Integumentary System

Integumentary System

1. Skin

   • epidermis
     • cells making up:
       • stem
         • undifferentiated
         • produce keratinocytes
       • keratinocytes
         • form epidermal ater barrier
         • lipids, tight junctions, insoluble proteins
         • push older cells to surface
           • stop mitosis
           • produce keratin fibers and flatten
       • tactile
       • dendritic/sentinel
         • warning/gaurd
         • originate in bone marrow
     • stratus basale: base
       • wavy, uneven
       • cubodial/low columnar stem cells
       • keratinocytes
       • touch baseement membrane
       • melanocytes and tactile cells
       • stem cells contstly produce keratinocytes
     • stratum spinosum: middle
       • layers of keratinocytes
       • thickest layer
       • deep cells go through mitosis
       • upper cells produce more keratin, nonmitotic
         • flatten
       • dendritic cells
         • desmosomes strengthen
     • stratum cornuem: top
       • dead, keratinized cells
       • resistant to abrasian, penetration, water loss
       • cells exfoliate
   • dermis
     • collagen: elastic, resticular, fibers and fibroblast
     • blood vessels, glands, nerves
     • hair follicle/nail embedded
     • wavy interlocking between dermis/epidermis
     • papillary layer: top
       • thin areolar tissue
       • near dermal papilla
       • blood vessels
       • mobile leukocytes
       • stability
     • piloerector muscles
       • hair follicles
       • respond to cold, fear, touch
         • goose bumps
       • show evolutionary history
   • hypodermis
     • subcutaneous tissue, not true skin
     • aerolar and adipose tissue
     • pad, thermoinsulation, energy reseve
     • highly ascular
       • injections absorb quickly
   • functions:
     • resist trauma/infection
     • barrier
     • Vit D synthesis
     • sensation
     • thermoregualation
     • nonverbal communication
   • thick: palms, sole of feet, fingers/toes
   • thiin: everywhere else, follicles and glands

2. Hair/Nails

   • pilus: keratinized cell from hair follicle
   • follicle: diagnoal tube dips into dermis
   • these are accessory organs
   • functions:
     • vestigial
     • vibrissae: nostrils/ear canals
     • shield eyes
     • protect fingernails, mainupulate, dig, pick

3. Glands

   • sweat: merocrine
     • duct lined by stratified cubodial or keratinocytes
   • subaceous
     • sebum
       • keeps hair strong and dry
     • mammary glands
     • flash shaped
     • short duct: open to hair follicle