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Skin

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Skin

  1. 1. Integumentary system•Composed of the skin and a numberof skin derivatives (hair, nails, andglands).•Largest organ in the body•Accounts for 15 % of body’s weight
  2. 2. Integumentary systemFunctions:1. Protection a) Physical barrier b) Waterproofs c) Protects against sun’s ultraviolet light – pigment in the skin called melanin
  3. 3. Integumentary systemFunctions:2. Temperature regulation skin allows body to lose heat by evaporation, convection, conduction, and sweat3. Excretion excretes water, fatty substances and ions
  4. 4. Integumentary systemFunctions:4. Metabolism  Vitamin D5. Absorption if applied to the skin will absorb Vitamin A, E, and K, steroid hormones released by glands
  5. 5. Integumentary systemFunctions:6. Communication Stimuli are received by skin receptors which will communicate with the central nervous system
  6. 6. Integumentary system2 Layers of the SkinEpidermis - Top layer of stratified squamous epitheliumDermis - Layer underneath the epidermis made of connective tissue
  7. 7. Integumentary systemOther parts of the skin:Epidermal – dermal junction iswhere the epidermis and dermismeet.Hypodermis – is the layer of tissueunder the dermis.
  8. 8. Epidermal-dermaljunction
  9. 9. Integumentary systemTwo Layers of the Dermis:1. Papillary layer  Upper dermis  Has ridges that protrude up into the epidermis called the dermal papillae  It is composed of loose connective tissue
  10. 10. Integumentary systemFunctions of Dermal papillae:•Increased blood flow to epidermis•Increased surface area for dermisand epidermis to connect to eachother to hold it strongly together
  11. 11. Integumentary systemFunctions of Dermal papillae:•Contains sensory touch receptors•Keeps skin from tearing•Aids in gripping•Gives you finger prints
  12. 12. Dermal papillae = finger prints
  13. 13. Integumentary systemLayers of the dermis:1. Papillary layer2.Reticular layer Lower dermis Further keeps from tearing Contains deep pressure sensors Contains sweat glands, lymph vessels, smooth muscle, and hair follicles
  14. 14. Integumentary systemLayers of the dermis:1. Papillary layer2. Reticular layer Made of dense irregular connective tissue Has criss-cross collagen fibers that give it a strong elastic network This forms lines of cleavage or Langer’s Lines or Line of tension
  15. 15. Langer’s LinesNote: Incisionsparallel to theLanger’s Lineswill heal fasterand with lessscarring.
  16. 16. Integumentary systemHypodermisMade of adipose tissue to insulateand loose connective tissueFunctions to: 1.Conserve heat 2.Connects skin to layer below 3.Contains blood, lymph, base of hair follicles and sweat glands 4. Stores lipids and cushions the body
  17. 17. Integumentary systemHypodermisFunctions to: Hypodermis is 8% thicker in females than males
  18. 18. Integumentary systemHypodermis Also known as the subcutaneous tissue Where medical personal will give a subcutaneous injection because of the rich blood supply
  19. 19. Integumentary systemBlister – a separation between theepidermis and the dermisBurn - destruction of the differentlayers of the skin and the structureswithin the skin.The severity of the burn is dependentupon the depth of the damage.
  20. 20. Integumentary systemThree Classifications of burns:1. First degree or 1 is when there has been some damage to the epidermis
  21. 21. Integumentary systemThree Classifications of burns:2. Second degree or 2 is when the epidermis is completely destroyed and there is some damage to the dermis
  22. 22. Integumentary systemThree Classifications of burns:2. Second degreeNote: New epidermis will be regenerated from the cells surrounding the hair follicles. The hair follicles are lined with epidermal cells non-keratinized.
  23. 23. Integumentary systemThree Classifications of burns:3. Third degree or 3 is when the epidermis and dermis are completely destroyed and there isdamage tothehypodermis.Must have a skin graft to heal.
  24. 24. Integumentary systemLayers of the epidermis:composed of 4-5 layers depending onthe region of skin being consideredThose layers in descending order arethe stratum corneum, stratum lucidum,stratum granulosum, stratumspinosum, and stratum basale.
