1. 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 )

2. Types of epidermal papilla

3. 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

4. Type of fingerprint

6. Types of skins 1-Hairy skin (thin skin) 2-Non hairy skin (Thick skin,glabrous)

7. 400-600 75-150

8. The cell layers of epidermis 1-Stratum Basale 2-Stratum spinosum 3-Stratum Granulosum 4-Stratum Lucidum 5-Stratum Corneum 6-Stratum Disjunctivum

9. 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 )

10. 2- Stratum Spinosum Cuboidal or flat cells Many Desmosome (hand,foot ) keratin Intermediate filaments = Tonofilaments ( intercellular bridges )

11. Stratum Spinosum

12. Stratum Basale + Stratum Spinosum Stratum germinativum

13. Clinical point Basal cell carcinoma, spinous cell carcinoma

14. 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)

15. 4-Stratum Lucidum Only in thick skin, Eosinophile & more flat cells,condense more keratin filaments, no nucleus & organelles Desmosome

16. 5-Stratum Corneum 15-20 cell layers Lysosome activity,no organelles,only amorphous fibrous proteins Cornified or keratinized cells

17. Clinical point Psoriasis,

19. Cells of epidermis Keratinocyte Melanocyte Langerhans cell Merckel cell

20. 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

21. Synthesis of Melanin Tyrosine ------ dopa------ dopaquinon

24. Melanin Epidermal unit Femur 1000/mm2 Scrotum 2000/mm2 Different in melanin granules Tanning (sunlight),skin cancer

25. Melanoma Cortisol (-) --- ACTH (+) --- hyper pigmentation : Adison dissease

26. Albinism Vitiligo

27. Langerhans cell Satellite cells dendritic cells Spinosum layer Bone marrow Blood, APC T cell

28. Merckel cell Mechanoreceptor Free nerve ending Small dense granule(neuroendocrine) Neural crest

29. 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)

31. Clinical points Pemphigoid (no intercellular junction between keratinocytes,autoimmune ) Bullous Pemphigoid (interruption of dermis & epidermis junction ) Solar elastosis

32. Subcutaneous tissue Hypodermis

33. Skin vascular networks 1-between papillary layer & Reticular layer 2-between Derm & hypoderm 3-Derm

35. DERMIS Hair follicle Sebaceous gland sweat gland Arrector pili muscle

36. 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

38. Clinical points Hypertrichosis

39. Atrichia

40. Sebaceous gland Sebum Holocrine Testestrone,ovarian and adrenal androgens

41. 1-Ecrine sweat gland (merocrine secretion) Cholinergic nerves

42. 2-Apocrine Sweat gland (merocrine secretion) open to hair follicle sex hormones,pheromones,bacteria, Adrenergic nerves

43. Clinical points Polythelia

44. Polymastia