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Published byBarrie Harmon Modified over 9 years ago
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Skin 16% Body weight 1.2 – 2.3m² 1- Epidermis ( st.sq.ep ): Ectoderm 2- Dermis (C.T.) : Mesoderm A-papillary layer B-reticular layer Dermal papillae Epidermal ridge Hypoderm (L.C.T., Adipose =superficial fascia )
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Types of epidermal papilla
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Skin functions 1- live out of water (evaporation) 2- Receptor 3-Termal regulation (adipose tissue, vessels,sweet glands ) 4-Melanin (UV) 5-Metabolic function: Vitamin D3 6-Barrier (micro organisms, pathogenes,..) 7-Pheromones(apocrine glands) Elasticity (edema, pregnancy,.. ) Dermatoglyphics
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Type of fingerprint
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Types of skins 1-Hairy skin (thin skin) 2-Non hairy skin (Thick skin,glabrous)
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400-600 75-150
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The cell layers of epidermis 1-Stratum Basale 2-Stratum spinosum 3-Stratum Granulosum 4-Stratum Lucidum 5-Stratum Corneum 6-Stratum Disjunctivum
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1-Stratum Basale Simple cuboidal or columnar,basophile,Basal lamina Desmosome & hemidesmosome Mitosis, turnover (15 – 30 days,age,sex, body area ) Intermediate filament (keratin, 10nm )
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2- Stratum Spinosum Cuboidal or flat cells Many Desmosome (hand,foot ) keratin Intermediate filaments = Tonofilaments ( intercellular bridges )
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Stratum Spinosum
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Stratum Basale + Stratum Spinosum Stratum germinativum
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Clinical point Basal cell carcinoma, spinous cell carcinoma
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3-Stratum Granulosum 3-5 cell layers A-Basophilic granules ( Keratohyalin granules phosphorylated histidine & cystein proteins no membrane ) B-Lamellar granules (cement, Lipid) : live out of water (evaporation)
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4-Stratum Lucidum Only in thick skin, Eosinophile & more flat cells,condense more keratin filaments, no nucleus & organelles Desmosome
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5-Stratum Corneum 15-20 cell layers Lysosome activity,no organelles,only amorphous fibrous proteins Cornified or keratinized cells
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Clinical point Psoriasis,
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Cells of epidermis Keratinocyte Melanocyte Langerhans cell Merckel cell
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Melanocyte Neural crest Skin color : Melanin, caroten, Blood Eu melanin Pheomelanin (red) Basal cell layer of epidermis, hair follicle,hemidesmosome,no Desmosome with keratinocytes EM :clear,many small mitochondria,good Golgi,short RER cisterns
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Synthesis of Melanin Tyrosine ------ dopa------ dopaquinon
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Melanin Epidermal unit Femur 1000/mm2 Scrotum 2000/mm2 Different in melanin granules Tanning (sunlight),skin cancer
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Melanoma Cortisol (-) --- ACTH (+) --- hyper pigmentation : Adison dissease
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Albinism Vitiligo
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Langerhans cell Satellite cells dendritic cells Spinosum layer Bone marrow Blood, APC T cell
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Merckel cell Mechanoreceptor Free nerve ending Small dense granule(neuroendocrine) Neural crest
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Dermis 1-papillary layer (L.C.T) anchoring fiber (VII) 2-Reticular layer (D.irregular.C.T) Collagen type I,elastic network, Proteoglycans (dermatan sulfate)
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Clinical points Pemphigoid (no intercellular junction between keratinocytes,autoimmune ) Bullous Pemphigoid (interruption of dermis & epidermis junction ) Solar elastosis
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Subcutaneous tissue Hypodermis
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Skin vascular networks 1-between papillary layer & Reticular layer 2-between Derm & hypoderm 3-Derm
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DERMIS Hair follicle Sebaceous gland sweat gland Arrector pili muscle
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Hairs 60-600/cm2 Without hair Age, sex,race,body area Anagen (growth ),many years (head) Catagen, Telogen (rest ), 3-4 months (head) Sex hormones (androgens),thyroid & adrenal hormones
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Clinical points Hypertrichosis
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Atrichia
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Sebaceous gland Sebum Holocrine Testestrone,ovarian and adrenal androgens
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1-Ecrine sweat gland (merocrine secretion) Cholinergic nerves
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2-Apocrine Sweat gland (merocrine secretion) open to hair follicle sex hormones,pheromones,bacteria, Adrenergic nerves
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Clinical points Polythelia
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Polymastia
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