The impact of the sympathetic nervous system on blood vessels

[samy4408]

Hello, I have some trouble understanding the role of the sympathetic nervous system in vasoconstriction and vasodilatation of blood vessels, I searched and found contradicting resources, does anyone have the right answer?

 

[Godot_]

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"...can be..."? Could you please continue the quote or elaborate?

Certain vessels can get dilated by catecholamines - e.g. coronaries, pulmonary vessels (IIRC). Which does make sense, physiologically. Also I seem to remember that, while on the one hand the vessels are constricted, they get sensitized to NO, so if need be, the vasodilation gets amplified a bit.

Also, sometimes the wording can be sloppy, using "sympathetic" when the author actually means both brances of the vegetative nerve system.

 

[samy4408]

"...can be..."? Could you please continue the quote or elaborate?

Certain vessels can get dilated by catecholamines - e.g. coronaries, pulmonary vessels (IIRC). Which does make sense, physiologically. Also I seem to remember that, while on the one hand the vessels are constricted, they get sensitized to NO, so if need be, the vasodilation gets amplified a bit.

Also, sometimes the wording can be sloppy, using "sympathetic" when the author actually means both brances of the vegetative nerve system.

 

[Godot_]

Is it from a specialty textbook? (like e.g. neurology?)

 

[samy4408]

no, it is the first lines that come off when I typed "which nervous system is responsible for vasodilation"

 

[samy4408]

"...can be..."? Could you please continue the quote or elaborate?

Certain vessels can get dilated by catecholamines - e.g. coronaries, and pulmonary vessels (IIRC). Which does make sense, physiologically. Also I seem to remember that, while on the one hand the vessels are constricted, they get sensitized to NO, so if need be, the vasodilation gets amplified a bit.

Also, sometimes the wording can be sloppy, using "sympathetic" when the author actually means both brances of the vegetative nerve system.

thanks, interesting information but do you have the final answer?

 

[Godot_]

Depends on where exactly (i.e. at which organ) you look.

Vessels in organs relevant to sympathicus-associated stuff - fight, flight, fright - will get dilated. Like e.g. heart and lung. Might be true for spinal motoneuron vessels, too...

Intestinal perfusion, however, is reduced, as is the global muscle arteriolic sphincter - and overridden by the local NO-regulation. (Which, BTW, is the most relevant mechanism in the periphery, paracrine, and completely free form any neurological interference.) Because what use is having your arms full of blood when running is your choice.

Also, as a take-home-message: Google pretty often pretty much sncks at auto-answering natSci stuff. Wikipedia would be a better starting point.

 

[samy4408]

nice! thanks, man.