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Anatomy and Physiology of the Hair           and Skin
Learning Objectives1.)   Name the layers of the epidermis.2.)   Name appendages within the dermis.3.)   List the major fun...
Integumentary systemThe skin and its accessory organs  Sebaceous glands  Sudoriferous glands  Sensory perceptors  Hai...
Pilosebaceous unitThe hair follicle and its appendages  Internal and external root sheaths  Hair shaft  Dermal papilla...
Overall Look at SkinBody’s largest organ  Up to 20 square feet on the average personMade of epithelial tissue and conne...
Epidermis       “Horny Zone”     Cells divide in the lowestStratum Corneum         layer                        Migrate...
Stratum CorneumA.K.A – “horny layer”Outermost layer of dead skin cellsConstantly sheddingMostly bound by sebum  Sebum...
Stratum LucidumBelow stratum corneumCells allow light to pass through themOnly present in palms of hands and soles of f...
Stratum GranulosumAKA – “granular layer”Cells are livingAs cells are pushed upward, lose nuclei and dieGives skin opaq...
Stratum SpinosumAKA – “Prickle cell layer”Made of living cellsAttached to each other by prickly shaped fibers
Stratum GerminativumLowest layer of epidermisMitosis (cell division) occurs hereCells migrate up, replacing dead skin c...
Stratum GerminativumContains melanocytes  UV rays react with amino acid tyrosine found in melanocytes to   produce melan...
Skin ColorSkin color depends on melaninPeople have same number of melanocytes  Dark skin – melanocytes are more active,...
DermisLiving layer or “true skin”Made of dense connective tissueDivided into two layers   Papillary layer   Reticular...
Papillary layerMade of fibers called papillae   Connects epidermis and dermisSuperficial capillaries looped around papi...
Reticular LayerThickest layer of skinDense bundles of collagen fibers Fibers are denser closer to papillary layer and t...
Blood SupplyArteries and veins circulate into the dermis and branch into smaller capillaries at the hair follicles, the h...
Lymph SupplyLymph glands produce lymph  Contains waste products, salts, nitrogenous wastes  Carried through vessels to ...
Sudoriferous GlandsSweat glandsFound deep in dermis  Tubular ducts going to pores in epidermisTwo kinds of sweat gland...
Types of Sudoriferous GlandsApocrine   Found in genital area and armpits (axillae)   Create body odor   Believed to ex...
Sebaceous GlandsFound all over skinMost often appendages to the hair follicles and open into the shafts of the follicles...
Nerve EndingsCarry impulses to the brainFound at various levels, various shapes, depending on purposeMost superficial a...
Hair AKA – pilosebaceous unit Found all over body except palms of hands and soles of feet   Most is invisible to naked ...
Subcutaneous LayerLocated at base of dermisLayer of fatty tissueAKA – subcutis; adipose tissueSeparates dermis from mu...
Structure of Hair – Follicular Canal and      SheathsFollicular canal – depression in the skin that houses the hairExter...
Hair ShaftLined with epidermal tissue extends through dermis into subcutaneous tissueEpidermal cells produce follicle an...
Internal Root SheathInnermost layer of the follicleCan sometimes see on tweezed hair   Looks like clump of    petroleum...
Dermal Papilla and PapillaeDermal papilla – located at base of bulb   Layer of dermal tissue that attaches itself to the...
Arrector Pili MuscleAttaches to the underside of the hair at the dermal papilla and the hair shaftResponsible for liftin...
Sebaceous GlandAttached to hair follicle and opens into shaftSecretes sebum   Lubricates hair to prevent dryness and br...
Layers of the Hair3 layers compose the hair:  1.) Cuticle  2.) Cortex  3.) Medulla
CuticleOutermost layerPurpose: protect inner layers of the hair
CortexBelow the cuticleContains pigment that gives hair its colorGives hair its strength and elasticity
MedullaInnermost layerAKA – pith or marrowFine hair lacks medullaCan be found in all wavy hair  General rule: curlier...
3 Types of Hair1.) Lanugo2.) Vellus3.) Terminal
LanugoAKA – fetal hairSoft, downy hair on fetuses in utero and infants at birth, covering bodies and scalpMay contain p...
