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Local Blood Flow Regulation - Extrinsic Mechanisms

  • Local Blood Flow can also be regulated by factors extrinsic to the local tissues. These factors include neural mechanisms or hormones which affect the contraction of arterioles and pre-capillary sphincters
Neural Regulation
  • Autonomic nervous system fibers synapse on arteriolar vascular smooth muscle in many tissues but especially in the skin and skeletal muscle
  • These autonomic fibers primarily belong to the SNS and release norepinephrine on vascular smooth muscle alpha1 receptors which results in their contraction and thus vasoconstriction
  • It should be pointed out that SNS activation also induces release of epinephrine from the adrenal medulla which has a hormonal affect on arteriolar tone as discussed below