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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 is the opposite of vasoconstriction, which is the narrowing of blood vessels. When blood vessels dilate , the flow of blood is increased due to a decrease in vascular resistance and increase in cardiac output [ further explanation needed ] .
Reversible cerebral vasoconstriction syndrome (RCVS, sometimes called Call-Fleming syndrome) is a disease characterized by a weeks-long course of thunderclap headaches, sometimes focal neurologic signs, and occasionally seizures. [1] Symptoms are thought to arise from transient abnormalities in the blood vessels of the brain. [1]
The smooth muscle cell membranes have α and β-adrenergic receptors for these neurotransmitters. Activation of α-adrenergic receptors promotes vasoconstriction, while the activation of β-adrenergic receptors mediates the relaxation of muscle cells, resulting in vasodilation. Normally, α-adrenergic receptors predominate in smooth muscle of ...
Vascular resistance is the resistance that must be overcome for blood to flow through the circulatory system.The resistance offered by the systemic circulation is known as the systemic vascular resistance or may sometimes be called by another term total peripheral resistance, while the resistance caused by the pulmonary circulation is known as the pulmonary vascular resistance.
This secondary vasodilation caused by the primary vasoconstriction is termed functional sympatholysis, the overall effect of which on coronary arteries is dilation. [12] The target synapse of the postganglionic neuron is mediated by adrenergic receptors and is activated by either norepinephrine (noradrenaline) or epinephrine (adrenaline).
Shock is a medical emergency and requires urgent medical care. If shock is suspected, emergency help should be called immediately. While waiting for medical care, the individual should be, if safe, laid down (except in cases of suspected head or back injuries). The legs should be raised if possible, and the person should be kept warm.
Vasodilatory shock, vasogenic shock, or vasoplegic shock is a medical emergency belonging to shock along with cardiogenic shock, septic shock, allergen-induced shock and hypovolemic shock. When the blood vessels suddenly relax, it results in vasodilation.