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Episodes of vasovagal syncope are typically recurrent and usually occur when the predisposed person is exposed to a specific trigger. Before losing consciousness, the individual frequently experiences early signs or symptoms such as lightheadedness, nausea, the feeling of being extremely hot or cold (accompanied by sweating), ringing in the ears, an uncomfortable feeling in the heart, fuzzy ...
The vagovagal reflex is active during the receptive relaxation of the stomach in response to swallowing of food (prior to it reaching the stomach). When food enters the stomach a "vagovagal" reflex goes from the stomach to the brain, and then back again to the stomach causing active relaxation of the smooth muscle in the stomach wall.
Excessive activation of the vagal nerve during emotional stress, which is a parasympathetic overcompensation for a strong sympathetic nervous system response associated with stress, can also cause vasovagal syncope due to a sudden drop in cardiac output, causing cerebral hypoperfusion. Vasovagal syncope affects young children and women more ...
Vagal tone is activity of the vagus nerve (the 10th cranial nerve) and a fundamental component of the parasympathetic branch of the autonomic nervous system.This branch of the nervous system is not under conscious control and is largely responsible for the regulation of several body compartments at rest.
Vasovagal syncope can be considered in two forms: Isolated episodes of loss of consciousness, unheralded by any warning symptoms for more than a few moments. These tend to occur in the adolescent age group and may be associated with fasting, exercise, abdominal straining, or circumstances promoting vaso-dilation (e.g., heat, alcohol).
It has been theorized that exhibiting vasovagal response when exposed to blood was evolutionarily advantageous, and that this phobia is a vestige of an ancestral evolutionary mechanism. [ 8 ] [ 9 ] Fainting may have acted as a form of tonic immobility , [ 8 ] allowing primitive humans to play dead in a situation where blood was being spilled ...
A frequent type of syncope, termed vasovagal syncope is originated by intense cardioinhibition, mediated by a sudden vagal reflex, that causes transitory cardiac arrest by asystole and/or transient total atrioventricular block. [1] [2] It is known as “Vaso-vagal Syncope”, “Neurocardiogenic Syncope” or “Neurally-mediated Reflex Syncope ...
Micturition syncope or post-micturition syncope is the name given to the human phenomenon of fainting shortly after or during urination. The underlying cause is not fully understood, but it may be a result of vasovagal response , postural hypotension , or a combination thereof.