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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 ] .
The hunting reaction or hunting response is a process of alternating vasoconstriction and vasodilation in extremities exposed to cold. The term Lewis reaction is used too, named after Thomas Lewis, who first described the effect in 1930. [1] Vasoconstriction occurs first to reduce heat loss, but also results in strong cooling of the extremities.
The vascular nerves control vasodilation and vasoconstriction, which in turn lead to the control and regulation of temperature and homeostasis. Vasodilator innervation is restricted to the following sites : 1.) The vessels of the skeletal muscle are dilated by cholinergic sympathetic nerves 2.)
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.
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.
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 ...
Neurogenic shock is a distributive type of shock resulting in hypotension (low blood pressure), often with bradycardia (slowed heart rate), caused by disruption of autonomic nervous system pathways. [1] It can occur after damage to the central nervous system, such as spinal cord injury and traumatic brain injury.
The smooth muscle cells are relaxed to increase the diameter of flow, decreasing the vascular resistance. This is possible due to the direct relationship between the cardiac output, mean arterial pressure and the vascular resistance. Like vasoconstriction, vasodilation can be caused by internal and external factors.