color if a person consumes too much

Dermis made of Dense irregular connective tissue Dermal papillae – nipple-like conical projections of dermis into the epidermis. Increase surface area for epidermal cells to receive nutrients and oxygen by diffusion Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Hair shaft Sweat gland pore Sweat Stratum corneum Epidermis Stratum basale Capillary Dermal papilla Basement membrane T actile (Meissner’s) corpuscle Dermis Contains: Muscle cells, (arrector pili muscle), Hair follicles, blood vessels, Sebaceous glands, sweat glands, Sensory and motor nerve endings Sebaceous gland Arrector pili muscle Sweat gland duct Lamellated (Pacinian) corpuscle Hair follicle Subcutaneous layer Sweat gland Nerve cell process Adipose tissue Blood vessels Muscle layer (a) On average 1.0-2.0mm thick

Dermis Fingerprints are undulations (ridges) in the skin. The pattern is genetically determined, but is also influenced by early fetal movements in the womb. This is why even indentical twins have unique fingerprints.

Subcutaneous Layer Also known as the hypodermis Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Loose connective tissue and Adipose tissue Hair shaft Sweat gland pore Sweat Stratum corneum Epidermis Stratum basale Capillary Dermal papilla Basement membrane T actile (Meissner’s) corpuscle Dermis Insulates, cushions Sebaceous gland Arrector pili muscle Sweat gland duct Lamellated (Pacinian) corpuscle Hair follicle Many blood vessels present Subcutaneous layer Sweat gland Nerve cell process Adipose tissue Blood vessels Muscle layer (a)

6.3: Accessory Structures of the Skin Accessory structures of the skin originate from the epidermis and include: Hair follicles Nails Skin glands

Hair Follicles Arrector pili muscle – Follicle is made from Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Follicle is made from epidermal cells that form a tube-like depression into the dermis. How a hair is formed: specialized epidermal cells at base of hair follicle divide and push older cells upward. These become keratinized and die, forming the hair shaft. (hair papilla – pg. 178) Hair shaft Pore Sebaceous gland Arrector pili muscle Hair root (keratinized cells) Hair follicle Eccrine sweat gland Region of cell division Arrector pili muscle – contracts and forms “goose bumps” Hair papilla Dermal blood vessels (a)

Nails Protective covering of digits Three parts: Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Protective covering of digits Three parts: 1) Nail plate = the nail 2) Nail bed – underlying tissue to which the nail is attached 3) Lunula - whitish half- moon shaped region at base of nail. Specialized epidermal cells give rise to keratinized cells that form the nail plate, pushing it forward over the nail bed. Lunula Nail bed Nail plate

Sebaceous Glands Holocrine glands Usually associated with hair follicles Secrete sebum (oil) – softens and waterproofs hair and skin Acne – disorder of sebaceous glands. Whiteheads and black- heads caused by excess sebum and squamous epithelial cells clogging the gland. © Per H. Kjeldsen

Sweat Glands Two types of glands that produce sweat: Eccrine – respond throughout life to increased body temperature. Ducts open at the surface of skin as a pore. Apocrine – become active at puberty. Responsible for causing body odor (when bacteria metabolize the secretion). Also produce moist- ure when a person is upset, frightened or in pain, and during sexual arousal. Ducts open into hair follicles. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Hair shaft Pore Dermal papilla Sebaceous gland Duct Hair follicle Eccrine sweat gland Apocrine sweat gland

Sweat Glands Sweat is mostly water, but also contains small amounts of salts and wastes, such as urea and uric acid. Thus, sweating is also an excretory function. Other glands classified as specialized sweat glands (do not produce sweat): Ceruminous glands – located in external ear canal. Produce cerumen = ear wax. Mammary glands – in the breast. Produce milk.

Regulation of Body Temperature Regulation of body temperature is vitally important because even slight shifts can disrupt the rates metabolic reactions. *Study this diagram in your text and know it.

Heat Production and Loss Heat is a product of cellular metabolism The most active body cells are the heat producers and include: Skeletal muscle Cardiac muscle Cells of certain glands such as the liver The primary means of heat loss is radiation Also there is conduction, convection and evaporation (definition of these terms – pg. 182 new text) Hyperthermia – abnormally high body temperature Hypothermia – abnormally low body temperature

Healing of Wounds and Burns Inflammation is a normal response to injury or stress. Blood vessels in affected tissues dilate and become more permeable, allowing fluids to leak into the damaged tissues. (This can aid healing by providing more nutrients and oxygen.) Inflamed skin will become: Reddened Swollen Warm Painful

Healing of a Cut Healing of a Cut If injury extends into the dermis (or subcutaneous) layer: Blood vessels break – Blood clot forms  fluids seep into area and dries - Scab forms  epithelial cells grow beneath scab - bridging gap  fibroblasts migrate to area - secrete collagen fibers that bind edges of wound; C.T. matrix releases growth factors that stimulate cells to divide and replace tissue  blood vessels invade; phagocytic cells remove dead tissue  scab sloughs off Granulation - small, rounded mass consisting of a new blood vessel + fibroblasts secreting collagen. These Form in large, open wounds that eventually produce a scar composed primarily of collagen.

