 Hello, everybody. So today we're going to start our conversation about the nervous system. The nervous system, we're actually spending almost six lectures talking about the nervous system, which hopefully to you should indicate that, oh, this is probably an important topic. And it is. If you think about the overall function of the nervous system, its job is to basically control the whole thing. With its partner, the endocrine system, which is hormones and glands, the nervous system dictates what's going to happen in your body, as well as interprets what is going on out in the world. So I'm just going to draw you a little overview of the nervous system. And the overview, the rest of everything that we're doing is going to fit somewhere in this little picture that I'm drawing you. Okay, so these are the functions of the nervous system. First of all, the nervous system, it's almost like a funnel. So I'm going to draw you a funnel right now, like that. A funnel for what, dude and dude-esses? The nervous system is funneling in information. It's receiving information from the environment. That's one of its jobs, is to take in what's going on in the environment. And it transmits or delivers this information to an integrating center, which is actually your central nervous system, where information is processed. And you think about that, okay, information is processed. You see a bear, that's receiving information. Your brain and your spinal cord through the central nervous system have to figure out, okay, what's the scoop with this? It's a nice bear. Let's go pet the bear. Let's run like hell and find a tree to climb. Your brain has to process that information. And then the nervous system is also responsible for once the information is processed, the nervous system coordinates an action. So if the response is run like hell, then the nervous system is coordinating all the muscles that are necessary, the heart that must increase its heart rate, the eyes that must be bright and alert, the lungs that must get in enough oxygen to make sure you have energy to pull off your sprint away from the bear. The nervous system has to control and coordinate that whole thing. If you decide, oh, it's a nice bear, let's go say hi, then your nervous system is going to coordinate a different set of reactions. Hopefully, hopefully it really is a nice bear if you're going to go over and say hi to it, because if your nervous system miscalculates something like that, it can be deadly. Wow. Okay, so I'm going to give you some words to describe these three different parts of the nervous system. The parts of the nervous system that are responsible for receiving information are sensory parts. Another word for sensory things is afferent. So in the nervous system, we're going to label structures, we're going to label information, we're going to follow information pathways, we're going to be thinking about those pathways as if they're coming in, we're going to be thinking about them as afferent, I mean afferent pathways, huh? But if they're going out, what kind of pathways do you think that we're going to be calling them? Those would be our afferent pathways. Or what's the opposite of sensory? Sensory information comes in, motor information goes out. We'll talk about all of this in a great amount of detail. Motor information, you're doing something. Skeletal muscles are making stuff happen, your heart is making stuff happen. Those are all effectors that the nervous system tells them what to do. Your central nervous system consists of two structures and of course we can break down into lots of little parts that we'll remember, but the two structures that are involved are the brain and the spinal cord. You got it? Information comes in to the central nervous system, to your brain or your spinal cord. That information that's coming in is sensory or afferent information. Your spinal cord processes it, decides what to do, figures out the efferent pathway or the motor pathway that we're going to send a request for action. And then the effector or the doer, I'm going to write that word up there, coordinates action from effectors. Effectors are the organs or structures that are going to do something. This is your big picture. Through this series of processes, the nervous system coordinates the whole gig and that's why it's kind of important. Now we're going to look in the next section at the cell that is primarily responsible for doing this and that's the neuron.