Chap06 Integumentary System
- 2. 6-2 The Integumentary System • Functions of the skin and subcutaneous tissue – epidermis and dermis – hypodermis – thick and thin skin – skin color – skin markings • Hair and nails • Cutaneous glands • Skin disorders
- 3. 6-3 Skin & Subcutaneous Tissue • The bodies largest organ and constitutes 15% of body weight. – i.e. 150 pound person = 22.5 pounds is skin. • Every 24 hours, the surface of the skin sheds a layer of dead cells, constantly renewing about every 28 days • An average of 40 kilos of skin is shed during a lifetime
- 4. 6-4 Overview Skin consists of two layers: • Epidermis –Keratinized stratified squamous epithelium • Dermis –connective tissue layer • Hypodermis- not part of skin but studied • Thickness variable, normally 1-2 mm (0.03) - Lacks hair follicles or sebaceous glands, –Thickness due to dermis, up to 6 mm (0.24 inches) – thin skin contains hair follicles, sebaceous & sweat glands
- 5. 6-5 Structure of the Skin
- 6. 6-6 Functions of the Skin 1. Resistance to trauma and infection – packed with keratin and linked by desmosomes; – Bacteria & fungi are kept in check by the dryness & acid mantle (pH 4-6) of skin; 1. Barrier - to ultraviolet light, H2O lose & absorption, permeable to some drugs & poisons; 2. Vitamin D synthesis- first step 3. Sensory receptors – heat, cold, texture, pressure, vibration, injury 4. Thermoregulation- through sweating, thermoreceptors 5. Nonverbal communication
- 7. 6-7 Transdermal Absorption The ability to absorb substances through the skin: - medicine - ointments (hydrocortisone) - lotions - adhesive patches (ADHD, nitroglycerine) - poisons - toxic alkaloids (poison ivy) - mercury, lead, arsenic, carbon tetrachloride - acetone (nail cleaner) Causes- liver, kidney failure, brain damage.
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- 9. 6-9 Cells of the Epidermis Most epidermis cells are keratinized, stratified squamous, which mean: Flat, layered cells that contain dead cells packed with tough protein keratin Like other epithelia the Epidermis lack a blood supply, and must depend upon diffusion from the underlying connective tissue.
- 10. 6-10 Cells of the Epidermis Composed of 5 types of cells: – undifferentiated cells in deepest layers (ONLY Stratum basale); – Undergo mitosis to give rise to keratinocytes; -most of the skin cells, synthesis keratin; -ONLY in Stratum basale, synthesize melanin that shield UV; – Receptors for touch,cells associated with nerve fibers – macrophages guard against pathogens, toxins; – Found in Stratum spinosum & stratum granulosum layer; 1. Stem Cells 2. Keratinocytes 3. Melanocytes 4. Tactile (merkel) cells 5. Dendritic (langerhans) cells
- 11. 6-11 Cells of the Epidermis
- 12. 6-12 Layers of the Epidermis • The epidermis is made up of 4-5 (thick) layers of cells.
- 13. 6-13 1. Stratum Basale • Single layer cells on basement membrane (usually cuboidal) • Cell types in this layer • undergo mitosis to replace epidermis • distribute melanin through cell processes • melanin picked up by keratinocytes - are touch receptors • form Merkel disc Layers of Epidermis 1. Stem Cells 3. merkel cells 2. melanocytes
- 14. 6-14 2. Stratum Spinosum • Several layers of keratinocytes (thickest layer) – Lowest layer capable of mitosis but as they are pushed upward, they instead produce keratin filaments that flatten out the cells as they move to surface. • Contains: – macrophages from bone marrow that migrate to the epidermis – 800 cells/millimeter2 – help protect body against pathogens by “presenting” them to the immune system Dendritic (Langerhans) Cells
- 15. 6-15 3. Stratum Granulosum 3 to 5 layers Flat keratinocytes • Contain keratinohyalin granules – Produces lipid-filled vesicles that release a glycolipid by exocytosis to waterproof the skin • forms a barrier between surface cells and deeper layers of the epidermis
- 16. 6-16 4. Stratum Lucidum • Thin translucent zone seen only in thick skin • Keratinocytes are packed with eleidin, a precursor to keratin – does not stain well • Cells have no nucleus or organelles
- 17. 6-17 5. Stratum Corneum • Up to 30 layers of dead, scaly, keratinized cells – surface cells flake off (exfoliate) – Especially resistant to abrasion, penetration, and water loss
- 18. 6-18 Layers & Cells of Epidermis
- 19. 6-19 Canadian Ladies Give Superb Backrubs {corneum, lucidum, granulosum, spinosum, basale}
- 20. 6-20 Life History of Keratinocytes • Produced by stem cells in stratum basale • New cells push others toward surface – 30 to 40 days keratinocytes make their way to the surface and flake off. – Accelerated growth = calus or corn – As they get closer to the surface the form a membrane-coating vesicle. • Keratinocytes in the S. granulosum layer • Undergo apopthosis • The keratohylin granules release their substance • Membrane coating vesicles release a lipid mixture • Epidermal water barrier forms between S. granulosum and S. spinosum • Retains water in the body and prevents dehydration. – Cells above the barrier are cut off from nutrients die.
