Search results
Results From The WOW.Com Content Network
In most cases, vagal tone is not measured directly. Instead the processes affected by the vagus nerve – specifically heart rate and heart rate variability – are measured and used as a surrogate for vagal tone. Increased vagal tone (and thus vagal action) is generally associated with a lower heart rate and increased heart rate variability.
This is a potential cause of vomiting due to the inability of the proximal stomach smooth muscle to undergo receptive relaxation. The vagal afferents are activated during the gastric phase of digestion when the corpus and fundus of the stomach are distended secondary to the entry of a food bolus. The stimulation of the mechanical receptors ...
Vagusstoff (literally translated from German as "Vagus Substance") refers to the substance released by stimulation of the vagus nerve which causes a reduction in the heart rate. Discovered in 1921 by physiologist Otto Loewi , vagusstoff was the first confirmation of chemical synaptic transmission and the first neurotransmitter ever discovered.
The vagus nerve plays a crucial role in heart rate regulation by modulating the response of sinoatrial node; vagal tone can be quantified by investigating heart rate modulation induced by vagal tone changes. As a general consideration, increased vagal tone (and thus vagal action) is associated with a diminished and more variable heart rate.
Methyldopa acts on the vasomotor center, leading to selective stimulation of α 2-adrenergic receptor. [8] Guanfacine also causes the same stimulation. [9] This reduces sympathetic tone to vascular smooth muscle. [9] This reduces heart rate and vascular resistance. [9] Digoxin increases vagal tone from the vasomotor centre, which decreases ...
Activity is increased via sympathetic stimulation of the cardioaccelerator nerves, and inhibited via parasympathetic stimulation by the vagus nerve. During rest vagal stimulation normally predominates as, left unregulated, the SA node would initiate a sinus rhythm of approximately 100 bpm. [1]
A vagal maneuver is an action used to stimulate the parasympathetic nervous system by activating the vagus nerve. The vagus nerve is the longest nerve of the autonomic nervous system and helps regulate many critical aspects of human physiology, including heart rate, blood pressure, sweating, and digestion through the release of acetylcholine .
The stimulation of the J-receptors causes a reflex increase in breathing rate, and is also thought to be involved in the sensation of dyspnea, the subjective sensation of difficulty breathing. [ 4 ] [ 5 ] The reflex response that is produced is apnea followed by rapid breathing, bradycardia , and hypotension (pulmonary chemoreflex).