Vellus – “peach fuzz”Confused with lanugo; difference is vellus is present through adulthoodFine, short, often no pigmen...
TerminalLonger, coarser hair that covers scalp, arms, legs, groin area, axillae, and on faces, chests, and backs of menH...
Stages of Hair Growth1.) Growing - Anagen2.) Transitional - Catagen3.) Resting – Telogen**ACT
Anagen: The Growing PhaseHair follicle at its deepestHair matrix active, surrounding the dermal papillaCan be affected ...
Catagen: The Transitional PhaseFollicle separates from dermal papilla and shrinks to 1/3 of sizeThin cord of epidermal t...
Telogen: The Resting StageFollicle is 1/3 of original sizeBase looks like clubBulb is usually whiteDermal papilla is s...
Hair GrowthIncomplete scienceThings we know:  Hair grows faster in the summer  Good health improve hair growth  Young...
Functions of the SkinLargest sensory organMultiple functions:  Protection  Heat regulation  Excretion – discharging w...
ProtectionSkin protects the body against the environment and invasion of bacteria.Skin is usually NOT sterile and is cov...
Acid MantlepH of 5 to 5.6Created by the combined activity of sweat and sebaceous  glands  Perspiration is acidic and ac...
Protection continuedWhen organism does invade skin, reactions (inflammation, swelling, welts) occur.Leucocytes are relea...
Protection continuedHorny layer acts as barrierSkin is waterproof (thanks in part to sebum)Sebum prevents drying and cr...
Protection continuedStratum germinativum protects by containing melanocytes which  produce melanin  Melanin – the body’s...
Protection continuedAdipose tissue – cushions the body from falls, protects  against minor trauma, and provides source of...
Protection by Lymphatic SystemLymphatic fluid and lymphocytes are produced in lymph  nodes.  Lymphocytes transported thr...
Heat RegulationHealthy body temperature of 98°F or 37°CSkin helps body to adjust and maintain a safe temperature  Evapo...
Heat Regulation – Evaporation andPerspirationEvaporation of perspiration produces cooling (AKA  thermoregulation).
Heat Regulation - RadiationRadiation from constriction or dilation of capillaries affect  body temperature.  Dilation (e...
Heat Regulation - InsulationArrector pili muscle contracts, lifts hair, trapping a layer of insulating air on skin’s surf...
Secretion and ExcretionSebaceous glands – secrete sebum, skin’s natural lubricantSudoriferous glands – excrete salt, ure...
SensationExperience heat, cold, pain, pressureDamage to nerves can leave the skin numb, once tissue has  healed.
Absorption and PenetrationSkin can absorb oil- and fat-based substancesPharmaceutical creams and lotions penetrate the d...
Absorption and PenetrationCosmoceuticals contain NO drugs or medications but could  cause drug reactions.  May have deep...
1.) What are the three main layers of theskin?Epidermis, dermis, and subcutis or subcutaneous layer.
2.) Into which two zones is the epidermisdivided?Horny zone and germinal zone.
3.) Name two layers of the epidermis.Stratum corneum,stratum lucidum,stratum granulosum,stratum spinosum,stratum germinati...
4.) In which layer are melanocytes found?Stratum germinativum
5.) What are the two layers of the dermis?Papillary layer and reticular layer
6.) What is a sudorific gland?A sweat gland, or gland that excretes salt, urea, and other waste  material.
8.) Where is the hair matrix?In the hair follicle bulb
9.) What are the three stages of hairgrowth?Anagen, catagen, and telogen
10.) Name at least five functions of theskin.Protection, heat regulation, excretion, secretion, absorption,  sensation, sy...
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D anatomy and physiology of the hair and skin

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D anatomy and physiology of the hair and skin

  1. 1. Anatomy and Physiology of the Hair and Skin
  2. 2. Learning Objectives1.) Name the layers of the epidermis.2.) Name appendages within the dermis.3.) List the major functions of the skin.4.) Name components of the pilosebaceous unit.5.) Name the three stages of hair growth.
