integumentary system

integumentary system

1. functions

   • *protects and maintains homeostasis
     • prevents water loss
     • regulates body temp
   • sensory functions
   • synthesizes vitamin d
     • ability to harvest calcium

2. layers

   • epidermis
     • features
       • no blood vessels
       • keratinized cells
         • keratin - protein synthesized by skin cells; tough, fibrous, waterproof
       • melanocytes
       • high rate of regeneration
     • layers
       • come let's get sunburned
       • stratum corneum
         • most keratin
         • no nuclei
       • stratum lucidum
         • white cells only in thick skin
       • stratum granulosum
         • granular look
       • stratum spinosum
         • spiny (desmosomes)
       • stratum basale
         • on top of basement membrane
         • mitosis
     • cells
       • keratinocytes
         • 90% of cells in epidermis
         • 4 weeks to go from stratum basale to surface
       • melanocytes
         • 8% of cells in epidermis
         • give skin its color
           • genetics
             • same # of cells, different amount of melanin and different size melanin granules
             • albinism
               • complete lack of melanin
           • environment
             • UV exposure stimulates melanocytes
           • physiology
             • kinda separate but kinda not
             • blood vessels
               • constriction = paleness, dilation= redness
               • increased O2 levels = red, decreased = blue (cyanosis)
             • jaundice
               • yellowish skin, indicates liver malfunction
         • stratum basale
         • long cellular extensions
       • langerhans cells
         • provide immunity
       • merkel cell
         • stratum basale
         • light touch receptors
   • dermis
   • hypodermis/subcutaneous