Editing Vasoconstriction (section)

{{short description|Narrowing of blood vessels due to the constriction of smooth muscle cells}}
{{Infobox anatomy
| Name = Vasoconstriction
| Latin =
| Greek =
| Image = {{Multiple image
   | image1 = Cardiovascular system - Vasoconstriction 1 -- Smart-Servier.png
   | width1 = 100
   | image2 = Cardiovascular system - Vasoconstriction 3 -- Smart-Servier.png
   | width2 = 100
   | border = infobox
   | image_gap = 30
}}
| Caption = Schematic depiction of relaxed vessel wall (left) and vasoconstriction (right)
| Width =
| Image2 = Microvessel.jpg
| Caption2 = [[Transmission electron microscopy|Transmission]] [[Micrograph|electron micrograph]] showing vasoconstriction of a [[microvessel]]  by [[pericyte]]s and [[endothelial cell]]s resulting in the deformation of an [[erythrocyte]] (E)
}}

'''Vasoconstriction''' is the narrowing of the [[blood vessel]]s resulting from contraction of the muscular wall of the vessels, in particular the large [[arteries]] and small [[arterioles]]. The process is the opposite of [[vasodilation]], the widening of blood vessels. The process is particularly important in controlling [[hemorrhage]] and reducing acute blood loss. When blood vessels constrict, the flow of blood is restricted or decreased, thus retaining body heat or increasing [[vascular resistance]].  This makes the [[skin]] turn paler because less blood reaches the surface, reducing the radiation of heat. On a larger level, vasoconstriction is one mechanism by which the body regulates and maintains [[mean arterial pressure]].

Medications causing vasoconstriction, also known as vasoconstrictors, are one type of [[antihypotensive agent|medicine used to raise blood pressure]]. Generalized vasoconstriction usually results in an increase in systemic blood pressure, but it may also occur in specific tissues, causing a localized reduction in blood flow. The extent of vasoconstriction may be slight or severe depending on the substance or circumstance. Many vasoconstrictors also cause [[pupillary response|pupil dilation]]. Medications that cause vasoconstriction include: [[antihistamine]]s, [[decongestant]]s, and [[stimulant]]s. Severe vasoconstriction may result in symptoms of [[intermittent claudication]].<ref>{{cite web|url=https://www.drugs.com/pro/medihaler-ergotamine.html|title=Medihaler Ergotamine|website=[[drugs.com]]|access-date=2016-05-20}}</ref>