  3. 3. Integumentary systemThe skin and its accessory organs Sebaceous glands Sudoriferous glands Sensory perceptors Hair Nails
  4. 4. Pilosebaceous unitThe hair follicle and its appendages Internal and external root sheaths Hair shaft Dermal papilla Sebaceous gland Arrector pili muscle
  5. 5. Overall Look at SkinBody’s largest organ Up to 20 square feet on the average personMade of epithelial tissue and connective tissue Epithelial – forms thin protective layer Connective – binds, protects, cushions, & supports3 main layers Epidermis Dermis Subcutis or subcutaneous layer
  6. 6. Epidermis “Horny Zone” Cells divide in the lowestStratum Corneum layer Migrate up to replace deadStratum Lucidum cells that have been shedStratum Granulosum As they move up, they are “Germinal Zone” filled with keratin to protectStratum Spinosum against invasion (keratinization)Stratum Germinativum
  7. 7. Stratum CorneumA.K.A – “horny layer”Outermost layer of dead skin cellsConstantly sheddingMostly bound by sebum Sebum – fatty or oily secretion of sebaceous gland; serves as lubrication
  8. 8. Stratum LucidumBelow stratum corneumCells allow light to pass through themOnly present in palms of hands and soles of feet, where epidermis is thickestPurpose unknown
  9. 9. Stratum GranulosumAKA – “granular layer”Cells are livingAs cells are pushed upward, lose nuclei and dieGives skin opaque appearanceVaries in thickness Persistent friction and pressure cause areas to thicken for protection and form calluses
  10. 10. Stratum SpinosumAKA – “Prickle cell layer”Made of living cellsAttached to each other by prickly shaped fibers
  11. 11. Stratum GerminativumLowest layer of epidermisMitosis (cell division) occurs hereCells migrate up, replacing dead skin cells that have been shedDesquamation (exfoliating dead skin cells) takes about 28 daysStratum mucosum – single cell layer
  12. 12. Stratum GerminativumContains melanocytes UV rays react with amino acid tyrosine found in melanocytes to produce melaninMelanin Dark pigment gives skin color and protects dermis from UV radiation and sun damage
  13. 13. Skin ColorSkin color depends on melaninPeople have same number of melanocytes Dark skin – melanocytes are more active, producing more melanin
  14. 14. DermisLiving layer or “true skin”Made of dense connective tissueDivided into two layers  Papillary layer  Reticular layer
  15. 15. Papillary layerMade of fibers called papillae  Connects epidermis and dermisSuperficial capillaries looped around papillaeNerve endings sensitive to touchThis layer forms the connective tissue sheath around hair follicles.
  16. 16. Reticular LayerThickest layer of skinDense bundles of collagen fibers Fibers are denser closer to papillary layer and thin as they near the fatty subcutaneous tissueAppendages Arrector pili muscles Blood vessels Fat cells Hair follicles Lymph vessels Nerve endings Sebaceous glands Sudoriferous glands
  17. 17. Blood SupplyArteries and veins circulate into the dermis and branch into smaller capillaries at the hair follicles, the hair papillae, and glandsTransports oxygen-rich blood and nutrients essential for: Growth Reproduction Tissue repair
  18. 18. Lymph SupplyLymph glands produce lymph Contains waste products, salts, nitrogenous wastes Carried through vessels to lymph nodes and fluid is filtered for excretion
  19. 19. Sudoriferous GlandsSweat glandsFound deep in dermis Tubular ducts going to pores in epidermisTwo kinds of sweat glands:  Apocrine  Eccrine
  20. 20. Types of Sudoriferous GlandsApocrine  Found in genital area and armpits (axillae)  Create body odor  Believed to excrete pheromonesEccrine  Found all over body  Increased numbers on forehead, palms, soles of feet
  21. 21. Sebaceous GlandsFound all over skinMost often appendages to the hair follicles and open into the shafts of the folliclesProduce waxy, oily substance called sebum which lubricates skin  Most active during puberty
  22. 22. Nerve EndingsCarry impulses to the brainFound at various levels, various shapes, depending on purposeMost superficial are responsible for touchClose to surface is pain receptor  Below that are receptors for heat and coldDeeper in dermis are pressure receptors
  23. 23. Hair AKA – pilosebaceous unit Found all over body except palms of hands and soles of feet  Most is invisible to naked eyeDenser on head and limbs, after puberty in groin area and axillae (armpits) Hair growth influenced by hormones and genetic inheritance