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- 23. 6-23 Dermis • Is a connective tissue layer – Composition • collagen, elastic and reticular fibers, fibroblasts • Well supplied with blood vessels, nerve endings, sebaceous glands, sweat glands, hair follicles, smooth muscles (Piloerector), skeletal muscles allow for facial expression, smiles etc.
- 24. 6-24 Dermis • Dermal papillae - extensions of the dermis into the epidermis • Epidermal ridges – extension of epidermis into dermis – forming the ridges of the fingerprints
- 25. 6-25 Dermis • Dermis contains two zones (layers) – papillary layer: loosely organized areolar tissue allows motility of leukocytes and other defense against breaks in epidermis. – reticular layer: contains dense irregular connective tissue. Excessive stretch can tear these fibers producing Striae (stretch marks)
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- 28. 6-28 Hypodermis • Aka Subcutaneous tissue/ superficial fascia • Mostly adipose (subcutaneous fat) and areolar, distribution is different throughout the body and sexes. • Functions – energy reservoir – thermal insulation • Hypodermic injections (subQ) – highly vascular
- 29. 6-29 Stratification of the Skin & Hypodermis
- 30. 6-30 Review
- 31. 6-31 Skin Color
- 32. 6-32 Skin Colors (Pigmentation) • Main factor is Melanin • Produced by melanocytes, accumulates in the keratinocytes in the S.basale and S. Spinosum.
- 33. 6-33 Melanin • 2 Forms: 1. Eumelanin: brownish – black 2. Pheomelanin: reddish yellow pigment All races generally have the same number of melanocytes, but in darker skinned people melanocytes produce a greater amount of melanin, conversely lighter skinned people do not. Location of melanin in the body may differ in regions. Other factors in skin color: Hemoglobin: imparts a reddish to pinkish hues to the skin. Carotene: a yellow pigment found in egg yolks and yellow orange vegetable.
- 34. 6-34 Abnormal Skin Colors Abnormal Color for diagnosis • Cyanosis = blueness from deficiency of oxygen in the circulating blood (cold weather) • Erythema = redness due to dilated cutaneous vessels (anger, sunburn, embarrassment) • Jaundice = yellowing of skin and sclera due to excess of bilirubin in blood (liver disease)
- 35. 6-35 Abnormal Skin Colors • Bronzing = golden-brown color of Addison disease (deficiency of glucocorticoid hormone) • Pallor = pale color from lack of blood flow • Albinism = a genetic lack of melanin • Hematoma = a bruise (visible clotted blood)
- 36. 6-36 • Freckles and moles = aggregations of melanocytes – freckles are flat; moles are elevated • Friction ridges leave oily fingerprints on touched surfaces – unique pattern formed during fetal development • Flexion creases form after birth by repeated closing of the hand • Flexion lines form in wrist and elbow areas Skin Markings
- 37. 6-37 Skin Markings • Hemangiomas (birthmarks) – discolored skin caused by benign tumors of dermal blood capillaries • Types: – Capillary Hemangiomas (strawberry birthmarks): bright red or purple, disappear in childhood. – Cavernous Hemangiomas (port wine stains): flat and duller in color last for life
- 38. 6-38 Hair
- 39. 6-39 Characteristics of Human Hair • Hair: composed of dead, keratinized cells • Hair found almost everywhere – The number of hairs on a given area does not differ much from person to person – differences between sexes or individuals is difference in texture and color of hair • 3 different body hair types – lanugo -- fine, unpigmented fetal hair, last 3 months – vellus -- fine, unpigmented hair of children and women – terminal hair -- coarse, long, pigmented hair of scalp
- 40. 6-40 Structure of Hair and Follicle Hair divided into 3 zones along its length: 1. Bulb: 2. Root: 3. Shaft: Swelling at base where hair originates in dermis Remainder of the hair within the follicle Portion above the skin
- 41. 6-41 Structure of Hair and Follicle Cross section shows 3 layer within hair: 1. Medulla: 2. Cortex: 3. Cuticle: Loosely arranged cells, air space found in thick hair but absent from thin hair. Layer of keratinized cuboidal cells Surface layer of scaly cells
- 42. 6-42 Hair Texture & Color Texture is related to cross-sectional shape. • Straight hair is round. • Wavy hair is oval. • Tight curly hair is relatively flat. Color is due to pigment granules in the cells of the cortex.
