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Portion of the medulla oblongata
The vasomotor center (VMC ) is a portion of the
medulla oblongata . Together with the
cardiovascular center and
respiratory center , it regulates
blood pressure .
[1] It also has a more minor role in other
homeostatic processes.[
citation needed ] Upon increase in
carbon dioxide level at
central chemoreceptors , it stimulates the sympathetic system to constrict vessels. This is opposite to carbon dioxide in tissues causing vasodilatation, especially in the brain.
[2] Cranial nerves IX (
glossopharyngeal nerve ) and X (
vagus nerve ) both feed into the vasomotor centre and are themselves involved in the regulation of blood pressure.
Structure
The vasomotor center is a collection of integrating
neurons in the
medulla oblongata of the middle
brain stem . The term "vasomotor center" is not truly accurate, since this function relies not on a single brain structure ("center") but rather represents a network of interacting neurons.
[3]
Afferent fibres
The vasomotor center integrates nerve impulses from many places via the
solitary nucleus :
[4]
Efferent fibres
The vasomotor center gives off sympathetic fibres through the
spinal cord and
sympathetic ganglia , which reach vascular smooth muscle.
[6]
Function
The vasomotor center changes
vascular smooth muscle
tone .
[1]
[5] This changes local and systemic
blood pressure .
[1]
A drop in blood pressure leads to increased sympathetic tone from the vasomotor center.
[7] This acts to raise blood pressure.
[7]
Clinical significance
Methyldopa acts on the vasomotor center, leading to selective stimulation of
α2 -adrenergic receptor .
[8]
Guanfacine also causes the same stimulation.
[9] This reduces
sympathetic tone to vascular smooth muscle.
[9] This reduces
heart rate and
vascular resistance .
[9]
Digoxin increases
vagal tone from the vasomotor centre, which decreases
pulse .
[7]
G-series
nerve agents have their most potent effect in the vasomotor center.
[10] Unlike other parts of the body, where continued stimulation of
acetylcholine receptors leads to recoverable
paralysis , overstimulation of the vasomotor center is often causes a fatal rise in blood pressure.
[11]
History
The localization of vasomotor center was determined by
Filipp Ovsyannikov in 1871.
[10]
See also
References
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b
c Sear, John W. (January 1, 2019), Hemmings, Hugh C.; Egan, Talmage D. (eds.),
"26 - Antihypertensive Drugs and Vasodilators" , Pharmacology and Physiology for Anesthesia (Second Edition) , Philadelphia: Elsevier, pp. 535–555,
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^
"Bionic blood pressure device being developed at Vanderbilt" . Retrieved October 6, 2008 .
^ Guyenet, Patrice G. (May 2006). "The sympathetic control of blood pressure". Nature Reviews. Neuroscience . 7 (5): 335–346.
doi :
10.1038/nrn1902 .
ISSN
1471-003X .
PMID
16760914 .
S2CID
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^ Northcott, Carrie A.; Haywood, Joseph R. (January 1, 2007), Lip, Gregory Y. H.; Hall, John E. (eds.), "Chapter 25 - Central Nervous System Control of Blood Pressure", Comprehensive Hypertension , Philadelphia: Mosby, pp. 281–290,
doi :
10.1016/b978-0-323-03961-1.50028-3 ,
ISBN
978-0-323-03961-1
^
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b Schwarzwald, Colin C.; Bonagura, John D.; Muir, William W. (January 1, 2009), Muir, William W.; Hubbell, John A. E. (eds.),
"Chapter 3 - The Cardiovascular System" , Equine Anesthesia (Second Edition) , Saint Louis: W.B. Saunders, pp. 37–100,
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^ Touyz, Rhian M. (January 1, 2014), Willis, Monte S.; Homeister, Jonathon W.; Stone, James R. (eds.),
"Chapter 14 - Blood Pressure Regulation and Pathology" , Cellular and Molecular Pathobiology of Cardiovascular Disease , San Diego: Academic Press, pp. 257–275,
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c Waller, Derek G.; Sampson, Anthony P. (January 1, 2018), Waller, Derek G.; Sampson, Anthony P. (eds.),
"7 - Heart failure" , Medical Pharmacology and Therapeutics (Fifth Edition) , Elsevier, pp. 131–142,
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ISBN
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^ O'Shaughnessy, Kevin M. (January 1, 2012), Bennett, Peter N.; Brown, Morris J.; Sharma, Pankaj (eds.),
"Chapter 24 - Arterial hypertension, angina pectoris, myocardial infarction and heart failure" , Clinical Pharmacology (Eleventh Edition) , Oxford: Churchill Livingstone, pp. 393–427,
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c Rizzo, Renata; Gulisano, Mariangela (January 1, 2013), Martino, Davide; Cavanna, Andrea E. (eds.),
"Chapter Fourteen - Clinical Pharmacology of Comorbid Attention Deficit Hyperactivity Disorder in Tourette Syndrome" , International Review of Neurobiology , Advances in the Neurochemistry and Neuropharmacology of Tourette Syndrome, 112 , Academic Press: 415–444,
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10.1016/b978-0-12-411546-0.00014-7 ,
PMID
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^
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b Owsjannikow, PH. Die tonischen und reflektorischen Centren der Gefäßnerven. / Berichte ueber die Verhandlungen der
Königlich Sächsischen Gesellschaft der Wissenschaften zu Leipzig (1871) 23.
^ Abdollahi, M.; Mostafalou, S. (January 1, 2014),
"G-Series Nerve Agents" , in Wexler, Philip (ed.), Encyclopedia of Toxicology (Third Edition) , Oxford: Academic Press, pp. 800–805,
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