DERMATOLOGY INTRODUCTION SKIN Largest organ Has two layers

DERMATOLOGY INTRODUCTION

SKIN: Largest organ Has two layers: Epidermis Dermis Function: . Protection against injury and dessication : stratum corneum. Protection against UV rays. Protection against microbes: stratum corneum langerhan cells mononuclear phagocytes mast cells. Protection against Ag & haptens : langerhan cell lymphocyte mast cell. Sensation. Thermoregulation : Eccrine sweat glands & blood vessels. Excretion. Maintenance of water balance. . Vit D synthesis : keratinocytes. Shock absorber

Skin Layyers 1. Epidermis Outermost layer Str. Squamous epithelium No blood vessel. Layers: deep to superficial a. Stratum basalis. Actively dividing stem cells along the basement membrane. Mitoses should be limited to this area. . Contains keratin b. Stratum spinosum • Contains desmosome. Cells are bound together by desmosomes. c. Stratum granulosum • Granular layer and have keratohyaline granules. d. Stratum lucidum. Found only in region with thick corneum. . consist flat eosinophilic or pale staining cell without nuclei. e. Stratum corneum. Anucleatic cells with keratin. Site for superficial dermatophyte infections

2. Dermis. Vascular. Support epidermis structurally & nutritionally. . Layers: a. Papillary • Loose connective tissue beneath the epidermis b. Reticular • Dense dermal collagen 3. Basement Membrane. Acts as an anchor for epidermis. . Allows movement of cells and nutrient between dermis and epidermis. . Stratum basalis attach to B. M by hemi-desmosome.

Epidermal Appendages: Hair Nail & Sweat gland