chapter 5: the integumentary system. the structures and functions of the integumentary system

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Chapter 5: The Integumentary System

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  • Slide 1
  • Chapter 5: The Integumentary System
  • Slide 2
  • The structures and functions of the integumentary system.
  • Slide 3
  • Structure of the Integument 16% of body mass Composed of: 1.Cutaneous Membrane: 1.Epidermis Superficial epithelium 2.Dermis underlying CT with blood supply 2.Accessory Structures: originate in dermis 1.Hair 2.Nails 3.Exocrine Glands
  • Slide 4
  • Parts of the Integumentary System Figure 51
  • Slide 5
  • Functions of the Integument Protects underlying tissues from infection, exposure and dehydration Excretes salts, water, and organic waste Maintains normal body temp: - conserve and radiate heat Synthesizes Vitamin D3 for calcium metabolism Stores Nutrients and Fat Sensory detection: - touch, pressure, pain, and temp.
  • Slide 6
  • Connections Circulatory system: blood vessels in the dermis Nervous system: sensory receptors for pain, touch, and temperature
  • Slide 7
  • The main structures and functions of the epidermis.
  • Slide 8
  • Epidermis Avascular stratified squamous epithelium Nutrients and oxygen diffuse from capillaries in the dermis
  • Slide 9
  • Cells of the Epidermis Keratinocytes: contain large amounts of keratin the most abundant cells in the epidermis Thin Skin: Hairy Covers most of the body Has 4 layers of keratinocytes Thick Skin: No Hair Covers the palms of the hands and soles of the feet Has 5 layers of keratinocytes
  • Slide 10
  • Structures of the Epidermis The 5 strata of keratinocytes in thick skin Figure 53
  • Slide 11
  • Layers of the Epidermis From basal lamina to free surface: stratum germinativum stratum spinosum stratum granulosum stratum lucidum stratum corneum Transit from stratum basale to stratum corneum: 15-30 days Duration at stratum corneum: 7-14 days Complete turnover ever 25-45 days
  • Slide 12
  • 1. Stratum Germinativum/Basale The germinative layer: Single Layer has many germinative (stem) cells or basal cells is attached to basal lamina by hemidesmosomes forms a strong bond between epidermis and dermis Cells: basal/germinative cells (stem cells), melanocytes (melanin), some Merkel cells in hairless skin (touch receptors) Structure: Epidermal ridges (e.g., fingerprints) Dermal papillae (tiny mounds): increase the area of basal lamina strengthen attachment between epidermis and dermis
  • Slide 13
  • Layers of the Epidermis 2. Stratum Spinosum: 8-10 layers keratinocytes attached by desmosomes some cells can divide some Langerhans cells present (immune response) 3. Stratum Granulosum: 3-5 layers keratinocytes producing keratin fibers, keratohyaline granules, and lamellated granules Keratin = basic structural component of hair and nails Keratohyaline = Promotes dehydration of the cells and cross- linking of keratin fibers No cell division, nuclei and organelles being to disintegrate
  • Slide 14
  • Layers of the Epidermis 4. Stratum Lucidum: - thick skin only, flat packed keratin filled keratinocytes 5. Stratum Corneum: 15-30 layers dead keratinocytes that have been keratinized (cornified) Soft keratin fibers glued in paralled arrays by keratohyaline Extracellular space filled with glycolipids from lamellated granules Cornified = water and chemical resistant not water proof since interstitial fluid can evaporate
  • Slide 15
  • Ridges and Ducts Figure 54 The corrugated border between dermis and epidermis helps bond the epidermis and dermis - increased surface area for attachment In thick skin epidermal ridges show on the surface as fingerprints: Function enhance gripping
  • Slide 16
  • Dandruff is caused by excessive shedding of cells from the outer layer of skin in the scalp. Thus dandruff is composed of cells from which epidermal layer? 1.stratum germinativum 2.stratum spinosum 3.stratum corneum 4.stratum granulosum
  • Slide 17
  • A splinter that penetrates to the third layer of the epidermis of the palm is lodged in which layer? 1.stratum lucidum 2.stratum germinativum 3. stratum spinosum 4. stratum granulosum
  • Slide 18
  • Some criminals sand the tips of their fingers so as not to leave recognizable fingerprints. Would this practice permanently remove fingerprints? Why or why not? 1. Yes, because the dermal papillae die if exposed. 2. No, because the ridge patterns regenerate. 3. Yes, because the stratum germinativum thickens hiding ridge patterns. 4. No, because different ridge patterns will appear with re-growth.
