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5  A  Notes  

The  Integumentary  System  

Skin  (______________)  

•  Consists  of  three  major  regions  1.  ______________  —superficial  region  2.  ___________  —middle  region  3.  ___________  (superficial  fascia)  —

deepest  region  •  Subcutaneous  layer  deep  to  skin  (not  

technically  part  of  skin)  •  Mostly  adipose  Lssue  

Figure 5.1

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  •  ____________  straLfied  squamous  epithelium    •  Cells  of  epidermis  

– KeraLnocytes—produce  fibrous  protein  ________  – Melanocytes  

•  10–25%  of  cells  in  lower  epidermis  • Produce  pigment  ________________  

– Epidermal  dendriLc  (_______________)  cells—macrophages  that  help  acLvate  immune  system    

– TacLle  (_______________)  cells—touch  receptors  

Figure 5.2a

Dermis

Stratum corneum Most superficial layer; 20–30 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 granules (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. (a)

Layers  of  the  Epidermis:  _____________________  (Basal  Layer)  •  Deepest  epidermal  layer  firmly  aZached  to  the  __________  

•  Single  row  of  __________  cells  •  Also  called  stratum  germinaLvum:  cells  undergo  rapid  _____________  

•  Journey  from  basal  layer  to  surface  – Takes  25–45  days    

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Layers  of  the  Epidermis:  _______________________________  

(Prickly  Layer)  

•  Cells  contain  a  _____________  system  of  intermediate  prekeraLn  filaments  aZached  to  desmosomes  

•  Abundant  melanin  granules  and  _____________  cells    

Layers  of  the  Epidermis:  ______________________________  

(Granular  Layer)  

•  Thin;  three  to  five  cell  layers  in  which  the  cells  ____________  

•  Keratohyaline  and  lamellated  granules  accumulate    

Layers  of  the  Epidermis:  _______________________________  

(Clear  Layer)  •  In  _________  skin  •  Thin,  transparent  band  superficial  to  the  stratum  granulosum  

•  A  few  rows  of  flat,  dead  ______________________  

Layers  of  the  Epidermis:  ____________________________  

(Horny  Layer)  

•  20–30  rows  of  dead,  flat,  keraLnized  membranous  __________  

•  ________________  of  the  epidermal  thickness  •  FuncLons  

– Protects  from  _______________  and  penetraLon  – Waterproofs  – ______________  against  biological,  chemical,  and  physical  assaults  

Figure 5.2b

Melanocyte Melanin granule

Tactile (Merkel) cell

Sensory nerve ending Epidermal

dendritic cell

Dermis

Keratinocytes Stratum corneum Most superficial layer; 20–30 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 granules (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. Desmosomes

(b)

Dermis  

•  Strong,  __________  connecLve  Lssue  •  Cells  include  fibroblasts,  macrophages,  and  occasionally  mast  cells  and  white  blood  cells  

•  Two  layers:    – _____________  – _____________  

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Figure 5.1

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

Layers  of  the  Dermis:  ________________________  

•  Papillary  layer  – Areolar  connecLve  Lssue  with  ___________  and  ___________  fibers  and  blood  vessels  

– Dermal  papillae  contain:    • Capillary  loops    • Meissner’s  corpuscles  • Free  nerve  endings    

Layers  of  the  Dermis:  _________________________  

•  ReLcular  layer  – ~____%  of  the  thickness  of  dermis  – Collagen  fibers  provide  _________  and  resiliency    

– ___________  fibers  provide  stretch-­‐recoil  properLes  

Skin  Markings:  FricLon  Ridges  

• Epidermal  ridges  lie  atop  deeper  dermal  papillary  ridges  to  form  fricLon  ridges  of  _____________________    

Figure 5.4a

Friction ridges

(a)

Openings of sweat gland ducts

Skin  Markings:  Cleavage  Lines  

• Collagen  fibers  arranged  in  bundles  form  ______________  (tension)  lines    

•  Incisions  made  _____________  to  cleavage  lines  heal  more  readily  

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Figure 5.4b

(b)

Skin  Color  •  Three  pigments  contribute  to  skin  color:  1.  ______________________  

•  Yellow  to  reddish-­‐brown  to  black,  responsible  for  dark  skin  colors  

–  Produced  in  melanocytes;  migrates  to  keraLnocytes  where  it  forms  “pigment  shields”  for  nuclei  

–  Freckles  and  pigmented  moles  »  Local  accumulaLons  of  melanin  

Skin  Color  

2. _____________  •  Yellow  to  orange,  most  obvious  in  the  palms  and  soles    

3. _______________  •  Responsible  for  the  pinkish  hue  of  skin  

Appendages  of  the  Skin  

• DerivaLves  of  the  epidermis  – ___________  glands  – _________  glands  – Hairs  and  hair  follicles  – Nails  

Sweat  Glands  •  Two  main  types  of  sweat  

(____________________)  glands  1.  __________  (merocrine)  sweat  glands—

abundant  on  palms,  soles,  and  forehead  •  Sweat:  99%  water,  NaCl,  vitamin  C,  

anLbodies,  dermcidin,  metabolic  wastes  •  Ducts  connect  to  pores  •  FuncLon  in  ________________________  

Figure 5.5b

(b) Photomicrograph of a sectioned eccrine gland (220x)

Secretory cells

Dermal connective tissue

Duct Sebaceous gland

Sweat pore

Eccrine gland

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Sweat  Glands  2. ________________  sweat  glands—

confined  to  axillary  and  anogenital  areas  •  ____________:  sweat  +  faZy  substances  and  

proteins  •  Ducts  connect  to  ________________________  •  FuncLonal  from  puberty  onward  (as  sexual  

scent  glands?)  –  Specialized  apocrine  glands  

•  Ceruminous  glands—in  external  ear  canal;  secrete  cerumen  

•  Mammary  glands  

Sebaceous  (_________)  Glands  

• Widely  distributed  • Most  develop  from  _________________  •  Become  acLve  at  puberty  •  Sebum  

– Oily  _____________  secreLon  – Bactericidal    – Solens  ________  and  _________    

Figure 5.5a

(a) Photomicrograph of a sectioned sebaceous gland (220x)

Sebaceous gland duct

Hair in hair follicle

Secretory cells

Dermal connective tissue

Sebaceous gland

Sweat pore

Eccrine gland