Arteries and Arterioles

• Arteries


  Blood vessels that carry oxygenated blood away from the heart to the organs
• Arteries


  • Wall is relatively thick to withstand high blood pressure
  • Outer layer is rich in collagen for structural strength
  • Contains a layer of smooth muscle to control blood flow
  • Contains a layer of elastic fibers to help keep blood moving smoothly
• Lumen


  The central cavity of the artery where the blood flows
• Endothelial cells


  Thin layer lining the lumen to reduce friction as blood flows
• Arterioles


  Smaller blood vessels that branch off from arteries to deliver blood to capillaries
• Arterioles


  • Collagen-rich outer layer and elastic layer are relatively thin compared to arteries
  • Smooth muscle layer is relatively thicker compared to arteries
  • Involved in controlling blood flow to capillaries through vasoconstriction and vasodilation
• Vasoconstriction is when smooth muscle in arterioles contracts, reducing blood flow through capillaries
• Vasodilation is when smooth muscle in arterioles relaxes, increasing blood flow through capillaries
• Arteries


  • Have thick muscular walls to resist high pressure leaving the heart
• Arteries and arterioles


  1. Able to adjust diameter

  2. To adjust blood supply and blood pressure
• Tunica intima


  • Endothelial cell layer (cell)
  • Smooth to reduce friction
  • Basement membranes
• Tunica media

  • Elastic connective tissue - stretches for pressure changes
  • Smooth muscle
• Tunica media


  • Stretch for changes in flow and pressure
• Tunica adventitia


  • Collagen, elastin
  • Resists over-stretching