Integumentary System

external image crosssection.GIF
http://www.zoomdinosaurs.com/subjects/anatomy/skin/crosssection.GIF

As illustrated in the diagram above, the Integumentary System, or skin, is composed of several different layers each consisting of different structures.

Epidermis
  • composed of both dead and living cells
  • older cells are pushed to surface
  • organelles of older cells disintigrate and begin forming Keratin
  • contains melanocytes- cells which create melanin, which is a skin pigment

Dermis
  • contains collagen fibers, blood vessels, nerve endings, glands, sensory receptors, smooth muscles, and hair follicles
  • helps control body temp
    • when cold, blood vessels narrow, limiting heat loss
    • when hot, bood vessels widen pulling blood away from the core, allowing more heat to excape
  • contains two major types of glands
    • Sweat Glands- serves two purposes: excrete wastes from the blood, and to produce sweat, a means of cooling the body down. Sweat evaporates off of the surface of the skin, pulling away heat with it
    • Sebaceous Glands- oil glands, produce oily substance called sebrum, which keeps the epidermis flexible and waterproof
Hypodermis (also called Subcutaneous Tissue)
  • contains a fatty layer which acts as insulation