Skin Lecture PDF

SKIN DERMATOGLYPHICS (FINGERPRINTS) Certain areas of the human skin show ridges and grooves arranges in distinctive patterns, which are unique for each individual (they even differ in identical twins) stratum basale stratum basale stratum basale  L...

SKIN DERMATOGLYPHICS (FINGERPRINTS) Certain areas of the human skin show ridges and grooves arranges in distinctive patterns, which are unique for each individual (they even differ in identical twins) stratum basale stratum basale stratum basale  L Stratum granulosum TF tonofibrils K keratohyaline granules (filaggrin) L lamellar granules N nucleus remnant stratum basale stratum basale  EPIDERMIS (H+E) stratum corneum stratum lucidum stratum granulosum 2. stratum spinosum stratum germinativum 1. stratum basale basement membrane dermis EPIDERMIS (H+E) STRATUM SQUAMOUS CELLS STRATUM GRANULOSUM STRATUM GERMINATIVUM Papillary Layer  EPITHELIUM LAYERS (ON LEFT) AND CELL TYPES (ON RIGHT) Produce keratin, the major structural protein of the epidermis  MELANOCYTES Derived from neural crest Round cells with cytoplasmic (dendritic) projections that are scattered among the basal cells of the stratum basale MELANOCYTES Tyrosinase is synthesized in the rough ER, processed through the Golgi apparatus, and accumulates in vesicles (stage I melanosomes). Melanin synthesis begins in the ovoid stage II melanosomes, in which the matrix has been organized into paralel filaments on which polymerized melanin is deposited and accumulates in stage III. A mature melanin granule (stage IV) has lost tyrosinase and other activities and has the internal matrix completely filled with melanin. The mature granules are ellipsoid, approximately 0.5 by 1 μm in size, and visible by light microscopy.  from bone marrow Bind, process and present antigens to T lymphocytes, thus mediating immune response LANGERHANS CELLS  TYPES OF SKIN THICK SKIN THIN SKIN S. CORNEUM S. LUCIDUM S. GRANULOSUM S. SPINOSUM S. BASALE  EPIDERMIS AND DERMIS OF (A) THICK SKIN AND (B) THIN SKIN DERMAL PAPILLAE  EPIDERMIS DERMIS EPIDERMIS SEBACEOUS GLANDS HAIRS – CROSS SECTION SWEAT GLANDS  COLLAGEN AND ELASTIN FIBERS formed by collagen (type I) and elastic fibers regularly oriented forming lines of tension in the skin (Langer’s lines). SKIN SENSORIAL RECEPTORS Pacinian corpuscules Meissner’s corpuscules Merkel cells Ruffini’s corpuscules PACINIAN CORPUSCLE (10X, H&E)  PACINIAN CORPUSCULES MEISSNER’S CORPUSCULES RUFFINI ENDING (100X, H&E)  HYPODERMIS “Hypodermis” = below the skin “Subcutaneous” = below the skin Also called “superficial fascia” “fascia” (Latin) =band; in anatomy: sheet of connective tissue Fatty tissue which stores fat and anchors skin (areolar tissue and adipose cells) Different patterns of accumulation (male/female) HAIR FOLLICLES AND HAIRS PILO-SEBACEOUS UNIT  HAIR ROOT– CROSS SECTION (H+E) 1 –CONNECTIVE TISSUE HAIR SHEATH (DERMAL SHEATH) 1 2 – BASEMENT MEMBRANE 2 3 3 –EXTERNAL EPITHELIAL 4 HAIR ROOTH SHEAT 5 4 –EPITHELIAL STRATUM 6 LUCIDUM (HENLE’S LAYER) OF INNER EPITHELIAL HAIR ROOTH SHEAT 7 8 5 –Granular Epithelial Layer (Huxley’s Layer) Of Inner Epithelial Hair Rooth Sheat 6 –CUTICLE OF INNER ROOTH SHEATH 7 – HAIR CUTICLE 8 –HAIR CORTEX  HAIR ROOT– CROSS SECTION (H+E) 6 – BASEMENT MEMBRANE 6 5 –EXTERNAL EPITHELIAL HAIR ROOTH SHEAT 5 4 4 –EPITHELIAL STRATUM LUCIDUM (HENLE’S LAYER) OF INNER EPITHELIAL HAIR ROOTH SHEAT 3–Granular Epithelial Layer 3 (Huxley’s Layer) Of Inner Epithelial Hair Rooth Sheat 2 2 –CUTICLE OF INNER ROOTH SHEATH 1 1 –HAIR CORTEX  Phases of hair development ANAGEN active phase - A generally long period of mitotic activity and growth CATAGEN apoptosis (cell death)-driven involution, end of active growing phase of the life cycle of the hair, between growing phase (anagen) and resting stage (telogen). TELOGEN hair follicle resting phase A final long period of inactivity (telogen) during which the hair may be shed. SEBACEOUS GLANDS  SEBACEOUS GLAND (H+E) STRATUM GERMINATIVUM (SIMPLE CUBOIDAL EPITHELIUM) POLYGONAL CELLS HAIR BASEMENT HAIR MEMBRANE  TYPES OF SWEAT GLANDS ECCRINE OR MEROCRINE – Most numerous – True sweat: 99% water, some salts, traces of waste – Open through pores APOCRINE – Axillary, anal and genital areas only – Ducts open into hair follices – The organic molecules in it decompose with time - odor MODIFIED APOCRINE GLANDS – Ceruminous – secrete earwax – Mammary – secrete milk  SWEAT GLANDS MEROCRINE APOCRINE (ECCRINE) widely distributed confined to the axilary and perineal regions small lumen large lumen simple cuboideal simple cuboideal or simple epithelium columnar epithelium innervated by cholinergic innervated by fibers adrenergic nerve endings Both types of glands release their products in a merocrine way SWEAT GLANDS  SWEAT GLANDS MEROCRINE (ECCRINE) SWEAT GLANDS APOCRINE MYOEPITHELIAL CELLS  INACTIVE MAMMARY GLAND (H+E) INTERLOBULAR DUCT, SIMPLE CUBOIDAL EPITHELIUM GLANDULAR ALVEOLI- INTERLOBAR SIMPLE CONNECTIVE CUBOIDEUM TISSUE EPITHELIUM INACTIVE PREGNANCY LACTATING Mammary glands in Glands become active During lactation the lobules are adult non-pregnant during pregnancy with the even more enlarged. Lumen of women are inactive with duct system actively growing glandular alveoli (A) and small ducts and few and secretory units of excretory ducts (D) are filled lobules. Breast largely lobules becoming larger and with milk. Intralobular composed of connective highly branched. Adipocytes connective tissue is much sparse tissue and fat are present but less and difficult to see except for numerous small septa (arrows).