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Dermis

The dermis is thicker and deeper than the epidermis.

Elastic and collageous fibers are arranged in definite patterns to produce lines of tension and provide skin tone. There are many more elastic fibers in the dermis of a young person than an old one. The extensive network of blood vessels in the dermis provides nourishment to the living portion of the epidermis. The dermis also contains many sweat glands, oil-secreting glands, nerve endings, and hair follicles.

The dermis is composed of two layers, the stratum papillarosum (outer) and stratum reticularosum (inner).
  • Stratum papillarosum: in contact with epidermis, and accounts for 1/5 of entire dermis. Papillae form the base for friction ridges on fingers and toes.
  • Stratum reticularosum: fibers within this layer are more dense and organized to forma tough, flexible meshwork. It is very distensible, but can be torn when stretched too far. Linea albicans, which appear as temporary white streaks, form when a torn dermis repairs itself.
Innervation and Vascular Supply
  • Nerve supply: specialized integumentary effectors consist of smooth muscles or glands within the dermis that respond to motor impulses from central nervous system. Several types of sensory receptors respond to various tactile, pressure, temperature, tickle or pain stimuli.
  • Vascular supply: blood vessels within dermis supply nutrients to mitotically active stratum basale, and to structures of the dermis. Dermal blood vessels also play an important role in temperature regulation.
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