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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.
His experiment was iconic because it was the first to demonstrate the endogenous release of a chemical substance that could cause a response in the absence of electrical stimulation. It paved the way for the understanding that the electrical signaling event (action potential) causes a chemical event (release of neurotransmitter from synapses ...
Vagusstoff transmitted inhibition from the vagus nerves, and Acceleransstoff transmitted stimulation from the sympathetic nerves to the heart. [31] Loewi took some years to commit himself with respect to the nature of the Stoffe , but in 1926 he was sure that Vagusstoff was acetylcholine, writing in 1936 [ 32 ] "I no longer hesitate to identify ...
Upon leaving the medulla oblongata between the olive and the inferior cerebellar peduncle, the vagus nerve extends through the jugular foramen, then passes into the carotid sheath between the internal carotid artery and the internal jugular vein down to the neck, chest, and abdomen, where it contributes to the innervation of the viscera, reaching all the way to the colon.
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The 1921 discovery by Otto Loewi of Vagusstoff using frog hearts resulted in the identification of acetylcholine as the first neurotransmitter. [10] Enkephalin using bioassays such as the mouse vas deferens as a bioassay. [11] Nitric oxide using both assays of bull retractor penis and aortic ring. [12]
He then proceeded to prove this hypothesis by well-designed experiments, repeated numerous times to consolidate evidence, and with meticulously detailed methodology. This work rebutted a claim made by the eminent French pathologist Jean Cruveilhier that phlebitis led to clot development and that thus coagulation was the main consequence of ...
Keith Lucas' experiments in the first decade of the twentieth century proved that muscles contract entirely or not at all, this was referred to as the all-or-none principle. [40] Edgar Adrian observed nerve fibers in action during his experiments on frogs. This proved that scientists could study nervous system function directly, not just ...