CAPILLARIES

• WHAT DO CAPILLARIES FORM?

  capillary beds at exchange surfaces
• WHAT ARE CAPILLARY BEDS?

  many branched capillaries
• WHAT DO CAPILLARIES HAVE?

  narrow diameter
• WHY DO CAPILLARIES HAVE A NARROW DIAMETER?

  slow blood flow
• HOW DOES THE NARROW DIAMETER SLOW BLOOD FLOW?

  RBCs are squashed against the walls to maximise diffusion
• DESCRIBE THE MUSCLE LAYER OF CAPILLARIES?

  there isn't one
• DESCRIBE THE ELASTIC LAYER OF CAPILLARIES?

  there isn't one
• DESCRIBE THE WALL THICKNESS OF CAPILLARIES?

  one cell thick (only a lining layer)
• WHAT DOES THE ONE CELL THICK WALLS OF CAPILLARIES ALLOW FOR?

  short diffusion distance for exchanging between blood and cells
• DO CAPILLARIES HAVE VALVES?

  no