- 43. 6-43Eumelanin pigment colors brown and black hair. Hair Color and Texture, Brunette
- 44. 6-44 Blond hair contain pheomelanin pigment, but little eumelanin. Hair Color and Texture, Blonde
- 45. 6-45 Red hair contains little eumelanin but lots of pheomelanin. Hair Color and Texture, Red
- 46. 6-46 White & Gray hair = air in medulla and lack of pigment in cortex. Hair Color and Texture, Gray and White
- 47. 6-47 Functions of Hair 1. Body hair (too thin to provide warmth) – alert us to parasites crawling on skin (lice,fleas) 1. Scalp hair – heat retention and sunburn cover 1. Beard, pubic and axillary hair indicate sexual maturity and help distribute sexual scents 2. Guard hairs (vibrissae) and eyelashes 1. prevent foreign objects from getting into nostrils, ear canals or eyes • Expression of emotions with eyebrows
- 48. 6-48 Nails
- 50. 6-50 Nails • Derivative of stratum corneum – densely packed dead cells filled with hard keratin • Flat nails allow for fleshy, sensitive fingertips • Growth rate is 1 mm per week – new cells added by mitosis in the nail matrix (under skin) – nail plate is visible part of nail • medical diagnosis of iron deficiency = concave nails • Finger nails can become clubbed in long term hypoxia (O2 deficiency in blood) such as congenital heart defects.
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- 53. 6-53 Cutaneous Glands Skin has 5 types of glands: Merocrine Sweat Glands Apocrine Sweat Glands Sebaceous Glands Ceruminous Glands Mammary Glands
- 55. 6-55 Sweat (sudoriferous) Glands Two kinds (described in Ch.5) 1. Merocrine glands is simple tubular gland – Most abundant, millions of them help cool the body by producing watery perspiration – Simple tubular gland, lined with stratified cuboidal epithelium – Myoepithelial cells: incorporated with secretory cells, respond to nervous stimuli thus squeezing the duct.
- 56. 6-56 Sweat (sudoriferous) Glands 2. Apocrine glands produce sweat containing fatty acids (thicker) – Opens to hair follicle rather than surface. – Respond to stress and sexual stimulation – No odor, unless trapped in clothing – bromhidrosis is body odor produced by bacterial action on fatty acids (body odor).
- 57. 6-57 Sweat (sudoriferous) Glands (FYI) • Protein-free filtrate of plasma and some waste products – K+, urea, lactic acid, ammonia, & NaCl – 500 ml of insensible perspiration/day, no noticeable wetness of skin. – sweating with visible wetness is diaphoresis
- 58. 6-58 Sebaceous Glands • Oily secretion called sebum that contains broken-down cells – lanolin in skin creams is sheep sebum • Flask-shaped gland with duct that opens into hair follicle • Sebum- Keeps skin and hair from becoming dry, brittle and cracked.
