CHAPTER 6 INTEGUMENTARY SYSTEM 1 Integumentary System Essential

CHAPTER 6 INTEGUMENTARY SYSTEM 1

Integumentary System: Essential Learning(s) Skin and Its Tissues ü List the general functions of the skin. ü Describe the structure of the layers of skin. ü Summarize the factors that determine skin color. Accessory Structures of the Skin ü Describe the accessory structures associated with the skin. ü Explain the functions of each accessory structure of the skin. 2

Integumentary System: Essential Learning(s) Regulation of Body Temperature ü Explain how the skin helps regulate body temperature. Healing of Wounds and Burns ü Describe the events that are part of wound healing. ü Distinguish among the types of burns, including a description of healing with each type. Lifespan Changes ü Summarize lifespan changes in the integumentary system. 3

Levels of Organization Copyright © The Mc. Graw-Hill Companies, Inc. Permission required for reproduction or display. Subatomic particles Atom Organ system Molecule Macromolecule Organelle Organism Cell Tissue

Introduction: Integumentary System • Two or more kinds of tissues grouped together and performing specialized functions constitutes an organ. • The integumentary system consists of a major organ, skin, and many epidermal derivatives (accessory struc) which include hair follicles, sebaceous glands, sweat glands, and nails. What is the function of the skin? What does it do? 5

Skin and Its Functions q Protection: Physical barrier a. From water loss b. From injury c. From chemicals and microorganisms Chemical barrier a. ph of 5 – 6 b. Prohibits microbial growth Biological barrier a. Langerhan’s cells (epidermis) – function with leukocytes to trigger immune reactions b. Macrophages and mast cells (dermis) 6

Skin and Its Functions q Protection: Surface film – produced by the mixing of residue and secretions from sweat and sebaceous glands with epithelial cells constantly being cast off from the epidermis Functions: Antibacterial and antifungal activity Lubrication Hydration of skin surface Buffering of caustic irritants Blockage of many toxic agents 7

Skin and Its Functions q Excretion: (minimal, most through kidneys!) through sweat - urea and uric acid q Regulation of Body Temperature recall negative feedback mechanism from Ch. 1 q Cutaneous Sensation Light touch detection = tactile (Meissner’s) corpuscles a. egg-shaped b. Located in dermal papillae c. populate areas in the fingertips, palms, soles, eyelids, tip of the tongue, nipples, clitoris, and tip of penis Pressure detection = lamellated (Pacinian) corpuscles a. Onion-shaped 8

Skin and Its Functions q Vitamin D synthesis: UV rays in sunlight activate its synthesis Vitamin D is required for bone homeostasis q Blood Reservoir: The dermis houses about 10% of the body’s blood vessels Skin only requires 1 – 2% of the body’s blood q Immunity: Langerhan’s cells (macrophages) interact with T-helper cells in immune responses 9

Layers of Skin • Epidermis - outermost layer of cells • Dermis - inner layer • Subcutaneous layer adipose tissue • A. k. a hypodermis • Beneath dermis Stratified squamous epithelium Dense irregular connective tissue Adipose tissue 10

Epidermis • Structure = keratinized stratified squamous epithelium • Function = Protection (keratin) prevents water loss; prevents injury by penetration; prevents microbe/chemical entry Hair shaft Sweat gland pore Sweat Stratum corneum Epidermis Stratum basale Capillary Dermal papilla Basement membrane TTactile (Meissner’s) corpuscle Dermis Sebaceous gland Arrector pili muscle Sweat gland duct Lamellated (Pacinian) corpuscle Hair follicle • Pigment = melanin determines skin color produced by melanocytes in stratum basale o genetic factors o environmental factors o physiological factors Sweat gland Subcutaneous layer Nerve cell process Adipose tissue Blood vessels Muscle layer (a) Hair shaft Epidermis Dermis Hair follicle Sebaceous gland (b) b: © Victor Eroschenko 11

