Volcanic eruptions are known to throw huge amounts of gas into the atmosphere, including carbon dioxide that are thought to increase global warming.
They spew lava, carbon dioxide and other elements into the deep oceans. The carbon gets trapped in circulating water, cycled to different regions of the ocean, where it gets caught up in upwelling currents and emitted to the atmosphere.The process can take up to 2,000 years and adds a fraction of the 88 million metric tons of carbon belched out by the volcanoes to the atmosphere.
Afferent nerve fibers carry signals from the somatic receptors to the posterior horn of the spinal cord or to the brainstem. So i beleive it is 4 but not too sure. Hope this helped a bit (:
