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this powerpoint presentation is not originally mine and will be posted temporarily for the next 7 days and will be deleted from this account.



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    Skin Skin Presentation Transcript

    • Anatomy, Organization, Histology, Function of Human Skin and Diagnosis
    • The skin: is theinterface (surface)between human & environment
      is one of the largest organs in the body 
      Its surface area is of 1.8 - 2 m2 & makes up approximately 16% of our body weight ≈ 4kg
      is a window through which the physician can "see" the entire body
    • Normal Human Skin
    • Normal Skin Low Power with Labels
    • Skin normal histologyEpidermis:
      • thickness vary from 0.1mm in eyelids to 1mm in palm & sole
      • No blood vessels
      • Keratinocytes make 85% of it, other cells are melanocytes, langerhans cells, merkel cells
      • Transit time: is the time needed for cell maturation from basal layer to the surface, normally = 60 days
    • The skin is often referred to as the "integumentary
      system" composed of epithelial, mesenchymal, glandular
      and neurovascular components. 
      The integumentary system is synonymous with:
      1- The skin and its derivatives:
      sweat glands, nails, hair, sebaceous
      glands, arrector pili muscles.
      2- Mammary glands and
      3- Teeth
    • Functions of the Skin
      barrier to physical agents
      protects against mechanical injury
      prevents dehydration of body through fluid loss
      reduces the penetration of UV Radiation
      helps to regulate body temperature
      provides a surface for grip
      acts as a sensory organ
      acts as an outpost for immune surveillance
      plays a role in Vitamin D production
      has a cosmetic association
    • Functions of the skin
      1. Protection against:
      chemicals, particles horny layer
      UV radiation melanocytes
      Antigens, haptens langerhans cells
      Microbes langerhans cells
      2. Preservation of horny layer
      balanced internal
      3. Prevents loss of horny layer
      water, electrolytes, macromolecules
    • 4. Shock absorber, dermis & subcut. fat
      Strong, elastic, compliant
      5. Temprature blood vessels
      Regulation eccrine sweat glands
      6. Insulation subcutaneous fat
      7. Sensation specialized nerve endings
      8. Lubrication sebaceous glands
      9. Protection & prising nails
      10. Calorie reserve subcut. Fat
      11. Vitamine D synthesis keratinocytes
      12. Body odor & apocrine sweat glands
      pheromones: (chemicals for communication)
      13. psychological: skin, lip, hair & nails display
    • Based on the thickness of the epidermis,
      skin can also be classified as thick or thin:
      1) Thick skin
      - covers palms and soles,
      - has sweat glands, but lacks hair follicles, arrector pili muscles, and sebaceous glands
      2) Thin skin
      - covers most of the rest of the body
      - contains sweat glands & hair follicles, arrector pili muscles, and sebaceous glands.   
    • Layers of epidermis
      1. Basal layer ( stratum basalis):
      • deepest layer,
      • single layer of columnar layer
      • Keratinocytes have hemidesmosomes attached them to underlying lamina densa
      • In normal skin 30% of basal cells are preparing for division (growth fraction)
    • 2. Spinous (prickle) cell layer:
      • keratinocytes larger than basal layer
      • 7-9 layers of cells
      • Keratinocytes firmly attached by cytoplasmic process (desmosomes) & intercellular glycoprotein cement
      • Tonofilaments are small fibers running from cytoplasm to desmosomes
      • Tonofilaments packed into bundles called
      tonofibrils, more numerous in this layer
    • 3. Granular layer:
      2-3 layers
      Cells flatter than spinous layer,
      No nucleus
      No intracytoplasmic organelles
      More tonofibrils
      Contain irregular basophilic granules of keratohyalin.
    • 4.Stratum Luidum: palms & soles
      5. Stratum corneum: SC:
      • Made of layers of flattened dead cells
      (corneocytes), has no nuclei or
      cytoplasmic organelles.
      • Bricks-stuck together by intercellular lipids
      • Cytoplasm is picked with keratin filaments, embedded in a matrix, enclosed by an envlope derived from keratohyalin granules give corneocytes toughness allow skin to withstand chemical & mechanical insults
    • DEJ: Dermo-epidermal junction
      • the basement membrane lies at the interface between epidermis & dermis
      • plasma membrane of basal layer has hemidesmosomes .
      Composed of:
      • Lamina Lucida is electron lucent area lies below basal cell layer.
      • Lamina Densa
      Fine anchoring filaments cross lamina lucida & connect lamina densa to plasma membrane of basal cell layer.
      • Anchoring fibrils, dermal microfibril bundles & single small collagen extend from papillary dermis to deep part of lamina densa
      • Function of DEJ:
      Provide mechanical support
      Encouraging adhesion, growth, differentiation & migration of overlying basal cells
      Act as semipermeable filter that regulate transfer of nutrients & cells between dermis & epidermis
    • Dermis:
      1. Papillary layer
      2. Reticular layer
      Dermal Fibers:
      1. Collagen Fibers
      2. Elastic (Elastin) Fibers
    • Dermis:
      • Lies between epidermis & subcut. fat
      • Support epidermis structurally & nutritionally
      • Thickness greatest in palm & soles & least in eyelids & penis
      • Interdigitate with epidermis, upward projection of dermis is dermal papillae
      Rete ridges:
      • the downward ridges of epidermis is the rete ridges, which allow adhesion between dermis & epidermis as it increases the surface area between them
    • Cells & fibers of dermis
      Collagen fibers:
      make 70-80% of dermis dry weight
      Compose of thinner fibrils packed in bundles
      Made of 3 polypeptide chains
      Contain proline, hydroxyproline, glycin
      Its tensile strenth prevent tearing when skin is stretched
      Reticulin fibers:
      • are fine collagen fibers
      • seen in fetal skin & around blood vessels & appendages in adult skin
    • Elastic fibers:
      • 2% of dermis dry weight
      • elastin is made up of polypeptides rich in glycine, desmosine, valine
      • Have amorphous elastin core surrounded by elastic tissue micrifibrillar components
    • Ground substance of dermis
      • Composed of glycosaminoglycan (hyaluronic acid & dermatan sulphate) with smaller amount of heparan sulphate & chondroitin sulphate
      • Functions:
      • Ground substance binds water, allowing nutrients, hormones & waste products to pass through dermis
      • Acts as lubricants between fibers
      • Provides bulk act as shock absorber
    • Muscles
      • Smooth arrector pili muscle is vestigial in
      • 1- sebum expression
      2- goose pimples from cold,
      3- nipple erection
      • Raising of scrotum is by smooth dartos muscle
      • Striated fibers (platysma) & some of muscles of facial expression found in dermis
    • Blood vessels
      Regulate body temprature
      2 main horizontal plexus, superficial & deep
      Under sympathetic nervous control arteriovenous anastamoses can shunt blood to venous plexus reducing surface heat loss by convection
    • Nerves
      One million nerve fibers mostly in the face & extremities
      Cell bodies are in dorsal root ganglia
      Both mylinated & unmyelinated fibers exist
      Itch is follow stimulation of free nerve endings close to dermo-epidermal junction
    • Skin appendages (Adnexa): SHANS:
      1. Sweat glands
      2. Hair
      3. Arrector pilli muscle
      4. Nails
      5. Sebaceous glands
    • Skin appendages (Adnexa): SHANS:
      Hair: is human plumage
      • Hair follicle form before nine week of fetal life when hair germ grows obliquely down into dermis.
      It includes the following parts:
      • Infandibulum: from surface to entrance of sebaceous g.
      • Asthmus: between entrance of seb. g to attachment of arrector pili muscle
      • Hair Matrix: is the inferior portion including the hair bulb
      • Free of hair areas: Lip, glans penis, labia minora, palms, soles
      • Hair cycle: anagen, catagen & telogen
      • Typesof hair: 1- Lanugo hair
      2- Vellus hair 3- Terminal hair
    • Nails
      Hard keratin of nail plate formed in nail matrix which lies in an invagination of epidermis on back of terminal phalanx of digits toes
      It provide strength & protection for terminal phalanx & allow handling of fine objects
      Finger nail growth is 0.5-1.2 mm per week
      Slower in toe nails
      Faster growth in summer
    • Skin Emberiology:
      Origins of the Integumentary System: (The Skin)
      The skin basically consists of two layers that are derived from two germ layers: ectoderm and mesoderm.
      The epidermis is from surface ectoderm.
      The dermis is derived from mesoderm.
      Mesenchyme: is the embryonic meshwork of connective tissue (CT).
    • Hair: A hair follicle develops as a proliferation of the epidermal stratum germinativum and extends into the underlying mesenchyme.
      Nails:develop from thickened areas of epidermis at the tips of each digit called nail fields.
      Later these nail fields migrate onto the dorsal surface surrounded laterally and proximally by folds of epidermis called nail folds
    • Both the sebaceous glands and sweat glands (+ mammary glands) are derived from the epidermis and grow downwards into the dermis.
      The majority of sebaceous glands
      originate as buds from developing
      hair follicle root sheath.
      Sebaceous glands in the glans penis and labia minora (independent of hair follicles) develop similarly, but as buds from the epidermis.    
    • Sweat glands:
      - Eccrine sweat glands
      located throughout the body originate as downgrowths from the epidermis into the underlying mesenchyme.
      As a result, these eccrine ducts open onto the surface of the skin.
      - Apocrine sweat glands
      are located in the axilla, pubic region, perineal region, and areolae of the nipples.
      originate instead as downgrowths from the epidermal stratum germinativum (which also gives rise to hair follicles).
      As a result, these apocrine ducts open into the upper part of hair follicles above sebaceous gland openings.
    • The Physiology of Skin
      The skin is a metabolically active organ with vital functions such as protection and homeostasis. 
      When discussing the physiology of the skin and its derivatives, the following topics are important:
    • Keratinocyte Maturation:
      The aging of basal cells into the corneocytes (dead cells) is crucial.
      The stratum corneum is important in preventing all manner of agents from entering the skin, including micro-organisms, water and particulate matter.
      It's the epidermis that also prevents loss of vital body fluids.
      The dividing basal cell on average replicates every 200 to 400 hours, and the resulting cell takes 14 days to differentiate and 14 days to be shed.
    • Hair Growth
      Unlike most mammals, humans are considered "nude“ رووت ; thus, hair does not play the same vital role of heat conservation.
      However, the hair on the scalp does protect us from UV radiation and minor injury.
      Today, hair is of cosmetic value.
      Hair growth is cyclical and has three phases.
      The 3 phases are:
    • 1) Anagen is the growing phase.
      Its duration depends on the location of the hair.
      For eyebrow hair, this phase only lasts 4 months, but for scalp hair it lasts from 3-7 years.
      At any moment, 80-90% of scalp hairs are in anagen; daily, approximately 50-100 scalp follicles switch to the catagen phase.
      2) Catagen is the resting phase and lasts 3-4 weeks.
      There is a stop to hair protein synthesis as the hair follicle retreats towards the surface.
      At any moment, less than 1% of hairs are in the catagen phase.
      3) Telogen is the shedding phase and
      is characterized by hairs with a short club root.
      Daily, approximately 50-100 scalp hairs are shed.
      At any moment, 10-20% of scalp hairs are in telogen.
    • Dermatological General & Specific Terms:
      Dermatologists have some universal terms that are used when describing skin conditions:
      Eruption (or rash):
      2 Types of Skin Lesions:
      1- Primary Skin Lesions
      2- Secondary Skin Lesions
    • 1- Primary Lesions: are the first to appear and are due to the disease or abnormal state. 
      Must be distinguished from secondary or induced lesions
      Wheal, Erythema, abscess, Angiodema, Tumor, Petechiae, Purpura, Ecchymosis, Haematoma, Burrow, Comedo, Telangiectasia & Poikiloderma
    • Macule:small,flat, nonpalpable circumscribed area of change in color or texture of the skin.
      are < 0.5 cm in size,
      more than 0.5 called patches
      1. Macules (individual) may be the result of
      (A) hyperpigmentation: e.g. brown as in lentigos)
      (B) depigmentation (e.g. vitiligo), 
      (C) vascular dilation (e.g. erythema)
      2. Multiple well-defined macules of
      various shapes and sizes. 
      In this case, the macules blanch upon pressure(diascopy) and thus are due to inflammatory vasodilation.
    • Papule: small solid elevation of skin
      < 5 mm in diameter.
      Projects above the plane of the surrounding skin
      Flat-topped (in lichen planus) or
      Dome shaped (in xanthomas) or
      Spicular (if related to hair follicles)
    • Nodule:palpable, solid, round, or ellipsoidal lesion
      Its depth of involvement and/or palpability differentiate it from a papule rather than its diameter
      Larger than papules: > 5 mm diameter (in both depth & width)
      Any layer of the skin
      Edematous or solid.
      5 types of nodules: epidermal, epidermal-dermal, dermal,  dermal-subdermal, and subcutaneous
    • Vesicle (blister):circumscribed, elevated lesion
      is < 5 mm in diameter containing serous (clear) fluid.
      A vesicle/bulla is the technical term for blisters
      Vesicle walls can be so thin that the contained serum, lymph, blood, or extracellular fluid is easily seen.
      Fluid can be accumulated within or below the epidermis
      Pustule: Vesicle contains pus
      Bulla: Vesicle more than 0.5 cm
    • Bulla: A vesicle with a diameter > 5 mm. 
      2. Epidermal
      Subepidermal vesicles
    • Pustule:superficial, elevated lesion
      that contains pus (pus in a blister).
      • may vary in size and shape.
      • The color may appear white, yellow, or greenish-yellow depending on the color of the pus.
      • Pus is composed of leukocytes with or without cellular debris
      • may also contain bacteria or may be sterile
      1. A pustule is basically a papule containing pus
      2. Superficial, subcorneal pustules ( e.g. pustularpsoriasis) `
    • Cyst: an epithelial lined cavity containing liquid or semisolid material (fluid, cells, and cell products)
      • A spherical or oval papule or nodule may be a cyst if, when palpated, is resilient (feels like an eyeball).
    • Plaque: palpable, plateau-like elevation of skin, usually more than 0.5 cm in diameter without substantial growth
      Often formed by a convergence of papules, as in psoriasis. 1. Plaques occupy a relatively large surface area in comparison with its height above the skin
    • Wheal: elevated, transitory, compressible papule or plaque produced by dermal edema
      The papule or plaque is usually rounded or flat-toped, and evanescent, disappearing within hours.
      The borders of a wheal are sharp, but not stable and can move from involved to adjacent uninvolved areas over hours.
      The epidermisis not affected.
      can be pale red or white (especially in the center) if edema is sufficient to compress superficial vessels.
    • Erythema: is redness caused by vascular dilatation
    • Abscess: localized collection of puss more than 1 cm in diameter
    • Angiodema: is diffuse swelling caused by subcutaneous oedema
    • Tumor: is an enlargement of the tissue by normal or pathological material or cell greater than 1 cm in diameter
    • Petechiae: pinhead sized macules of blood
    • Purpura: larger macule or papule of blood
    • Ecchymosis: a collection of blood greater than 1 cm in size outside the vascular tree (extravasation of blood), in the skin and within tissue
    • Haematoma: is swelling from gross bleeding
    • Burrow: is linear or curvilinearpapule as in scabies
    • Comedo: is a plug of greasy keratin wedged in a dilated pilosebaceous orifice
    • 2- Secondary Lesions
      From the natural evolution of primary lesions
      a. From Eroded area left by bursting vesicle or
      b. From the patient's manipulation of the primary lesion (scratching):-  
      ScaleUlcerCrustErosionExcoriationLichenificationAtrophyScar, fissure, Sinus, Keratosis, Striae & Pigmentation
    • Scale: is a flake
      is accumulation or abnormal shedding arising from horny layer keratin: (SC)
      may be primary or secondary.
      usually indicates inflammatory change and thickening of the epidermis
    • Erosion, Fissure (fish Your), and Ulcer
    • Erosion: moist, circumscribed, usually depressed lesion due to loss of all or part of the epidermis,
      heals without scardue to:
      1. Herpes viruses (vesicles)
      2. Pemphigus (bullae)
      3. Toxic epidermal necrosis :TEN
    • Ulcer: a "hole in the skin"
      circumscribed area of skin loss extending through the epidermis and at papillary dermis
      heals with scarring
      results from the impairment of
      vascular and nutrient supply to the skin
    • Crust: look like scale but composed of dried serum, blood, or pus on the surface of skin.
      • May be thin, delicate, and friable or
      thick and adherent.
      - Yellow, if from serum;
      - Green or yellow-green if from pus; or
      - Brown or dark red if formed from blood.
      • Characteristic of pyogenic infections
      • Crusts that occur as honey-coloured, delicate, glistening particulates are typical of - Impetigo.
    • Excoriation:
      Epidermallinear or punctate
      superficial excavations (ulcer or erosion)
      caused by scratching, rubbing, or picking.
    • Lichenification: chronic thickening of the skin along with increased skin markings.
      Results from scratching or rubbing
    • Atrophy: Thinning of skin caused by diminution of epidermis, dermis or subcut. tissue
      • paper-thin, wrinkled skin with easily visible vessels.
      • Results from loss of epidermis, dermis or both.
      • Seen in:
      - aged,
      - some burns,
      - long-term use of
      highly potent topical
      corticosteroids (Cs).
    • Scar:is a pattern of healing where normal structures replaced by fibrousCT at a site of injury to the dermis.
      1- HypertrophicScar
      2- AtrophicScar
      3- Sclerotic or hard Scar due to collagen
    • 1- Hypertrophic or
      2- atrophic scar. 3-Sclerotic or hard Scar
    • Fissure: is a skin slit
      Heel fissure
    • Sinus: is a cavity or channel permits escape of fluid or pus
    • Keratosis:
      is a horn like thickening of stratum corneum(SC)
    • Striae: is a streak like linear atrophic pink purple or white lesions (or called stretch marks).
    • Pigmentation:more or less darker than surrounding skin
    • Thank you
      Thank You