Visceral sensory input comes from (surprise!) the viscera, or internal organs.
These organs transmit information we associate with the five senses. Somatic sensory input comes from the receptors of the eyes, ears, nose, tongue, and skin. There are two main flavors of sensory input received by the PNS: somatic and visceral. They are (in some cases literally) the eyes and ears of the nervous system, collecting information and keeping the CNS informed so it can formulate reactions. Sensory neurons relay information about stimuli such as temperature, pressure, light, pain, and certain chemicals back to the brain. The PNS has two different kinds of pathways: sensory (afferent) and motor (efferent), and we’re going to add those to the map next. The officials there issue orders when problems arise.Īfferent and Efferent Pathways of the PNS These starships and stations interact with alien lifeforms, distant planets, and weird space anomalies, then send reports back to Starfleet HQ on Earth. You can see this distinction in the image below.īecause I’m into both metaphors and Star Trek, let’s think of the CNS as Starfleet Command and the PNS as all the exploratory vessels and research stations scattered throughout the galaxy. That’s it-all the other pieces of the nervous system belong to the PNS. The CNS is composed of the brain and the spinal cord. I placed the CNS a little higher than the PNS because even though the PNS isn’t part of the CNS, the CNS is technically “in charge.” The biggest and most basic distinction we make when talking about the nervous system is the one between the Central Nervous System (CNS) and the Peripheral Nervous System (PNS), so that’s where we’re going to start our map. The map we’re creating is going to help us learn about all of these different pieces of the nervous system, what they do, and how they communicate with each other. It turns out that when we say “the” nervous system, we’re really referring to one entity that has a bunch of different divisions that work together to achieve a common goal (keeping you alive). Well, if you’re feeling lost among the branches, never fear! The easiest way to get un-lost is to make a map, and that’s what we’re going to do today. Autonomic, parasympathetic, somatic, peripheral.how many nervous systems can one person have?! Navigating the Nervous System Part I: The CNS, PNS, and Somatic Motor ControlĪll the terminology that gets thrown around when you’re studying the nervous system can be a little overwhelming.
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