Lec 24 - Skin derivitives

• There are two types of hair

  • terminal hair (face and head - contains a medulla)
  • vellus hair (rest of the body - does not contain a medulla)
• The arrector pili muscle is a short muscle connected to hair bulb and up into the dermis just beneath dermal papilla and when it contracts, it makes the hairs stand straight up
• The stratum basale in the hair follicle gives rise to the matrix, internal root sheath and cells that give rise to the cuticle and cortex
• The external root sheath gives rise to the stratum basale within the dermal papilla
• The lunula of the nail contain softer keratin before it hardens - this region is opaque whereas the rest of the nail is transparent
• The nail matrix is the area that is producing keratin
• Sebaceous glands are always associated with hair follicles and secretes oily substance called sebum
• Eccrine sweat glands are simple coiled tubular glands. They secrete through merocrine secretion. They contain a secretory portion (lighter staining) and a duct portion (darker staining). They are surrounded by myoepithelial layer. They secrete a watery based secretion with a lot of electrolytes
• Sebaceous glands are simple branched acinar glands (duct is not branched). They secrete through pilosebaceous duct. Secrete through holocrine secretion (apoptosis) - so they need stem cell layer to replace the cells that are lost. They stain pale because they are filled with lipids that get washed out during slide preparation
• Myoepithelium is an epithelial lining around the secretory portions of the gland that have contractile functions to squeeze the glands secretion to the surface
• The secretory portion of the eccrine sweat glands are made up of pseudostratified cuboidal cells and the duct portion is stratified cuboidal cells (usually 2 layers)
• Apocrine sweat glands are found in armpits, genitals, and anal region. They secrete via merocrine secretion and are associated with hairs. They are simple coiled tubular glands. They also contain a layer of myoepithelium. These glands contain a large lumen
• Label the diagram

  A) epidermis

  B) dermis

  C) sebaceous gland

  D) eccrine gland

  E) arrector pili muscle

  F) internal root sheath and glassy membrane

  G) dermal papilla

  H) hair matrix

  I) sensory nerve ending

  J) apocrine gland

  K) external root sheath

  
• Label the diagram of a nail

  A) free edge

  B) nail fold

  C) lunula

  D) eponychium

  E) nail plate

  F) nail matrix

  G) nail root

  H) nail bed

  I) hyponychium

  J) nail plate

  
• What type of gland is this?

  Sebaceous

  
• What type of gland is this?

  eccrine gland

  
• What type of gland is this?

  apocrine gland

  
• The thickness of the stratum corneum varies depending on mechanic as stimuli ex. calluses