Steps of Wound Healing (pg. 185) Scab

Burns & Healing First degree burn – Epidermis only (superficial, partial-thickness). Heals within days-2 weeks, with no scarring. Second degree burn – Epidermis and partial dermis (deep, partial-thickness). Blisters appear. Healing – stem cells associated with accessory structures deep in the dermis (glands, hair follicles) – New epidermis is formed. Can completely heal with no scarring. Third degree burn – Epidermis, full dermis, and accessory structures (deep, full-thickness). Dry & leathery. Healing – Growth of epithlium inward from margin of burn. Loss of function. May require a skin transplant: Allograft – person to person (cadaveric skin) Autograft (Homograft) – patient’s own tissue Various skin substitutes

“Rule of Nines” Formula used by physicians to estimate the extent of body surface area affected in a burn patient. Skin’s surface area is divided into regions that equal 9% (or some multiple of 9%) of total surface area. Estimate is important for planning: Body fluid and electrolyte replacement Covering the area with skin or skin substitutes

“Rule of Nines” for Adults Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Anterior head and neck 41/2% 41/2% Anterior and posterior head and neck 9% 41/2% Posterior head and neck 41/2% Anterior trunk 18% Anterior and posterior upper extremities 18% Posterior trunk 18% Anterior upper extremities 9% Anterior and posterior trunk 36% Posterior upper extremities 9% 41/2% 41/2% 41/2% 41/2% Perineum 1% 9% 9% 9% 9% Anterior lower extremities 18% Anterior and posterior lower extremities 36% Posterior lower extremities 18% 100%

6.6: Lifespan Changes Skin becomes scaly Age spots appear Epidermis thins Dermis becomes reduced Loss of fat (chill easier) Wrinkling Sagging Sebaceous glands secrete less oil Melanin production slows Hair thins Number of hair follicles decreases Nail growth becomes impaired Sensory receptors decline Body temperature unable to be controlled as well Diminished ability to activate Vitamin D

Important Points in Chapter 6: Outcomes to be Assessed 6.1: Introduction Define organ, and name the large organ of the integumentary system. 6.2: Skin and Its Tissues List the general functions of the skin. Describe the structure of the layers of skin. Summarize the factors that determine skin color. 6.3: Accessory Structures of the Skin Describe the accessory structures associated with the skin. Explain the functions of each accessory structure of the skin.

Important Points in Chapter 6: Outcomes to be Assessed 6.4: Regulation of Body Temperature Explain how the skin helps regulate body temperature. 6.5: Healing of Wounds and Burns Describe the events that are part of wound healing. Distinguish among the types of burns, including a description of healing with each type. 6.6: Lifespan Changes Summarize lifespan changes in the integumentary system.

Read 1) Transdermal patches – pg. 113 (old text) 2) Decubital ulcers (bed sores) – pg. 116 3) Skin cancer – pg. 119

Burn Treatment A 32 year old man was attempting to get rid of some weeds in an overgrown garden by dousing them with gasoline and burning them. The can of gasoline ignited and exploded, and he sustained 3rd degree burns on both arms, his chest, back and head. Calculate the following (Body wt = 180 lbs.): 1) Percent body surface area burned (TBSA), using the “Rule of Nines.” 2) Fluid replacement therapy for the first 24 hours, using the Parkland formula: Lactated Ringers 4 mls x kg. body wt. x %TBSA (Round weight to the nearest whole kg) Half of the amount infused within the first 8 hours post-injury The remainder infused over the next 16 hours

“Rule of Nines” for Adults Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Anterior head and neck 41/2% 41/2% Anterior and posterior head and neck 9% 41/2% Posterior head and neck 41/2% Anterior trunk 18% Anterior and posterior upper extremities 18% Posterior trunk 18% Anterior upper extremities 9% Anterior and posterior trunk 36% Posterior upper extremities 9% 41/2% 41/2% 41/2% 41/2% Perineum 1% 9% 9% 9% 9% Anterior lower extremities 18% Anterior and posterior lower extremities 36% Posterior lower extremities 18% 100%

Calculations Calculate the TBSA using Rule of Nines: Arms (9% each = 18%) + Chest (18%) + Back (18%) + Head (9%) = 63% 2) Convert weight from pounds to kilograms: 180 lbs. x 1 kg/2.2 lbs. = 81.8 kg – round to 82 kg 3) Calculate fluids for the first 24 hours using the Parkland formula: 4 ml/kg x 82 kg. x 63 = 20,664 ml in first 24 hours. Give half within the first 8 hours post-injury; Give other half the remaining 16 hours If the injury occurred at 6:00 pm, 10,332 ml should be administered by 2:00 am. Then 10,332 ml should be administered 2:00 am - 6:00 pm.