Epidermis There are five (5) layers of the epidermis: • Stratum corneum – outermost layer • Stratum lucidum (only in thick skin – palms, soles) • Stratum granulosum – 3 -5 layers of flattened granular cells (keratin) • Stratum spinosum - many layers of spiky cells w/ large nuclei • Stratum basale – innermost layer (directly above basement mem) * Together the spinosum and basale make up the stratum germinativum Stratum corneum Stratum lucidum Stratum granulosum Stratum spinosum Stratum basale Basement membrane Dermal papilla Dermis (a) (b) 12

Epidermis q Structure = keratinized stratified squamous epithelium q Four distinct layers each determined by the extent of keratinization in the epithelial cells: Stratum corneum = outermost layer dead epithelial cells filled with the protein keratin Stratum lucidum = translucent layer separating s. corn & s. gran extra layer only in thick skin of soles & palms Stratum granulosum = composed of 3 -5 layers of flattened granular cells (filled w/ keratin granules) Stratum spinosum = composed of many layers of “spikey” cells with large nuclei Stratum basale = innermost layer; directly above basement m. 13

Epidermis q. Pigment = melanin a) determines skin color b) produced by melanocytes in s. basale q Heredity and environment determine skin color q Genetic Factors • Varying amounts of q Physiological Factors melanin • Carotene may accumulate in • Varying size of melanin s. corneum = orange granules • Hb in dermal b vessels = pink • Albinos lack melanin • Lack of Hb = blue (cyanosis) q Environmental Factors • Inability to breakdown Hb • Sunlight (liver problem) = yellow • UV light from sunlamps • X-rays • Darkens melanin 14

Dermis q inner layer of skin; binds epidermis to underlying tissues q. Structure: A. two distinct layers 1) papillary layer 2) reticular layer B. houses epidermal derivatives or accessory structures Epidermis Hair shaft Sweat gland pore Sweat Stratum corneum Stratum basale Capillary Dermal papilla Basement membrane Ex. nails, hair follicles and skin glands Dermis Subcutaneous layer q Functions: A. nourishment of epidermis B. provides strength/flexibility Tactile (Meissner’s) corpuscle Sebaceous gland Arrector pili muscle Sweat gland duct Lamellated (Pacinian) corpuscle Hair follicle Sweat gland Nerve cell process Adipose tissue Blood vessels Muscle layer (a) 15

Accessory structures of the Skin q Nails: 1. structure: epithelia undergoing keratinization (mitotically active in lunula) 2. functions: a. manipulation b. protection of ends of digits q Hair follicles: 1. structure: a. root or base in deep dermis b. follicle throughout dermis c. shaft in epidermis extending beyond the surface 16

Accessory structures of the Skin q Hair follicles: cont 2. Keratinization a. cell are epithelium b. cells in root = mitotically active c. cells in follicle = maturing & accum. keratin d. cells in epidermis = dead epith. cells; full of keratin = exposed hair or hair shaft 3. Pigment = melanin a. albinism = lack of melanin b. red hair = trichosiderin 4. Arrector pili muscle = bundle of smooth muscle assoc. w/ every hair follicle a. causes hair to stand on end when frightened or cold 17 = “goose bump”

Accessory structures of the Skin q Skin glands: 1. Sebaceous glands Structure: a. holocrine gland (simple cuboidal epith. ) b. assoc w/ every hair follicle c. secretion = sebum (ie. oil) fat and cell material sebum is secreted into hair follicle Function: a. sebum keeps skin/hair soft, pliable, & waterproof Disorders: a. acne (hypersecretion sebum; ducts clog & inflame) b. seborrhea (hyperprod of sebum; oily scales) 18

Accessory structures of the Skin q Skin glands: cont 2. Sweat glands & sudoriferous glands * Two types (based on glandular secretion) a. Merocrine (eccrine) glands Structure: coil in deep dermis; duct in dermis; pore at surface Characteristics: respond to elevated temp/exercise; no odor in secretion; function throughout life; not assoc w/ hair follicle Location: forehead; neck; back Secretion: water + salts + waste (urea/uric acid) 19