  • Slide 19
  • Characteristics of Skin Skin is water resistant but not water proof: Insensible perspiration: Water from interstitial fluids evaporate Water loss can not be seen or felt water loss through skin: ~500ml (1 pint)/day More if damaged (e.g. burn) Sensible perspiration: Aware of water loss Produced by active sweat glands
  • Slide 20
  • Characteristics of Skin Callus: Thickening of skin, due to friction Blister: Separation of epidermal layers or epidermis form dermis space fills with interstitial fluid
  • Slide 21
  • Skin Color Pigment based: epidermal pigments and blood pigments contribute to the color 1.Epidermal Pigmentation 2.Dermal Circulation
  • Slide 22
  • Skin Color 1.Epidermal Pigmentation A. Carotene: yellow-orange, from diet - converted into Vitamin A - localized to epithelium - functions in normal maintenance of epithelia and photoreceptors - excess accumulates in stratum corneum B. Melanin: Brown, from melanocytes - for UV protection
  • Slide 23
  • 1. Epidermal Pigmentation Melanocytes: in stratum basale Synthesize melanin from tyrosine (amino acid) Packaged in melanosomes Melanosomes are transferred to cytoplasm of keratinocytes Cluster around top side of nucleus Eventually digested by lysosomes Everyone has ~1000 melanocytes/mm 2 Pale People: small melansomes, present on in stratum basale and spinosum Dark People: larger, greater number of melansomes, retained up through stratum granulosum
  • Slide 24
  • 1. Epidermal Pigmentation Freckles: Overproduction of melanin form single melanocytes UV exposure: Some needed for Vitamin D3 production Excess = damage (DNA mutation) Harm Fibroblasts impaired maintenance of the dermis resulting in altered CT structures Wrinkles Chromosomal damage of Epidermal cells or melanocytes cancer Squamous cell carcinoma Melanoma
  • Slide 25
  • Skin 2. Dermal Circulation: hemoglobin pigment - Oxygenated blood: - red color, hemoglobin in RBCs, through skin=pink - Vasodilation skin looks more red - Vasoconstriction skin looks more pale - Cyanosis: - low oxygen, blood deep purple, skin appears blue/purple - results form low temp., heart failure, asthma
  • Slide 26
  • Abnormal Skin Color Jaundice: Liver fails to excrete bile Bile accumulates in skin = yellow Addisons Disease: Pituitary secretes excess adrenocorticotropic hormone, stimulates melanoctyes, excess melanin, bronzing Albinism: Genetic mutation in melanin biosynthesis pathway Lack pigmentation in skin, hair and eyes Vitiligo: Autoimmune disease destruction of melanocytes
  • Slide 27
  • Vitamin D3 Production Cells of stratum spinosum and basale: UV energy + cholesterol = Vitamin D3 Vitamin D3: used by kidney to synthesize the hormone calcitriol Calcitriol: necessary to signal small intestine to absorb calcium No VitD no calcitriol no calcium absorption weak bones
  • Slide 28
  • KEY CONCEPT The epidermis: is a multilayered, flexible, self-repairing barrier prevents fluid loss protects from UV radiation produces vitamin D 3 resists abrasion, chemicals, and pathogens
  • Slide 29
  • Why does exposure to sunlight or sunlamps darken skin? 1. UV stimulates melanocytes. 2. Melanin darkens in sunlight. 3. Stratum corneum cells appear brown. 4. Keratin appears brown when heated.
  • Slide 30
  • Why does the skin of a fair-skinned person appear red during exercise in hot weather? 1. Sunlight stimulates erythrocyte production in skin. 2. Blood is diverted to the superficial dermis to eliminate heat. 3. Sunlight bleaches fair skin, allowing blood to be seen. 4. Heat stimulates cutaneous blood vessels, causing leaks.
  • Slide 31
  • In some cultures, women must be covered completely, except for their eyes, when they go outside. Explain why these women exhibit a high incidence of problems with their bones. 1. UV light prevents calcium deposition in bones. 2. Melanin production is necessary for bone growth. 3. Cloth prevents oxygen from diffusing into skin and bones. 4. UV light is necessary to produce the hormone cholecalciferol (vitamin D 3 ).
