Integumentary System Notes Anatomy by bhangrawala06


									                              The Integumentary System (skin)
   Skin accounts for 7% of your body weight
   2 distinct regions-Epidermis and Dermis
   Hypodermis, or subcutaneous tissue, isn’t really a part of the skin
     Adipose and connectivetissue anchors skin to muscles and lets skin slide
     Shock absorber and insulator
   Epidermis-thick, keratinized; stratified squamous; you make a new epidermis every
    25-45 days
     4 cell types:
         Keratinocytes: make keratin, fibrous protein that protects; held by
            desmosomes; made in the deepest layer (stratum basale) and start to make
            keratin as they are pushed up
         Melanocytes: make melanin, protects from UV light, found in deepest layer
         Langerhan’s Cells: arise from bone marrow, epidermal dentritic cells;
         Merkel Cells: found with nerves, used in touch
   Layers of epidermis
     Thick skin (palm, fingertips, soles of feet)= five layers
     Thin skin (rest of body)= 4 layers
     From deep to superficial
         Stratum Basale attached to dermis, youngest layer, has Keratinocytes; rapid
            cell division; also called stratum germinativum; same melanocytes
         Stratum Spinosum several cell layers thick, spiny projections when viewed
            on a slide, langerhan’s cells present
         Stratum Granulosum 3-5 cell layers, keratinocytes flatten, nuclei begin to
            disintegrate; accumulate kerato-hyaline and lamellated granules, cell starts to
            die; waterproofs the skin
         Stratum Lucidum clear layer, flattened and dead keratinocytes (only in thick
         Stratum Corneum 20-30 cell layers thick, cell layers are dead keratin cells
   Dermis
     Strong, flexible, contains fibroblasts, macrophages (immune), mast cells, white
        blood cells, all 3 fiber types-collagen, elastic, reticular; is the “hide” in animals
     Many nerves, blood vessels, hair follicles, and lymphatic vessels
     2 layers:
         Papillary Layer thin, superficial layer at tip; lots of blood vessels
             Dermal Papillae-indent epidermis, have nerve endings for pain and touch
                 (meissners corpustles), dermal ridges cause epidermal ridges AKA
         Reticular Layer 80% of dermis, dense irregular connective tissue, lines of
            cleavage, seperations between bundles
             Striae: stretch marks
             Blister: separation of epidermis from dermis
             Flexure Lines: dermal folds near joints on wrists, fingers, toes, etc.
   Skin Color: 3 Pigments
 Melanin only one made in skin; yellow, redish-brown, or black in color; made
  my melanocytes
   Black and brown skinned people have more, darker melanin that is kept by
      keratinocytes longer
   Freckles and moles are local accumulations of melanin
   Protects us from UV radiation which can cause skin cancer and a decreased
      immune response
 Carotene yellow to orange color, found in stratum corneum, seen best in palms,
  and soles of feet (not the same as keratin)
 Hemoglobin pink
   Caucasion skin has less melanin, so hemoglobin’s color shows through
 Cyanosis: skin appears blue due to lack of oxygen
 Jaundice: yellow in skin caused by liver disorder
 Erythema: skin reddening, blushing
 Hematoma: bruises, appear black/blue, blood clot under skin
 Pallor: pale skin sometimes due to anemia
 Bronzing: bronze, metallic sheen to skin due to malfunction of the adrenal cortex

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