  24. 24. Subcutaneous LayerLocated at base of dermisLayer of fatty tissueAKA – subcutis; adipose tissueSeparates dermis from muscles and helps skin to move over themContains arteries, veins, lymph, nerve endings, fat cells
  25. 25. Structure of Hair – Follicular Canal and SheathsFollicular canal – depression in the skin that houses the hairExternal root sheath – inner side of canal
  26. 26. Hair ShaftLined with epidermal tissue extends through dermis into subcutaneous tissueEpidermal cells produce follicle and hair matrixBase of follicle widens into hair follicle bulb Bulb – where hair grows; contains hair matrix which is where cell division occurs Hair matrix produces the hair and external and internal root sheath
  27. 27. Internal Root SheathInnermost layer of the follicleCan sometimes see on tweezed hair  Looks like clump of petroleum jellyProtects hair up as far as sebaceous gland
  28. 28. Dermal Papilla and PapillaeDermal papilla – located at base of bulb  Layer of dermal tissue that attaches itself to the epidermis with papillaePapillae contain blood vessels – needed for nutrients and hormones for growth
  29. 29. Arrector Pili MuscleAttaches to the underside of the hair at the dermal papilla and the hair shaftResponsible for lifting the hair, trapping a layer of air on the skin’s surface  assisting in heat regulation  fear and cold stimulate contraction  causes “goose bumps”
  30. 30. Sebaceous GlandAttached to hair follicle and opens into shaftSecretes sebum  Lubricates hair to prevent dryness and breakage  Lubricates epidermis to prevent dryness and to prevent bacteria and germs from entering
  31. 31. Layers of the Hair3 layers compose the hair: 1.) Cuticle 2.) Cortex 3.) Medulla
  32. 32. CuticleOutermost layerPurpose: protect inner layers of the hair
  33. 33. CortexBelow the cuticleContains pigment that gives hair its colorGives hair its strength and elasticity
  34. 34. MedullaInnermost layerAKA – pith or marrowFine hair lacks medullaCan be found in all wavy hair General rule: curlier the hair, the stronger the medulla
  35. 35. 3 Types of Hair1.) Lanugo2.) Vellus3.) Terminal
  36. 36. LanugoAKA – fetal hairSoft, downy hair on fetuses in utero and infants at birth, covering bodies and scalpMay contain pigment, light or darkSheds a few weeks after birthPermanent hair begins to grow in
  37. 37. Vellus – “peach fuzz”Confused with lanugo; difference is vellus is present through adulthoodFine, short, often no pigment or medullaWomen believed to have 55% more vellus hair than men
  38. 38. TerminalLonger, coarser hair that covers scalp, arms, legs, groin area, axillae, and on faces, chests, and backs of menHair follicles can produce vellus or terminal hair.Affected by: Age Genetics Health Hormonal changes of puberty, pregnancy, and menopause
  39. 39. Stages of Hair Growth1.) Growing - Anagen2.) Transitional - Catagen3.) Resting – Telogen**ACT
  40. 40. Anagen: The Growing PhaseHair follicle at its deepestHair matrix active, surrounding the dermal papillaCan be affected by health of the individualOnce hair reaches full length it can remain there, depending on location, for varying amounts of time.
  41. 41. Catagen: The Transitional PhaseFollicle separates from dermal papilla and shrinks to 1/3 of sizeThin cord of epidermal tissue attaching follicle to dermal papilla retracts upward with the dermal papillaShortest hair growth stage
  42. 42. Telogen: The Resting StageFollicle is 1/3 of original sizeBase looks like clubBulb is usually whiteDermal papilla is separated from hair follicle and attached by thin cord of epidermal cells; will be released by end of phase
  43. 43. Hair GrowthIncomplete scienceThings we know: Hair grows faster in the summer Good health improve hair growth Young people experience more hair growth Increase in number of telogen hairs during illness, after childbirth, and when experiencing stress.
  44. 44. Functions of the SkinLargest sensory organMultiple functions: Protection Heat regulation Excretion – discharging waste material Secretion – producing and discharging substances from glands Absorption – uptake of one substance into another Sensation Synthesis of Vitamin DHair plays important role in these functions.