  • Slide 32
  • The structures and functions of the dermis.
  • Slide 33
  • The Dermis Is located between epidermis and subcutaneous layer Anchors epidermal accessory structures hair follicles, sweat glands Contains: All cells of CT proper, accessory organs of integument, blood vessels, lymphatic vessels, nerves, and sensory receptors Has 2 components: outer papillary layer deep reticular layer
  • Slide 34
  • Dermis Papillary layer: Thin (20%) Consists: Areolar CT Comprise dermal papillae Capillaries, lymphatics, and sensory neurons Function: feed epidermis Reticular Layer: Thick (80%) Consists: Dense irregular CT Elastic and Collagen fibers Function: provide strength and flexibility
  • Slide 35
  • Dermis Collagen fibers from reticular layer blend into papillary and subcutaneous layers to attach integument to body Wrinkles = Dermis stretched beyond its elastic capacity collagen fibers damaged Stretch marks = collagen and elastic fibers torn Thickened tissue resulting from pregnancy, weight gain, muscle gain Collagen and Elastin fibers arranged in parallel bundles: aligned to resist the expected direction of force = lines of cleavage Cuts parallel to lines of cleavage will heal faster and with less scar than those perpendicular
  • Slide 36
  • Lines of Cleavage Figure 57
  • Slide 37
  • Dermis Dermis highly vascularized: must feed itself and epidermis above Contusion: bruise, trauma that ruptures blood vessels but does not break skin, blood pools in dermis and must be removed by phagocytes (slow process)
  • Slide 38
  • Dermatitis An inflammation of the papillary layer Caused by infection, radiation, mechanical irritation, or chemicals (e.g., poison ivy) Characterized by itch or pain Characteristics Strong, due to collagen fibers Elastic, due to elastic fibers Flexible
  • Slide 39
  • Skin Damage Sagging and wrinkles (reduced skin elasticity) are caused by: dehydration age hormonal changes UV exposure
  • Slide 40
  • Sensory Perception in Integument Skin highly innervated for sensory perception, mostly in dermis 1.Merkel Cells 2.Free Nerve Endings 3.Meissners Corpuscles 4.Pacinian/Lamellated Corpuscles
  • Slide 41
  • Sensory Perception in Integument 1.Merkel cells: deep layers of epidermis - superficial touch 2.Free Nerve Endings: superficial dermis - pain and temperature 3.Meissners Corpuscles: superficial dermis - light tough 4.Pacinian/Lamellated Corpuscles: deep dermis - pressure and vibrations
  • Slide 42
  • Thick Skin Thin Skin
  • Slide 43
  • Where are the capillaries and sensory neurons that supply the epidermis located? 1. reticular layer of the dermis 2. epidermis 3. papillary layer of the dermis 4. hypodermic layer
  • Slide 44
  • What accounts for the ability of the dermis to undergo repeated stretching? 1. elastic fibers and skin turgor resilience 2. reticular fibers and fluids 3. adipocytes and elastic fibers 4. sebaceous gland secretions
  • Slide 45
  • The structures and functions of the subcutaneous layer.
  • Slide 46
  • The Hypodermis The subcutaneous layer or hypodermis: lies below the integument Not part of cutaneous membrane Stabilizes position of skin while permitting independent movement of skin and muscles
  • Slide 47
  • Subcutaneous Layer (aka Hypodermis) Areolar and adipose CT Tightly interwoven with reticular layer of dermis Children: even layer of adipose Puberty: Adipose shifts Male: neck, arms, abdomen, lower back Female: breast, buttocks, hips, thighs No vital organs: safe for SubQ injection, vascular for quick absorption
  • Slide 48
  • KEY CONCEPT The dermis: provides mechanical strength, flexibility and protection is highly vascularized contains many types of sensory receptors
  • Slide 49
  • Integumentary Accessory Structures 1.Hair and hair follicles 2.Sebaceous glands 3.Sweat glands 4.Nails Accessory Structures: are derived from embryonic epidermis are located in dermis project through the skin surface
  • Slide 50
  • Hair Human body: ~2.5 million hairs, 75% on body Everywhere except: palms, soles, lips, and certain genitalia Hair itself is dead, but is derived from live epidermal tissue Hair and Hair Follicle Structure
  • Slide 51
  • Hair growth, texture, and color.