  25. 25. Layers of the epidermis
  26. 26. Integumentary systemLayers of the epidermis:1. Stratum basale also referred to as "basal cell layer” is the deepest layer Single layer ofcuboidal/columnar cells that undergoes rapid mitosis
  27. 27. Integumentary systemLayers of the epidermis:1. Stratum basale Cells migrate upward from here and begin to differentiate Also known as the stratum germinativum
  28. 28. Integumentary systemLayers of the epidermis:2. Stratum spinosum is several cell layers thick Carries out mitosis as well Some cells produce Keratin
  29. 29. Integumentary systemLayers of the epidermis:3. Stratum granulosum flat cells (squamous) Layer where keratinization begins cells overproduce the protein keratin and smother themselves cells in this layer are beginning to die
  30. 30. Integumentary systemLayers of the epidermis:4. Stratum lucidum found only in the thick skin of the palms of the hand and soles of the feet cells in this layer are dead three to four strata (layers) thick Helps protect against UV rays
  31. 31. Integumentary systemLayers of the epidermis:5. Stratum corneumoutermost layer of squamous cellscells filled with keratindead cells that have migrated up fromthe stratum granulosum is true protective layer of skin is 25 – 30 cell layers thick
  32. 32. Integumentary systemLayers of the epidermis:5. Stratum corneumthese dead cells slough off and arecontinuously replaced by new cellsthe sloughing off ofcells is known as desquamation
  33. 33. Integumentary systemLayers of the epidermis:5. Stratum corneumJust for your additional information:In the human forearm, for example,about 1300 cells/cm2/hr are shed andcommonly accumulate as house dustDesquamation – term in Latin forscaling a fish
  34. 34. Integumentary system MelaninIs a brown pigment found in the skin andhairprimary determinant of skin colorproduced by melanocytes in the stratumbasalethrough phagocytosis vesicles of melaninwill enter cells of stratum basale andspinosum
  35. 35. Integumentary system MelaninNote: The concentration ofmelanocytes in the skin of people isabout the same, but some don’tproduce as much melanin due togenetics.UV light willtrigger melanin production
  36. 36. Integumentary system MelaninSome individual animals and humanshave very little or no melanin in theirbodies, a condition known as albinism.There are a number of different typesof melanin giving different colors ofskin (ex. Eumelanin most common) andhair plus other pigments.
  37. 37. Integumentary system Skin CancersThere are three main types of skincancer:1. Malignant melanoma• cancer cells are found in the melanocytes• characterized by uncontrolled mitosis of melanocytes in the stratum basale
  38. 38. Integumentary system Skin CancersThere are three main types of skin cancer:1. Malignant melanoma usually occurs in adults is the rarest, but worst form of skin cancer has the highest death rate and is responsible for 75 percent of all deaths from skin cancer Usually in fair-skinned people
  39. 39. Integumentary system Skin CancersThere are three main types of skin cancer:1. Malignant melanoma2. Squamous cell carcinomauncontrolled mitosis of cell of thestratum spinosumNot as dangerous as melanoma, butmore dangerous than basal cellcarcinoma
  40. 40. Integumentary system Skin CancersThere are three main types of skin cancer:1. Malignant melanoma2. Squamous cell carcinoma95% cure rate when properly treatedmay appear as nodules, or as red,scaly patches of skin second most common skin cancer found in fair skinned individuals
  41. 41. Integumentary system Skin CancersThere are three main types of skin cancer:1. Malignant melanoma2. Squamous cell carcinoma3. Basal cell carcinomaUncontrolled mitosis of stratumbasale layer cellsusually appears as a small, fleshybump or nodule on the head, neck, orhands
  42. 42. Integumentary system Skin CancersThere are three main types of skin cancer:1. Malignant melanoma2. Squamous cell carcinoma3. Basal cell carcinomaeasily detected and has an excellentsuccessful treatment, when properlytreatedis the most common skin cancer, butmost treatablefound in fair-skinned individuals
  43. 43. Integumentary system Skin CancersMyth: Darker skinned people can’tget skin cancer.The darker the skin the less likely,but the more fatal.Usually melanoma the worst kind.Usually late diagnosis or diagnosedincorrectly
  44. 44. Integumentary system Skin CancersMyth: Darker skinned people can’t get skin cancer. almost always arise on the sole of thefoot, palms, fingers, toes, under thenails and mucosal surfaces like in themouth
  45. 45. Integumentary system Hair Follicle part of the skin that grows hair bypacking old cells togetherCover entire body except eyelids,palms, soles, and lips Attached to the hair follicle is asebaceous gland (oil gland)
  46. 46. Integumentary system Hair FollicleThe thicker density of hair, the moresebaceous glands are found•Also attached to the follicle is a tinybundle of muscle fiber called thearrector pili that cause hair to stand upand a goose bump.