- 59. 6-59 Ceruminous Glands Found only in external ear canal Their secretion combines with sebum to produce earwax (cerumen). • Cerumen Function: 1. Waterproof auditory canal 2. keeps eardrum flexible 3. bitterness repel mites and other pests
- 60. 6-60 Mammary Glands • Breasts of both sexes rarely contain glands – secondary sexual characteristic of females • found only during lactation and pregnancy – modified apocrine sweat gland – thicker secretion released by ducts open on the nipple • Anatomy and Physiology is in greater detail in Chapter 28
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- 64. 6-64 Skin Cancer • Skin Cancer is one of the most common cancers most often on head and neck where exposure is greatest. • Easiest one to treat and has one of the highest survival rate when it is detected and treated early. • There are 3 types, named for their epidermal cells from which they originate and distinguished by their lesions.
- 65. 6-65 Skin Cancer • Induced by UV rays of the sun 1. basal cell carcinoma (least dangerous) • Most common • arises from stratum basale and invades dermis • Lesion starts as a small, shiny bump
- 66. 6-66 Skin Cancer 2. Squamous cell carcinoma • arises from keratinocytes in stratum spinosum • Lesion: raised, reddened, scaly, later an ulcer • Lesions appear can appear on: – Scalp, ears, lower lip, back of hand • metastasis to the lymph nodes can be lethal
- 67. 6-67 Skin Cancer 3. Malignant melanoma (most deadly) • arises from melanocytes of a preexisting mole • Metastasizes quickly if untreated • Greater incident in men then women • Result of oncogene BRAF in men, in women it does not trigger malignant melanoma but other cancers like breast and ovarian.
- 68. 6-68 American Cancer Society • “ABCD rule” • A = • B = • C = • D = Asymmetry, one side of lesion looks different from the other. Border irregularity, contour not uniform but wavy or scalloped Color, mixture of brown, black, tan, sometimes red and blue Diameter, greater than 6 mm
- 69. 6-69 Treatment • Surgery • Radiation therapy • Electrodesiccation (destroy by heat) • Cryosurgery (cold)
- 70. 6-70 Burns • Hot water, sunlight, radiation, electric shock or acids and bases • Death from fluid loss, infection and other toxic effects of Eschar. • Eschar: Burned, dead tissue
- 71. 6-71 Degree of Burns 1st Degree Burns • Involve only epidermis Characterized by: • reddness, slight edema, pain • Heals is a few days rarely scars • Most sunburns
- 72. 6-72 Degree of Burns 2nd Degree Burns • involves epidermis and part of dermis – Since it leaves some of the dermis intact, 1st and 2nd degree burns are considered PARTIAL – THICKNESS BURNS • Characterized by: – red, tan or white and is blistered, very painful – May heal from 2 weeks to several months, may scar – epidermis regenerates from epithelial cells in hair follicles and sweat glands – Scalds and some sunburns
- 73. 6-73 Degree of Burns 3rd Degree Burns (aka Full-thickness burn) • Epidermis, dermis and deeper tissues are destroyed. • Require skin graphs • If not taken care of, contracture (abnormal connective tissue fibrosis) results = severe disfigurement.
- 74. 6-74 Treatment 2 major conditions to treat: 1. fluid replacement – Patient can lose several liters of water, electrolytes and protein each day. – As fluid is lost from tissues, it is replaced by the blood stream, thus circulating blood volume declines. – Within a few hours a person can lose 75% of blood plama resulting in the principle cause of death from burns: • Circulatory shock and cardiac arrest – Intravenous fluids are given
- 75. 6-75 Treatment 2. Infection – Controlled by keeping the patient in an aseptic (sterile) environment – Administer antibiotics – Eschar is sterile in the first 24 hours but will quickly become infected and have a toxic effect on digestive, respiratory, and other systems – To control the infection Debridement is used. This is the removal of the eschar.
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- 77. 6-77 UVA, UVB and Sunscreens • UVA and UVB are improperly called “tanning rays” and “burning rays” • Both thought to initiate skin cancer • As sale of sunscreens has risen so has skin cancer – those who use have higher incidence of basal cell – chemical in sunscreen damage DNA and generate harmful free radicals • PABA, zinc oxide and titanium dioxide
Editor's Notes
- #5: Thick and thin based on thickness of the epidermis alone. THICK skin covers palms, soles and corresponding surfaces of the fingers and toes.