  • Slide 52
  • Functions of Hair Function: Protects and insulates Guards openings against particles and insects Is sensitive to very light touch Structure of Hair Follicle: Hair Follicle Glassy membrane Hair bulb Hair papilla Hair Matrix Structure of Hair: Hair root Hair shaft
  • Slide 53
  • The Hair Follicle Hair is produced in organs called hair follicles Tube of stratified squamous epithelium anchored in dermis Surrounds, supports, and produces hair Two layers: Internal Root Sheath: contacts hair External Root Sheath: contacts glassy membrane
  • Slide 54
  • Hair Follicle Structure Glassy membrane Thick basal lamina between epithelial follicle and connective tissue dermis Hair bulb consist of epithelial cells Expanded base of follicle that surrounds papilla and matrix Responsible for producing hair by forming the hair matrix layer Hair Matrix Dividing epithelial/basal cells and melanocytes above papilla that form new hair Cells gradually push toward the surface Hair papilla CT at base of bulb, contains capillaries and nerves Supports matrix
  • Slide 55
  • Hair Structure Hair Root: Embedded in dermis Not yet fully formed Contains live cells Hair Shaft: Pokes through epidermis Fully organized dead hair Three layers 1.Cuticle: outermost, overlapping dead keratinized cells form shiny surface 2.Cortex: middle layer, dead cells contain hard keratin to provide stiffness 3.Medulla: core, dead cells contain soft keratin and air to provide flexible
  • Slide 56
  • Hair Structure Shape of the Shaft determines feel: Flattened shaft = kinky hair Oval shaft = silky and wavy hair Round shaft = straight and often stiff hair Two types of Hair produced: 1.Vellus Hairs = peach fuzz -Lacks medulla -Covers body, at puberty hormones can trigger switch to terminal hairs -Vellus hairs present at the armpits, pubic area, and limbs switch to terminal hairs in response to circulating sex hormones 2.Terminal Hairs = head, eyebrows and eyelashes - Thick, coarse, pigmented
  • Slide 57
  • Hair Color red: iron added Range yellow to black due to melanin from melanocytes in hair matrix Melanin stored in cortex and medulla With age, melanin declines, air pockets in medulla increase = gray or white hair
  • Slide 58
  • Hair Growth Hair in the Scalp: Grows for 2-5 yrs, at a rate of 0.33 mm per day During hair growth: Cells of the hair root absorb nutrients and incorporate them into the hair structure History of Exposure Result clipping or collecting hair for analysis is helpful in diagnosing several disorders (ex. Heavy Metals, nucleus = DNA) The root is firmly attached to the matrix of the follicle At the end of growth: The follicle becomes inactive termed club hair Follicle gets smaller Connections between the hair matrix and the club hair root breaks down. Another cycle begins: Follicle produces a new hair The old club hair is pushed to the surface and shed
  • Slide 59
  • Hair Growth ~0.33mm/day, not continuous: cycle of growth and rest 1.Active phase: - new hair added to hair root by dividing cells of hair matrix (weeks years) 2.Regressive phase: - cells of hair matrix stop dividing - hair root and hair papilla separate loose hair = club hair 3.Resting phase: - cells of hair matrix and hair follicle remain inactive (1-3 months) New Active Phase Begins Hair length differences = difference in time spent in active phase: eyebrows = few months head many years
  • Slide 60
  • Shedding of the hair occurs only after the next growth cycle begins and a new hair shaft begins to emerge. On average 50 - 100 hairs are shed every day. The percentage of follicles in the resting phase will vary at any time depending on the body area. Factors that can affect the hair growth cycle and cause temporary or permanent hair loss (alopecia) including: medication, radiation, chemotherapy, exposure to chemicals, hormonal and nutritional factors, thyroid disease, generalized or local skin disease, stress, and high fevers.
  • Slide 61
  • Hair Growth Alopecia: Shift from terminal hair to vellus hair, thinning/balding, some degree expected with age Male Pattern Baldness: Genetic alopecia, early age onset Caused by a shift from terminal to vellus hair production due to a change in the level of sex hormones circulating in the blood Treatment: Aimed at converting vellus hairs to terminal hairs Hair Removal: Difficult to achieve permanent result Any remaining matrix cells can regenerate all hair follicle structures
  • Slide 62
  • Hair Function Head: UV protection Cushion from trauma Insulation Nostrils, Ear canals, Eyelashes: Prevent entry of foreign material Body Hair: sensory detection
  • Slide 63
  • Hair Function: Sensory Detection Root hair plexus: Sensory nerves at base of hair follicle that detect slight movement of hair Arrector pili muscle: Attached to every hair follicle Contract to stand hair perpendicular to skin surface Goose bumps Smooth muscle: involuntary
  • Slide 64
  • What happens when the arrector pili muscle contracts? 1.Sebum is released. 2. Goose bumps are evident. 3. Sweat is produced. 4. Blood flow is increased.
