Vasoconstriction

Vasoconstriction (from Latin vas vessel ' and constringere, to tie up ') is the medical term for vasoconstriction. Vasoconstriction occurs primarily through small arteries and arterioles. These blood vessels are referred to as resistance vessels, as they are the actual resistance of the blood flow. At a constriction of the vessels of the resistance is increased, thereby reducing the flow rate of the blood. In addition, the blood flow decreased after the affected section of the vessel. Local vasoconstriction and vasodilation (widening of blood vessels ) thus serve primarily the regulation of organ perfusion.

Trigger

Vasoconstriction is primarily caused by hormones, which (eg noradrenaline to the α - receptors) bind in the blood vessels to certain receptors. Vasoconstrictive agents are also known as vasoconstrictors.

Vasoconstrictor hormones angiotensin I and II, serotonin, thromboxane A2, endothelin formed by peripheral tissue cells, norepinephrine, and in very high concentrations, the vasodilatory otherwise effective adrenaline.

Neurological correlations

Sympathetic efferent neurogenic vasoconstrictor effect, under his influence, the vascular basic tone is increased to the resting tone: transection of sympathetic fibers in the periphery leads to reddening of the skin due to vasodilation.

In 5 % of newborns, located at the hypothalamic vasomotor center is not yet mature, so the lack of vasoconstriction leads to a harlequin color change.