Editing Artery (section)

=== Capillaries ===
{{main|Capillaries}}
The [[capillaries]] are the smallest of the blood vessels and are part of the [[microcirculation]]. The microvessels have a width of a single cell in diameter to aid in the fast and easy [[Diffusion#Diffusion vs. bulk flow|diffusion]] of gasses, sugars and nutrients to surrounding tissues. Capillaries have no [[smooth muscle]] surrounding them and have a diameter less than that of [[red blood cells]]; a red blood cell is typically 7 micrometers outside diameter, capillaries typically 5 micrometers inside diameter. The red blood cells must distort in order to pass through the capillaries.

These small diameters of the capillaries provide a relatively large surface area for the exchange of gasses and nutrients.