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Vasoconstriction is the narrowing of the blood vessels 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.
Vasodilation occurs as part of the process of inflammation, which is caused by several factors including presence of a pathogen, injury to tissues or blood vessels, and immune complexes. [7] In severe cases, inflammation can lead to sepsis or distributive shock. [11] Vasodilation is also a major component of anaphylaxis. [12]
If vasodilatory shock being left untreated, even brief hypotensive periods can result in myocardial and renal injury. [21] [35] It can also increased mortality in the critically ill. [21] Refractory shock has an all-cause mortality rate greater than 50% within a month [1] [dubious – discuss].
Norepinephrine causes predominately vasoconstriction with a mild increase in heart rate, whereas epinephrine predominately causes an increase in heart rate with a small effect on the vascular tone; the combined effect results in an increase in blood pressure.
Epinephrine (adrenaline) reacts with both α- and β-adrenoreceptors, causing vasoconstriction and vasodilation, respectively. Although α receptors are less sensitive to epinephrine, when activated at pharmacologic doses, they override the vasodilation mediated by β-adrenoreceptors because there are more peripheral α 1 receptors than β ...
When cardiac output goes down, catecholamines like epinephrine and norepinephrine, ADH, and angiotensin II are released, all of which cause vasoconstriction of blood vessels which increases of vascular resistance, and increased heart rate, which, increases cardiac output, and these combined effects increase blood pressure.
Adrenaline, also known as epinephrine, is a hormone and medication [10] [11] which is involved in regulating visceral functions (e.g., respiration). [ 10 ] [ 12 ] It appears as a white microcrystalline granule. [ 13 ]
Neurogenic shock may be caused by severe brain injury. [6] However, in case of increased intracranial pressure, according to the Cushing triad, blood pressure will be increased (unless decreased from hypovolemia), respirations will be irregular and bradycardia will also be a feature.