- #7: Barrier to water, prevents the body from absorbing water when swimming and bathing, as well as prevents water loss. O’Riain’s Sign (Shrivel Test): indicated when the fingers do not wrinkle after placed in warm water (30 minutes). NON wrinkling is due to denervation (sensibility) of the that particular nerve. (Return 90-120 days after injury). Vitamin D needed for bone development and maintenance. Extensive sense organ, can detect heat, cold, touch, texture, pressure, vibration and tissue injury. Location various areas. The dermis has nerve endings that are called Thermoreceptors that transmit back to the brain, then back to dermal blood vessels to vasoconstrict or vasodilate. Social function.
- #11: Melanocytes only in s. basale. Synthesize brown to black pigment melanin. Tactile receptors for sense of touch. Macrophages originate in the bone marrow and migrate to the epidermis of various sites. Guard against toxins,microbes, and other pathogens that penetrate into the skin.
- #15: Named for its histological appearance. Spinosum means shiny appearance.
- #21: Dead cell constantly flake off the skin surface, forming much of the house dust. Continuously being relaced. Thus the S. Corneum consists of compact dead cells. Flake off in specks called DANDER.
- #22: Dermatophagoides (der-MAT-oh-fah-GOY-deez)
- #24: Reticular layer contains dense irregular connective tissue. Stretching of the skin can tear this collagen fibers producing STRIAE or stretch marks.
- #28: Dermal Papillae: Epidermal and dermal areas interweave like corrugated cardboard. Produces resistance for non slip between the epidermis and dermis layers. Look at wrist and see delicate rectangule to rhomboid shapes. The dermal papillae for the raised areas between the furrows
- #33: The most significant factor in skin color is melanin. Produced by melanocytes but accumulates in the keratinocytes of the stratum basale and stratum spinosum.
- #40: Hard Keratin seen in hair and nails, more compact than soft keratin and is toughened by cross-linkage between keratin molecules. Soft Keratin seen skin, pliable stratum corneum. Difference is not the amount of hair but….
- #44: SEE FIGURE 6.8 in text
- #48: The question WHY DO HUMANS HAVE HAIR? Hair of the trunk and limbs is vestigial, with little known function. BODY HAIR kept our ancestors warm, but……. (go to slide). SCALP HAIR the brain receives a rich supply of warm blood and the scalp lack an insulating fat layer so heat is easily conducted through the bone of the skull and lost to surrounding air. GUARD HAIRS (aka vibrissae) EXPRESSION: not protect from sweat. Specialized frontalis muscles for this purpose.
- #51: Most mammals have claws, whereas primates have flat nail ( a distinguishing feature). Not only sensative but serve as strong keratinized “tools” for digging, grooming, picking food apart. CLUBBING
- #56: Apocrine sweat glands in groin, axillia. Their ducts lead to nearby hair follicles rather than opening directly onto skin. Produce their secretion like merocrine glands – exocytosis. hyperhidrosis :hands, prescriptions, botox injections and surgery 'endoscopic transthoracic sympathectomy' may cause increase sweating else where.
- #59: The sheen of well brushed hair is due to sebum, but we go through great lengths of trying to wash it out.
- #61: Mammary glands and breasts are often regarded as the one and the same. Breasts are present in both sexes, and in both sexes rarely contain mammary glands.
- #66: Skin Cancer is one of the most common cancers most often on head and neck where exposure is greatest. Easiest one to treat and has one of the highest survival rate when it is detected and treated early. 3 types named for the epidermal cells in which they originate. Basal Cell Carcinoma: common type, least dangerous bec. It seldom metastasizes. Squamous Cell Carcinoma: Usually appears on the scalp, ears, lower lip, or back of hand. Malignant Melanoma: (only accounts for 5% of all cases), metastasizes quickly,fatal if not treated. Men have a higher incident than women. Due to the BRAF oncogene in men. BRAF does not appear to trigger malignant melanoma, but it has been linked to some breast and ovarian cancers.
- #71: Leading cause of accidental deaths. DEATH results from fluid loss, infection and toxic effects called ESCHAR– burned, dead tissue. 1st degree are sunburns! 2nd degree aka Partial-thickness burns! Some sunburns and scalds. 3rd degree aka Full- thickness burns! Contracture (abnormal connective tissue fibrosis), severe disfigurement Fluid is lost from the tissues, more is transferred from the bloodstream. A person can lose up to 75% of blood plasma within a few hours leading to circulatory shock and cardiac arrest-Principal cause of death in burn patients. Infection is controlled by keeping the patient in an aseptic environment.