3.Integumentary system

1. Epidermis

   Annotations:

   • 1. composed of keratinized stratified squamous epithelium
   1. Sweet glands
   2. Melanocytes

      Annotations:

      • 1. produce melanin(primarily responsible for skin color)
      1. Round cell + clear cytoplasm
      2. Locate in stratum basale
   3. Sebaceous glands
   4. Hair follicles and hair
2. Dermis

   Annotations:

   • 1. composed of a dense connective tissue: - impact mechanical support -strength -thickness(e.g. papillae layer(PL), collagen fibers of the reticular layer(RL)
3. Hypodermis

   Annotations:

   • -contains large amount of adipose tissue

Annotations:

• 1.  epidermis is supported by dermis(a layer of dense fibro-elastic tissue) 2.Merges with the loose supporting tissue of hypodermis

1. Stratified squamous keratinizing epithilium

   Annotations:

   • 1.extremely thick 2.keratinized surface layer
2. Structure
   1. Epidermis(five layers)
      1. Stratum corneum(SC)

         Annotations:

         • 1. stratified squamous epithelium 2. consist of flattened, closely packed, dead cells and absent nuclei
      2. Stratum granulosum(SG)

         Annotations:

         • 1. 2-5 layers of nucleated cells 2. basophilic granules(keratohyalin)
      3. Stratum basale(SB)

         Annotations:

         • 1. single layer of cubondal cells on basement menbrane
      4. Stratum lucidum(SL)

         Annotations:

         • - homogenous line of flattened cells
      5. Stratum spinosum(SS)

         Annotations:

         • 1. 3-4 cells thick 2. polyhydral 3. basophilic
   2. Dermis(three layers)
      1. Subcutaneous layer

         Annotations:

         • 1. loose connective tissue 2. adipose tissue
      2. Reticular layer

         Annotations:

         • 1. mainly of bundle of  coarse collagenous fibres(in various direction)
      3. Papillary layer

         Annotations:

         • Consist of: 1. fine collagenous fibres 2. reticular fibre 3. elastic fibres -all interweaving with Blood vessels
   3. Hypodermis

1. abdominal skin

   Annotations:

   • 1. thin stratified squamous   2.only stratum corneum and stratum germinativum

1. Papillary layer

   Annotations:

   • 1. marrow zone of fibred dense irrugular connective tissue
2. Reticular layer

   Annotations:

   • 1. Hair follicle associated with sebaceous gland 2.also find cross section of sweet gland
   1. Hair follicle

      Annotations:

      • 1. features: extended hair bulb and the dermal papilla 2. the main mass of hair bulb= matrix(for hair growth)
   2. Sebaceous gland

      Annotations:

      • 1. simple branched acinar glands 2. appear encapsulated spherical masses form 3. Vacuolate cytoplasm( for lipid and waxy secretion)
   3. Sweet gland

      Annotations:

      • 1. simple coil tubular gland - appear in section as groups of small circular ovoid  structure