  • Slide 65
  • Once a burn on the forearm that destroys the epidermis, and extensive areas of the deep dermis heals, will hair grow again in the affected area? 1. Yes. 2. No. 3. Only in areas where the deep dermis was destroyed. 4. Only in areas where the epidermis and deep dermis were not destroyed.
  • Slide 66
  • The skin glands and secretions.
  • Slide 67
  • Exocrine Glands Sebaceous glands (oil glands): holocrine glands (which destroys gland cells) secrete sebum Sudoriferous Glands/Sweat Glands A. Merocrine/Eccrine sudoriferous glands B. Apocrine sudoriferous/sweat gland Sweat glands: merocrine glands watery secretions
  • Slide 68
  • Integumentary Glands All are exocrine glands Secrete product onto skin surface via a duct 1.Sebaceous glands -Holocrine secretion -Secrete sebum into hair follicle -Sebum = lipids + cholesterol + proteins + electrolytes -Function: -Lubricate and protect keratin -Prevent evaporation -Inhibit bacterial growth Sebaceous glands active in fetus, then off until puberty, and then back on for the whole adult life Acne = Inflammation of a sebaceous gland, * Usually due to bacterial infection
  • Slide 69
  • Integumentary Glands 2. Sudoriferous Glands/Sweat Glands A. Merocrine/Eccrine sudoriferous glands - 2 to 5 million all over body - produce sensible perspiration: - 99% water - electrolytes + organic nutrients + antibodies + antimicrobial agents + organic waters - merocrine secretion - secretion via exocytosis of vesicles - small coiled tubular glands - located in superficial dermis - open directly on surface of skin - secrete in response to high temp. or stress
  • Slide 70
  • Functions of Sensible Perspiration 1.Evaporation cooling of surface of skin to reduce body temp. 2.Excrete waste electrolytes and drugs 3.Protection: -Prevent adherence of microbes: antibodies -Physically wash off microbes -Antimicrobial agents of kill microbes -Dermiciden (antibiotic)
  • Slide 71
  • Integumentary Glands 2. Sudoriferous Glands/Sweat Glands B. Apocrine sudoriferous/sweat gland - merocrine secretion - armpits, nipples, groin - secrete into hair follicle - secretion is stick and cloudy: - sensible perspiration + protein + lipids - microbes eat it wastes = body odor - glands deep in dermis - Surrounded by myoepithelial cells: myo = muscle - contraction of cells in response to sympathetic nervous system stimulation causes discharge of secretion - Active only after puberty Special Apocrine Sweat Glands: 1. Mammary Glands: - Located in female breast & Secrete milk during lactation 2. Ceruminous Glands: - Located in external ear canal & Secrete cerumen (earwax)
  • Slide 72
  • Integumentary Gland Control Merocrine sudoriferous glands: can be turned on and off in localized regions in response to temperature or emotions Sebaceous and apocrine sudoriferous glands: Autonomic nervous system controls the activation and deactivation of these glands therefore they affect all the glands are either all on (body wide) or all off no local control
  • Slide 73
  • What are the functions of sebaceous secretions? 1.inhibits the growth of bacteria 2. lubricates and conditions the surrounding skin 3. lubricates and protects the keratin of the hair shaft 4. all of the above
  • Slide 74
  • Deodorants are used to mask the effects of secretions from which type of skin gland? 1. ceruminous glands 2. apocrine sweat glands 3. merocrine sweat glands 4. mammary glands
  • Slide 75
  • Which type of skin glands are most affected by the hormonal changes that occur during puberty? 1. ceruminous glands 2. sebaceous glands 3. apocrine sweat glands 4. merocrine sweat glands
  • Slide 76
  • The structure of nails.
