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The sympathetic nervous system's primary process is to stimulate the body's fight or flight response. It is, however, constantly active at a basic level to maintain homeostasis. [ 4 ] The sympathetic nervous system is described as being antagonistic to the parasympathetic nervous system. The latter stimulates the body to "feed and breed" and to ...
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 process is particularly important in controlling hemorrhage and reducing acute blood loss.
Injuries to nerves of the lower trunk of the brachial plexus (Klumpke's paralysis) and compression of median nerve at the flexor retinaculum of the hand (Carpal Tunnel Syndrome) can cause vasomotor changes at the areas innervated by the nerves. This area of the skin will become warmer because of vasodilation (loss of vasoconstriction). [5]
Serotonin (/ ˌsɛrəˈtoʊnɪn, ˌsɪərə -/) [6][7][8] or 5-hydroxytryptamine (5-HT) is a monoamine neurotransmitter. Its biological function is complex, touching on diverse functions including mood, cognition, reward, learning, memory, and numerous physiological processes such as vomiting and vasoconstriction. [9]
Baroreflex. The baroreflex or baroreceptor reflex is one of the body's homeostatic mechanisms that helps to maintain blood pressure at nearly constant levels. The baroreflex provides a rapid negative feedback loop in which an elevated blood pressure causes the heart rate to decrease. Decreased blood pressure decreases baroreflex activation and ...
Agonists of alpha-2 receptors in the vascular smooth muscle lead to vasoconstriction. However, in clinical practice drugs applied intravenously that are agonists of alpha-2 receptors such as clonidine lead to powerful vasodilation, which causes a decrease in blood pressure by presynaptic activation of the receptors in the sympathetic ganglia ...
Both of these factors affect pH and, in turn, the balance between vasodilation versus vasoconstriction in the brain. [3] [4] So, the blood vessels found specifically in the brain respond changes in dissolved carbon dioxide levels. Coronary (heart) circulation is controlled at the local level primarily by metabolic control mechanism. More ...
The canonical haemodynamic response function (HRF). The spike indicates a brief intense period of neuron stimulation, which requires increased blood and nutrient flow. As the needs of the neuronal activity are met, blood flow returns to homeostatic levels. In haemodynamics, the body must respond to physical activities, external temperature, and ...