Accessory structures of the Skin q Skin glands: cont 2. Sweat glands & suboriferous glands b. Apocrine glands Structure: ducts terminate into fair follicles Characteristics: respond to stress/emotions; odor in secretion; function at puberty/continue thru life; assoc w/ hair follicles Location: armpits & groin Secretion: sweat (as above) + oil + cellular debris Modified Apocrine glands: ceruminous gland=ear wax mammary gland=milk 20

Dermis q. Two layers of the dermis: 1) Papillary layer (20%) a. superficial = below epidermis b. loose areolar CT c. dermal papillae here form fingerprints in thick skin d. Meissner’s corpuscles - light touch receptor Papillary layer 2) Reticular layer (80%) a. collagen/elastic/reticular fibers = strength & resiliency b. cleavage, tension or Langer’s lines are here c. Lamellated (Pacinian) corpuscles – deep pressure receptors Reticular layer (a) 21

Subcutaneous Layer q Hypodermis Copyright © The Mc. Graw-Hill Companies, Inc. Permission required for reproduction or display. q Structure: Loose connective tissue and adipose tissue Epidermis Dermis q Function: Insulates Hair shaft Sweat gland pore Sweat Stratum corneum Stratum basale Capillary Dermal papilla Basement membrane Tactile (Meissner’s) corpuscle 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 q Major blood vessels present (a) 22

Hair Follicles Copyright © The Mc. Graw-Hill Companies, Inc. Permission required for reproduction or display. • Epidermal cells • Tube-like depression • Extends into dermis • Three (3) parts: • Hair root • Hair shaft • Hair papilla Hair shaft Pore Sebaceous gland Arrector pili muscle Hair root (keratinized cells) Hair follicle Eccrine sweat gland • Dead epidermal cells • Melanin • Arrector pili muscle Region of cell division Hair papilla Dermal blood vessels (a) 23

Nails q Function: protective covering Lunula Nail bed Nail plate q Structure: Three (3) parts: Nail plate Lunula Nail bed 24

Sebaceous Glands Copyright © The Mc. Graw-Hill Companies, Inc. Permission required for reproduction or display. q Usually associated w/ hair follicles Sebaceous gland Hair follicle q Holocrine glands q Secrete sebum (oil) Hair q Absent on palms and soles © Per H. Kjeldsen 25

Sweat Glands Copyright © The Mc. Graw-Hill Companies, Inc. Permission required for reproduction or display. • A. k. a sudoriferous glands • Widespread in skin Hair shaft • Originates in deeper dermis or hypodermis • Eccrine glands • Apocrine glands • Ceruminous glands • Mammary glands Pore Dermal papilla Sebaceous gland Duct Hair follicle Eccrine sweat gland Apocrine sweat gland 26

Regulation of Body Temperature q 1. Regulation of body temperature is vitally important because even slight shifts can disrupt metabolic reactions * Heat production is mostly a by-product of cellular metabolism q 2. Heat loss controlled by regulating dermal blood flow a. vasodilation – increases dermal blood flow = incr. heat loss b. vasoconstriction – decreases dbf = decr. Heat loss q 3. Four methods of heat loss a. radiation – most heat loss; infrared heat rays move from area of high heat (blood) to low heat (environ) b. conduction – less heat loss; heat moves by phys contact c. convection – heat loss to surrounding air; incr. as air moves d. evaporation – heat loss varies; if heat incr. sweating incr. lose heat by sweat evaporating on skin 27

Regulation of Body Temperature q 4. Low body temperature requires heat loss to be minimized a. the hypothalamus signals for sweating to decrease (decreasing heat loss by evaporation) and dermal vasoconstriction (decreasing heat loss by radiation) b. usu. brings body temp back to normal q 5. If body temp remains low (after the above action) a. heat must be produced b. shivering occurs and the tiny muscle contrations involved produce heat 28

