Intima

• Intima:

  • the inner layer of the vessel is composed of a single layer of endothelial cells resting on a connective tissue basement layer
  • This endothelium serves as a physical barrier between the internal vessel wall structure and the circulating blood
  • The endothelium is so much more than a passive structural barrier, it is also a highly interactive interface between blood and vessel wall and serves as a variety of function
• Endothelial Cells Functions:

  • Secrete vasoactive substances
  • notably nitric oxide and prostacyclin, which both produce vasodilation and endothelin that promotes vasoconstriction
  • Either vasoconstriction or vasodilation are normally secreted according to need
  • Secrete many anticoagulants including prostacyclin, which physically repels platelet cells and prevents them from attaching to the endothelial wall
  • Note if platelets were to find attachment the formation of a thrombus would occur
• Endothelial Cells Functions:

  • The above endothelial functions become impaired during the process of plaque formation and result in a loss of local vasoconstriction even when needed and a shift to encourage coagulation and thrombus formation
  • It is damage to the intima/endothelium, which is the first step in atheroma development
• Vessel Architecture

  A) Intima