Autonomic Control of Blood Flow
Jim Hutchins
Objective 12: State how the autonomic nervous system regulates blood flow.
When the sympathetic nervous system is activated, blood flow to the abdominal organs is decreased, while blood flow to the muscles is increased. For a long time, scientists believed that there must be sympathetic nerve endings on blood vessels in the muscles which increased the blood flow. This belief persisted in the absence of any evidence that such nerve endings actually existed.
More recent evidence indicates that the autonomic control of blood flow is mediated by the gaseous neurotransmitter nitric oxide (NO). The response is neither purely adrenergic nor cholinergic; rather a mixture of different autonomic effects appears to increase NO release, which in turn dilates blood vessels locally and also open up the precapillary sphincters which regulate blood flow to the capillary beds.
About the author
Dr. Jim Hutchins is an adjunct instructor at Colorado School of Mines with 45 years of teaching experience spanning K-12 through medical school. He earned his PhD in Neuroscience from Baylor College of Medicine, where his dissertation focused on acetylcholine as a neurotransmitter in the human retina, followed by postdoctoral research at Vanderbilt University on visual system development. His research contributions include highly cited work on mitochondrial superoxide dismutase and synaptic pruning in the retinogeniculate system. Dr. Hutchins has authored multiple open-access textbooks in neuroscience, medical terminology, and anatomy & physiology, creating freely accessible educational resources that have saved students over $5 million in textbook costs. He is committed to open educational resources and Creative Commons licensing, believing that knowledge should be freely available to all learners.
