Vasomotor
Encyclopedia
Vasomotor refers to actions upon a blood vessel which alter its diameter. More specifically, it can refer to vasodilator action and vasoconstrictor action.
Currently, new research has been performed, suggesting that vasomotor topographic patterns are not consistent with traditional vasomotor nerve topography charts.
of the artery, secrete neurotransmitters such as norepinephrine
into the extracellular fluid
surrounding the smooth muscle (tunica media) from the terminal knob of the axon. The smooth muscle cell membranes have α and β-adrenergic receptors for these neurotransmitters. Activation of α-adrenergic receptors promotes vasocontriction, while the activation of β-adrenergic receptors mediates the relaxation of muscle cells, resulting in vasodilation. Normally, α-adrenergic receptors predominates in smooth muscle of resistance vessels.
, and angiotensin
are the vasocontrictors of smooth muscles while nitric oxide
and prostacyclin are vasodilators of the smooth muscles.
are known for causing reduced/increased blood flow in the tumours by vasomotor changes. Inadequate blood supply to the tumour cells can cause the cells to be radio-resistant and resulted in reduced accessibility to chemotherapeutic agents.
Injuries to nerves of the lower trunk of the brachial plexus
(Klumpke's paralysis) and compression of median nerve
at the flexor retinaculum of the hand
(Carpal Tunnel Syndrome
) can cause vasomotor changes at the areas innervated by the nerves. This area of the skin will become warmer because of vasodilation (loss of vasoconstriction).
Depression of vasomotor center
of brain can cause the loss of vasomotor tone of blood vessels, resulting in massive dilatation of veins. This will result in a condition called as neurogenic shock
.
Currently, new research has been performed, suggesting that vasomotor topographic patterns are not consistent with traditional vasomotor nerve topography charts.
Sympathetic innervation
Sympathetic nerve fibres travel around the tunica mediaTunica media
The tunica media is the middle layer of an artery or vein.-Artery:It is made up of smooth muscle cells and elastic tissue...
of the artery, secrete neurotransmitters such as norepinephrine
Norepinephrine
Norepinephrine is the US name for noradrenaline , a catecholamine with multiple roles including as a hormone and a neurotransmitter...
into the extracellular fluid
Extracellular fluid
Extracellular fluid usually denotes all body fluid outside of cells. The remainder is called intracellular fluid.In some animals, including mammals, the extracellular fluid can be divided into two major subcompartments, interstitial fluid and blood plasma...
surrounding the smooth muscle (tunica media) from the terminal knob of the axon. The smooth muscle cell membranes have α and β-adrenergic receptors for these neurotransmitters. Activation of α-adrenergic receptors promotes vasocontriction, while the activation of β-adrenergic receptors mediates the relaxation of muscle cells, resulting in vasodilation. Normally, α-adrenergic receptors predominates in smooth muscle of resistance vessels.
Endothelium derived chemicals
endothelinEndothelin
Endothelins are proteins that constrict blood vessels and raise blood pressure. They are normally kept in balance by other mechanisms, but when they are over-expressed, they contribute to high blood pressure and heart disease....
, and angiotensin
Angiotensin
Angiotensin, a peptide hormone, causes blood vessels to constrict, and drives blood pressure up. It is part of the renin-angiotensin system, which is a major target for drugs that lower blood pressure. Angiotensin also stimulates the release of aldosterone, another hormone, from the adrenal cortex...
are the vasocontrictors of smooth muscles while nitric oxide
Nitric oxide
Nitric oxide, also known as nitrogen monoxide, is a diatomic molecule with chemical formula NO. It is a free radical and is an important intermediate in the chemical industry...
and prostacyclin are vasodilators of the smooth muscles.
Pathology
Some vasoactive chemicals such as vasodilator acetylcholineAcetylcholine
The chemical compound acetylcholine is a neurotransmitter in both the peripheral nervous system and central nervous system in many organisms including humans...
are known for causing reduced/increased blood flow in the tumours by vasomotor changes. Inadequate blood supply to the tumour cells can cause the cells to be radio-resistant and resulted in reduced accessibility to chemotherapeutic agents.
Injuries to nerves of the lower trunk of the brachial plexus
Brachial plexus
The brachial plexus is a network of nerve fibers, running from the spine, formed by the ventral rami of the lower four cervical and first thoracic nerve roots...
(Klumpke's paralysis) and compression of median nerve
Median nerve
The median nerve is a nerve in humans and other animals. It is in the upper limb. It is one of the five main nerves originating from the brachial plexus....
at the flexor retinaculum of the hand
Flexor retinaculum of the hand
The flexor retinaculum is a strong, fibrous band that arches over the carpus, converting the deep groove on the front of the carpal bones into a tunnel, the carpal tunnel, through which the Flexor tendons of the digits and the median nerve pass.It is attached, medially, to the pisiform and the...
(Carpal Tunnel Syndrome
Carpal tunnel syndrome
Carpal Tunnel Syndrome is an entrapment idiopathic median neuropathy, causing paresthesia, pain, and other symptoms in the distribution of the median nerve due to its compression at the wrist in the carpal tunnel. The pathophysiology is not completely understood but can be considered compression...
) can cause vasomotor changes at the areas innervated by the nerves. This area of the skin will become warmer because of vasodilation (loss of vasoconstriction).
Depression of vasomotor center
Vasomotor center
The vasomotor center is a portion of the medulla oblongata that regulates blood pressure and other homeostatic processes. Upon blood increase in carbon dioxide it stimulates the sympathetic system to constrict vessels. This is opposite to carbon dioxide in tissues causing vasoconstriction,...
of brain can cause the loss of vasomotor tone of blood vessels, resulting in massive dilatation of veins. This will result in a condition called as neurogenic shock
Neurogenic shock
Neurogenic shock is a distributive type of shock resulting in hypotension, occasionally with bradycardia, that is attributed to the disruption of the autonomic pathways within the spinal cord. Hypotension occurs due to decreased systemic vascular resistance resulting in pooling of blood within the...
.