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Lecture 3

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Western University
Health Sciences
Health Sciences 3300A/B

Lecture  3:  The  Integumentary  System       The  integumentary  system  is  the  whole  body  covering  system  or  in  other  words,  the  skin  and  its   associated  structures  (hair,  nails,  sweat  glands,  etc).     The  Skin  =  Cutaneous  Membrane     • The  largest  organ  in  the  body   • Consists  of  two  main  parts  –  epidermis  and  dermis   • Near  the  skin  but  not  part  of  it  is  the  hypodermis  –  Sometimes  called  the  subcutaneous  layer                                                                                       Layer  of   Epidermis   Dermis   Hypodermis  (Not   Skin   actually  skin)   Location   The  top  layer  –  above  dermis   The  middle  layer  –   The  bottom  layer  –   below  epidermis   below  the  dermis   Composit Made  of  Stratified  squamous   Strong  dense  connective   Made  by  areolar   ion   epithelium.  Thinnest  layer.   tissue  (collagen  and   (packing)  and  adipose   elastic  fibers).  Thicker   (fat)  tissue.     than  epidermis.     Sub-­ 1. Stratum  corneum:  The   1. Papilary   No  sub  layers   Layers   outmost  layer,  dead   Region:   keratinocytes  with  a   Superficial   layer  of  protein  around   potion  (1/5)   them  (they  have   consists  of   undergone  keratinization   dense  irregular   now  called  corneocytes).   connective   You  will  “sluff”  off  a  lot   tissue  with  thin   overtime.  Callus  =   collagen  fibers.   abnormal  thickening   Contain  dermal   2. Stratum  lucidum:  Dead   papillae.   keratinocytes   Increases   (keratinocytes  have  died   dermis  SA.   but  have  not  finished  the   2. Reticular   keratinization).  Thick.   Region:  Deeper   3. Stratum  granulosum:   potion  of  dermis   the  keratinocytes  are  still   (4/5)  consists  of   on  the  move,  by  this   dense  irregular   point  they  have   connective   kertahyalin  granules  +   tissue  with  thick   lamellar  granules  (this   collagen  and   create  fat  that  acts  as  a   coarse  elastic   waterproof)   fibers.  Spaces   4. Stratum  spinosum:   between  fibers   Spider  like  budles  of   contain  adipose   keratinocytes,  arm  like   tissue  (fat),  hair,   processes  of  Langerhans   nerves,   cells  and  melanocytes   sebaceous   5. Stratum  basale:     glands  and   Deepest  layer.  Cuboidal/   sudoriferious   columnar  keratinocytes,   glands.    This  is   melanocytes  and  Merkel   where  ink  from   cells   a  tattoo  goes.   Features   4  main  cell  types:   a. Dermal  papillae  –   a. Acts  as  an  energy   1. Keratinocytes  –  (90%  of   fingerlike   reserve  (fat   epidermis)  tough,  carry   projections  that   storage)  –  fat   melanin,  produce  keratin   increase  surface   amount  different   2. Melanocytes  –  (8%)   area  with   between  sexes  and   produce  melanin  (color   epidermis   can  be  a   pigment)  and  protection   (numerous  in   determinant  for  sex   against  UV  light   hands  and  feet).   (where  the  fat   3. Merkel  cells  –  (least   Contain  capillary   accumulates)   numerous)  located  at   loops  (blood   b. Anchors  dermis  to   bottom  and  are  for   capillaries)  and   underlying  tissues   sensory   touch  receptors.   and  organs   4. Langerhans  cell  –  (small   b. Hair  and  nail   c. Allows  movement   fraction)  arise  from  red   follicles  are  in  the   of  muscle  tissue   blood  cells  and  pick  up   dermis.   below     invaded  species  (act  as   c. Dermis  weakens   d. Adipose  tissue  (fat)   macrophages)   over  time  =  saggy   is  predominate   skin  with  age.           Skin  Color   Pigment  =  agent  that  gives  a  certain  color     Skin  Pigment   Melanin   Carotene   Hemoglobin   Color   Ranges  from  yellow  to  red   Yellow  –  orange    (gives   The  pinkish/  reddish   (pheomelanin)  and  brown  to   egg  yolk  and  carrots   hue   black  (eumelanin)     their  color)   Features   a. Color  of  skin  and  hair   a. The  precursor   a. The  oxygen   b. Melanocytes  are   of  vitamin  A   carrying  part   melanin  producers   (good  for   of  red  blood   c. Different  skin  color  =   vision)   cells   different  amount  of   b. Stored  in   b. Blood  with   melanin  made   stratum   pigment   d. Freckles  (dark  =   corneum  and  in   moving   lentigines,  light  =   the
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