INTEGUMENTARY SYS

INTEGUMENTARY SYS - THE INTEGUMENTARY SYSTEM Skin...

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Unformatted text preview: THE INTEGUMENTARY SYSTEM Skin (Integument) Skin Regions: (outer to inner) H Epidermis H Dermis H Hypodermis (subcutaneous CT) Figure 5.1 Skin structure . Epidermis Hair shaft Dermis Reticular layer Papillary layer Hypodermis (superficial fascia) Dermal papillae Pore Subpapillary vascular plexus Appendages of skin Eccrine sweat gland Arrector pili muscle Sebaceous (oil) gland Hair follicle Hair root Nervous structures Sensory nerve fiber Pacinian corpuscle Hair follicle receptor (root hair plexus) Cutaneous vascular plexus Adipose tissue Epidermis Keratinized stratified squamous epithelium Outermost protective shield - exposed to the external environment 4 cell types Cell Types of Epidermis Cells of the Epidermis Keratinocytes Arise in deepest layer, lost at surface H Produce the fibrous protein keratin H Produce glycolipid (water sealant) H Desmosomes, tight junctions Cells of the Epidermis Melanocytes Produce pigment melanin pigment shield H Protection against UV radiation Merkel cells Associated with sensory nerve endings H Merkel disc = touch receptor Epidermal dendritic cells (Langerhans cells) Help activate the immune system Figure 5.2 The main structural features of the skin epidermis. Melanocyte Melanin granule Tactile (Merkel) cell Sensory nerve ending Epidermal dendritic cell Dermis Dermis Keratinocytes Desmosomes (b) (a) Stratum corneum Most superficial layer; 2030 layers of dead cells represented only by flat membranous sacs filled with keratin. Glycolipids in extracellular space. Stratum granulosum Three to five layers of flattened cells, organelles deteriorating; cytoplasm full of lamellated gran- ules (release lipids) and keratohyaline granules. Stratum spinosum Several layers of keratinocytes unified by desmosomes. Cells contain thick bundles of intermediate filaments made of pre-keratin. Stratum basale Deepest epidermal layer; one row of actively mitotic stem cells; some newly formed cells become part of the more superficial layers. See occasional melanocytes and epidermal dendritic cells. Stratified Epidermis 4-5 Strata Basal layer to Apical layer H Cells accumulate more keratin H Cell membrane thickens H Cells change shape H Cell death Attached to underlying dermis Single row of mitotic keratinocytes Cuboidal/columnar shape Melanocytes, Merkels Stratum Basale (Stratum Germinativum) 8-10 layers of polyhedral-shaped (spiny) cells Pre-keratin Melanin granules Epidermal dendritic cells Desmosomes Stratum Spinosum...
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INTEGUMENTARY SYS - THE INTEGUMENTARY SYSTEM Skin...

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