Regulation of Body Temperature q Problems in Temperature Regulation 1. Hyperthermia = elevated body temperature requires heat to be dissapated a. Two common causes: 1. humid air decreases evaporation 2. air temp exceeds body temperature heat is gained/ not lost 2. Hypothermia = low body temperature a. very dangerous is core temp. drops below 94 F b. limbs can withstand 65 F because they contain no vital organs c. intentional during some surgical procedures 29

Regulation of Body Temperature Copyright © The Mc. Graw-Hill Companies, Inc. Permission required for reproduction or display. Control center Hypothalamus detects the deviation from the set point and signals effector organs. Receptors Thermoreceptors send signals to the control center. Effectors Dermal blood vessels dilate and sweat glands secrete. Stimulus Body temperature rises above normal. Response Body heat is lost to surroundings, temperature drops toward normal. too high Normal body temperature 37°C (98. 6°F) too low Stimulus Body temperature drops below normal. Receptors Thermoreceptors send signals to the control center. Response Body heat is conserved, temperature rises toward normal. Effectors Dermal blood vessels constrict and sweat glands remain inactive. Control center Hypothalamus detects the deviation from the set point and signals effector organs. Effectors Dermal blood vessels constrict and sweat glands remain inactive. If body temperature continues to drop, control center signals muscles to contract involuntarily. 30

Healing of Wounds and Burns q A. Cuts 1. Epidermal cuts are closed by increased cell division in the stratum basale 2. Deep cuts involve blood vessel damage resulting in: a. inflammation b. blood clotting c. scab formation d. fibroblast infiltration e. scab falls off f. scar may or may not form q B. Burns 1. superficial partial- thickness burns (1 st degree) a. epidermis only b. reddening due to increased blood flow c. mild pain d. common in sunburn e. heals in a few days to 2 weeks 31

Healing of Wounds and Burns q B. Burns (cont) 2. Deep partial-thickness burns (2 nd degree) a. epidermis & some dermal damage b. reddening and blistering (blood vessel damage) c. moderate pain d. common to physical contact w/ hot objects e. heals in 2 -6 weeks w/0 scars unless infected 3. Full-thickness burns (3 rd degree) a. epid. , derm. , and subcutaneal damage b. dry, leathery tissue w/ red or black color c. severe pain d. caused by prolonged heat or chemical contact e. healing rarely occurs due to lack of surviving skin cells; grafts needed; usually extensive scarring 32

Healing of Wounds and Burns q B. Burns…cont 3. Full-thickness burns (3 rd degree) f. autograft – transplant from undamaged area of self g. homograft – temporary transplant from cadaver 4. Body surface affected a. estimated by “rule of nines” b. important for determining treatment/prognosis 33

Copyright © The Mc. Graw-Hill Companies, Inc. Permission required for reproduction or display. Site of injury Blood cells (a) (b) Scab Blood clot (c) (d) (e) Scab Scar tissue Fibroblasts (f) (g) 34

Rule of Nines for Adults 41/2% Anterior and posterior head and neck 9% 41/2% Anterior head and neck 4 1/2% Anterior trunk 18% Anterior and posterior upper extremities 18% Anterior upper extremities 9% 41/2% Anterior and posterior trunk 36% Posterior head and neck 4 1/2% Posterior trunk 18% Posterior upper extremities 9% 41/2% Perineum 1% 9% Anterior lower extremities 18% 9% 9% Anterior and posterior lower extremities 36% 100% 9% Posterior lower extremities 18% 35

Lifespan Changes q A. Aging skin exhibits: 1. wrinkling a. some individuals choose “botox” injections to temp reduce wrinkles 2. sagging 3. age spots or liver spots B. Efficient regulation of body temperature declines w/ age 1. number of sweat glands changes 2. capillary beds in the skin shrink C. Synthesis of vit. D declines as skin ages, which affects skeletal health = ex. osteoporosis 36

Lifespan 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 decreases • Nail growth becomes impaired • Sensory receptors decline • Body temperature unable to be controlled • Diminished ability to activate Vitamin D 37