  • Slide 77
  • Nails Scale like projections on dorsal surface of distal digits Function: protect tips from mechanical stress, assist in gripping Consists of dead cells containing hard keratin New nail formed at nail root Cuticle = stratum corneum Nail growth is continuous
  • Slide 78
  • How injured skin responds and repair itself.
  • Slide 79
  • Injury and Repair Integument can function independent of nervous and endocrine systems to maintain own homeostasis Mesenchymal cells of dermis can regenerate connective tissue Germinative cells (basal cells) of epidermis can regenerate tissue
  • Slide 80
  • Repair of Localized Injuries to the Skin: Step 1 Bleeding occurs Mast cells trigger inflammatory response Figure 513 (Step 1)
  • Slide 81
  • Repair of Localized Injuries to the Skin: Step 2 A scab stabilizes and protects the area Figure 513 (Step 2)
  • Slide 82
  • The Inflammatory Response Germinative cells migrate around the wound Macrophages clean the area Fibroblasts and endothelial cells move in, producing granulation tissue
  • Slide 83
  • Repair of Localized Injuries to the Skin: Step 3 Fibroblasts produce scar tissue Inflammation decreases, clot disintegrates Figure 513 (Step 3)
  • Slide 84
  • Repair of Localized Injuries to the Skin: Step 4 Fibroblasts strengthen scar tissue A raised keloid forms Figure 513 (Step 4)
  • Slide 85
  • Injury and Repair Repair may end up like original tissue or keloid Keloid = thick area of scar tissue covered by smooth epidermis Burns: First degree burn: heals on own Damage to surface of epidermis Second degree burn: heals on own Damage to epidermis and superficial dermis Third degree burn: Requires skin grafts or living bandages Damage to whole cutaneous layer (epidermis, dermis, accessory structures), granulation tissue cannot form thus no healing
  • Slide 86
  • Burns If burn > 20% of body can kill It affects: 1.Fluid and electrolyte balance 2.Thermoregulation 3.Protection from pathogens
  • Slide 87
  • What do you call the combination of fibrin clots, fibroblasts, and the extensive network of capillaries in healing tissue? 1. granulation tissue 2. scar 3. scab 4. callus
  • Slide 88
  • Why can skin regenerate effectively, even after considerable damage? 1.Stratum germinativum persists deep within the body. 2. Stem cells persist in all components of the skin. 3. Hypodermis will transform into epidermis and dermis. 4. Surrounding skin spreads and fills in damaged area.
  • Slide 89
  • The effects of aging on the skin.
  • Slide 90
  • Age Related Changes 1.Stem cell activity declines: -Skin thin, repair is difficult 2.Langerhans cells decrease: - Reduced immune response 3.Vitamin D3 production declines: -Calcium absorption declines brittle bones 4.Glandular activity declines: - skin dry, body can overheat 5.Bloody supply to dermis declines: - tend to feel cold 6.Hair follicles die or produce thinner hair: - terminal vellus 7.Dermis thins and becomes less elastic wrinkles 8.Sex characteristics fade: - Fat deposits spread out, hair patterns change
  • Slide 91
  • Older individuals do not tolerate the summer heat as well as they did when they were young, and they are more prone to heat-related illness. What accounts for these changes? 1. Blood supply to the dermis is reduced. 2. Glandular activity declines. 3. Melanocyte activity declines. 4. All of the above.
  • Slide 92
  • The integumentary system work with other systems.
  • Slide 93
  • Importance of the Integumentary System Protects and interacts with all organ systems Changes in skin appearance are used to diagnose disorders in other systems
  • Slide 94
  • Interactions with the Integumentary System Figure 515
  • Slide 95
  • SUMMARY Division of: integument into epidermis and dermis epidermis into thin skin and thick skin Layers of the epidermis: stratum germinosum stratum spinosum stratum lucidum stratum corneum Roles of epidermal ridges and dermal papillae Functions of specialized cells: Langerhans cells & Merkel cells
  • Slide 96
  • SUMMARY Skin pigments: Carotene & Melanin Metabolic functions of epidermis: vitamin D 3 & epidermal growth factor Divisions of the dermis: papillary layer reticular layer Mobility of the dermis: stretch marks & lines of cleavage Blood supply of the dermis: cutaneous plexus papillary plexus
  • Slide 97
  • SUMMARY Role of the subcutaneous layer Structure of hair and hair follicles Glands of the skin: sebaceous sweat Ceruminous Structure of nails Processes of inflammation and regeneration Effects of aging on the integument