  45. 45. ProtectionSkin protects the body against the environment and invasion of bacteria.Skin is usually NOT sterile and is covered by bacteria  Noninvading and nonpathogenic bacteriaBuilt-in protective aid, ACID MANTLE
  46. 46. Acid MantlepH of 5 to 5.6Created by the combined activity of sweat and sebaceous glands Perspiration is acidic and acts as bactericide (inhibits growth of bacteria) NOT TRUE of areas of higher perspiration (groin and axillae), skin is softer and less acidity in excessive perspiration
  47. 47. Protection continuedWhen organism does invade skin, reactions (inflammation, swelling, welts) occur.Leucocytes are released and destroy the invading organism.Reactions help to prevent spread of infection to surrounding tissue.
  48. 48. Protection continuedHorny layer acts as barrierSkin is waterproof (thanks in part to sebum)Sebum prevents drying and cracking → prevents bacteria and germs from enteringWhen intact, skin prevents harmful fluids from entering and prevents water, blood, and lymph from leaving.
  49. 49. Protection continuedStratum germinativum protects by containing melanocytes which produce melanin Melanin – the body’s own sunscreen which protects from harmful UV radiationDark skin get better protection, few incidences of skin cancer
  50. 50. Protection continuedAdipose tissue – cushions the body from falls, protects against minor trauma, and provides source of energy
  51. 51. Protection by Lymphatic SystemLymphatic fluid and lymphocytes are produced in lymph nodes. Lymphocytes transported through lymph vessels Engulf bacteria Carried back to lymph nodes Filtered and drained of waste products
  52. 52. Heat RegulationHealthy body temperature of 98°F or 37°CSkin helps body to adjust and maintain a safe temperature Evaporation Perspiration Radiation Insulation
  53. 53. Heat Regulation – Evaporation andPerspirationEvaporation of perspiration produces cooling (AKA thermoregulation).
  54. 54. Heat Regulation - RadiationRadiation from constriction or dilation of capillaries affect body temperature. Dilation (expansion) causes surface heat of body to be reduced through radiation. Causes flushed appearance. Constriction (contraction) slows blood flow, preserving heat. Gives skin bluish tint.
  55. 55. Heat Regulation - InsulationArrector pili muscle contracts, lifts hair, trapping a layer of insulating air on skin’s surface. (Air is the best insulator!)Sebum lubricates hair, preventing it from breaking; allows hair to do its job.Adipose tissue acts as effective insulator, keeping body warm.
  56. 56. Secretion and ExcretionSebaceous glands – secrete sebum, skin’s natural lubricantSudoriferous glands – excrete salt, urea, and other waste material during perspiration.
  57. 57. SensationExperience heat, cold, pain, pressureDamage to nerves can leave the skin numb, once tissue has healed.
  58. 58. Absorption and PenetrationSkin can absorb oil- and fat-based substancesPharmaceutical creams and lotions penetrate the dermis and absorb into the blood supply Require medical guidance and physicians’ prescriptions to be obtained
  59. 59. Absorption and PenetrationCosmoceuticals contain NO drugs or medications but could cause drug reactions. May have deeper absorption qualities than over-the-counter cosmetics. Obtained from and require professional guidance of dermatologist, plastic surgeon, or skin-care professional.
  60. 60. 1.) What are the three main layers of theskin?Epidermis, dermis, and subcutis or subcutaneous layer.
  61. 61. 2.) Into which two zones is the epidermisdivided?Horny zone and germinal zone.
  62. 62. 3.) Name two layers of the epidermis.Stratum corneum,stratum lucidum,stratum granulosum,stratum spinosum,stratum germinativum.
  63. 63. 4.) In which layer are melanocytes found?Stratum germinativum
  64. 64. 5.) What are the two layers of the dermis?Papillary layer and reticular layer
  65. 65. 6.) What is a sudorific gland?A sweat gland, or gland that excretes salt, urea, and other waste material.
  66. 66. 8.) Where is the hair matrix?In the hair follicle bulb
  67. 67. 9.) What are the three stages of hairgrowth?Anagen, catagen, and telogen
  68. 68. 10.) Name at least five functions of theskin.Protection, heat regulation, excretion, secretion, absorption, sensation, synthesis of Vitamin D.

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