  47. 47. Integumentary system Hair Follicle has two parts based on location: 1. Shaft – protrudes from the skin 2. Root – imbedded beneath the skin At the base of the root is the hair bulb
  48. 48. Hair shaft Hair root Hair bulb
  49. 49. Integumentary system Hair has no nervesComposed of hair structure and hairfollicleHas a protective function
  50. 50. Integumentary system Hair Strand has three layers:1. Medulla  center layer that is 2-3 cell layers thick Composed of soft keratin (less sulfur) and air
  51. 51. Integumentary system Hair Strand has three layers:2. Cortex  middle layer Composed of many cell layers Is hard keratin (contains more sulfur) Makes up most of hair strand contains melanin and maybe red hair pigments
  52. 52. Cortex
  53. 53. 2. CortexHair color:• melanin is produced and throughphagocytosis it is incorporated into cellsof cortex •the more melanin the darker the hair color •red hair also contains a red pigment, the more melanin the darker the red •gray hair lacks melanin at all
  54. 54. Integumentary system Hair Strand has three layers:3. Cuticle  outer most layer of hard keratin One cell layer thick, but cells overlap like shingles on the roof
  55. 55. Integumentary systemHair Follicle layers:1. Internal epithelial root sheath2. External epithelial root sheathTwo layers are covered by dermal root sheathHair bulb – expanded end of follicle
  56. 56. DermalRoot Inner sheathsheath Outer sheath
  57. 57. Integumentary system Hair FolliclePapilla – extends into the bulb and provides nutrients
  58. 58. Integumentary system Hair FollicleHair matrix Is at the base of the hair bulb Where cell mitosis/reproduction occurs Cells are undifferentiated (all look the same) Hair electrolysis damages the cell in the matrix cells don’t reproduce
  59. 59. Integumentary system Hair GrowthNot all hair grows at the same rateEyelashes/brows vs. hair on headHair grow and then stops
  60. 60. Integumentary system Hair GrowthThree stages of hair growth:1. Anagen a growth phase when hair is growing in length Eyelids – spend 30 days in this phase Head strand of hair spends 3 – 7 years in this phase 90% of head hair is in this phase
  61. 61. Integumentary system Hair GrowthThree stages of hair growth:1. Anagen2. Catagen Hair stops growing; transition phase Club hair or replacement hair is formed Head hair spend 2-3 weeks in this phase
  62. 62. Integumentary system Hair GrowthThree stages of hair growth:1. Anagen2. Catagen3. Telogen Resting phase – 10% of hair on head is in this phase head hair spends about 100 days in this phase, eyelids 9 months Hair falls out You lose about 100 hairs on your head per day
  63. 63. Integumentary system NailsFunctions: protections reinforce the finger/toe tips
  64. 64. Integumentary system Nails Parts of the NailoNail body – the part that is visibleoNail root – extends underneath theskinoNail matrix – part of nail root wherecells reproduce. Cells differentiate andfill with keratinoLunula – upper part of the nail matrix,is thicker and appears white
  65. 65. Integumentary system Nails Parts of the NailoNail bed – thick epithelial tissue thatthe nail rest onoFree edge – part that sticks out pastthe digitoCuticle – fold of skin on proximal end
  66. 66. Integumentary system NailsGrow constantly – no growth andresting phasesGrow at a rate of about 3 mm a month
  67. 67. Integumentary system GlandsTwo types based on what they secrete:1. Sweat – water and electrolytes, sweat2. Sebaceous - oil
  68. 68. Integumentary system GlandsTwo types of sweat glands:A. Merocrine  Found all over skin, heaviest in soles of feet and palms of hands  Secrete a clear liquid to surface of skin  Are a merocrine gland
  69. 69. Integumentary system GlandsTwo types of sweat glands:A. Merocrine  Regulates body temperature  Smaller and more numerous than apocrine sweat glands  Don’t secrete into hair follicle
  70. 70. Integumentary system GlandsTwo types of sweat glands:B. Apocrine glands  Found armpits, groin and nipples  Secrete a milky substance; odorous  Actually merocrine glands, but were once thought apocrine  Secrete into hair follicle  Found deeper in skin than merocrine
  71. 71. Integumentary system GlandsTwo types based on what they secrete:1. Sweat – water and electrolytes, sweat2. Sebaceous - oilSebaceous glandsSecrete an oily matter called sebuminto hair folliclesPore = opening of hair follicle to allowoil to lubricate the skinHolocrine glandsOverproduction of sebum = acne

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