Nervous System Lecture

My great hope in sharing this information about the organization of the nervous system is to pique your curiosity about the miracle that is you and also give you some ways to hack the nervous system using the technologies of yoga to bring us into a more balanced state. So the nervous system can be subdivided into all of these different bits and pieces, but keeping our view large, the nervous system is this interconnected, interwoven, interdependent system in our body that speaks to every other system. And even though we're breaking it into parts for study, all of these parts are in crosstalk with one another at all times. The nervous system can be thought of as being subdivided into two main pieces. We have our central nervous system, sometimes referred to as the CNS, and then we have our peripheral nervous system, sometimes termed the PNS.

You have to be careful when you say that, PNS. So the central nervous system are the organs of the brain and the spinal cord, and these are actually continuous nervous system tissue, but because they have some different jobs to do, we'll label them in two different categories. Your brain is made up of 86 to 100 billion neurons. Each one of those neurons has up to 10,000 little finger-like projections called dendrites that can talk to all of the other dendrites and all of the other neurons, which means you have huge potential. So much so that you have as many connections between these neurons as there are atoms in the universe.

It's kind of a mic drop moment there. It's hard for our brain to even grasp that kind of number, that kind of concept. The brain is actually continuous with the spinal cord. The spinal cord runs down through this housing of the vertebra all the way down until around L2, L3, which is kind of your higher lower back area, and then at that point it begins to kind of fray out into these individual nerves called the horse's tail, kind of like a pony tail. It's got this horse's tail of neurons that begin to exit out through the holes in the vertebra and down and mapping through the entire body.

If it's not brain and spinal cord, if it's not central nervous system, then it's peripheral nervous system. The peripheral nervous system can be further subdivided into some bits for study. The first being somatic, sometimes termed the voluntary nervous system, voluntary control. So these are the things that we're usually a little bit more familiar with, right? I could say, go get me a glass of water, and that's kind of mean, but you could lever movement across your joints using your muscles, voluntarily bringing movement into your form to get a job done.

Slightly more mysterious to us is the autonomic nervous system. Sometimes it's termed the involuntary part of our nervous system. I don't care for that word, because involuntary sometimes sounds like, hey, it's involuntary. I have no say, no input. It's all involuntary.

And that's not at all the way it works. Autonomic comes from this root autonomy, which means a law unto itself. And so this part of our nervous system is very much influenced or affected by what's going on in our external environment and also what's going on in our internal environment. So there could be a tiger charging at you, your external environment shifts. There's a cascade of nervous system action and endocrine system functions, releasing of hormones to prepare you to fight or run from that tiger.

There's also, you could be just sitting in a nice, beautiful home with all of your comforts met and no tiger to be seen, but you could be conjuring up in your mind, got to get that email, and that guy says that to me, I'm going to say this to him. And you could be creating something that's not reality, but it'll have the same effect on your body, changes to the internal environment. So this autonomic function, even though it is involuntary, you're not trying to digest the burrito you had. You don't have to give that conscious thought. You're not trying to heartbeat, heartbeat again, heartbeat again, breathe, heartbeat again.

You would have no time for anything else. So these are functions that are involuntary, so to speak, but we very much can enter into the system. And I think the majority of the technologies of yoga, the breathing, the postures, the meditation, the visualizations, the Kriya, the sounds even, are ways to hack the autonomic nervous system to bring in either a more desirable state for what we're trying to do, or a more balanced state. So let's look at autonomic now. The autonomic can be further subdivided into a couple bits for study.

We have our sympathetic nervous system and our parasympathetic nervous system. The sympathetic nervous system is sometimes just casually referred to as the fight or flight part of our system. The parasympathetic is sometimes termed the rest and digest part of our nervous system. The sympathetic gets a really bad reputation in yoga and in kind of more holistic or naturopathic settings. Sometimes I hear from students, it's about quelling the sympathetic nervous system, turning off the sympathetic nervous system.

Sympathetic is the root of all of our troubles. It's not the case. Sympathetic is actually your superhero response. Comic activation is what allows you to run and climb and jump and laugh even and become a superhero. So if you've ever heard of a child trapped underneath a car and a tiny little mother can lift an entire car off of her child, that's because of the sympathetic nervous system.

This is the thing that comic book superheroes are made of. I think a lot of our work is to re-pattern the sympathetic nervous system, create a different relationship with the sympathetic nervous system in our yoga practice. If you get a big bang for your buck in sympathetic activation, you have a cascade of changes that will happen in your body. So say a tiger is actually coming after you. You have the arteries that lead to the skeletal muscles will dilate, bringing more blood flow.

The breath will actually increase, becoming more rapid and your bronchial passages will dilate to get more oxygen into the system. Your body knows, this intelligence in the body knows, you don't have time to digest the burrito. You don't have time to work on your lunch to get the nutrition to the cells to fight this tiger. And so instead it's like a little pick-pocketer, it'll steal glucose and fats and proteins from wherever it can, the liver, the fatty tissues, to release it directly into the system so you don't have to wait so long. Your pupils will dilate, your heartbeat races, adrenaline is produced and released through the system, all to give you a big bang for your buck reaction so you can run like the wind or fight this tiger to victory.

These are amazing things that a huge eliciting of the sympathetic nervous system will give us. But dilate back slightly and sympathetic activation will also give us the ability to take notes as you're watching this or do an asana practice or just simply to pay attention. We need to have sympathetic on, to be on, sympathetic is on. So there's nothing wrong with sympathetic, actually I hope you're in sympathetic right now, otherwise you'd be kind of daydreaming or snoring. So sympathetic is actually quite a lovely part of your own, the miracle that is you.

Sympathetic are these series of nerves that lead to the same organs actually as the sympathetic but they have an opposite reaction on them. Their job really is to maintain housekeeping functions so things that take a longer time like the reproduction system is kind of a long term process, digestion takes a while. Memory consolidation is a longer term process. So these are all immune function, right, your body is kind of always on the hunt or search for little viruses or bacteria so this is kind of a longer term job that it has to keep up with. And so this is all heightened when we're in parasympathetic nervous system activation.

When we get a huge bang for our buck in parasympathetic we might have just taken a three week vacation to Bali and did lots of restorative yoga and mantra chanting and people feeding you grapes, you might come back with a huge eliciting of parasympathetic. But dial it back slightly and this happens when you're in shavasana hopefully or when you, this is why it's kind of hard to find your shoes, sometimes after a yoga class you're a little bit kind of spacey, you've got kind of a nice hit to your parasympathetic response. Both are quite necessary and both are supposed to be just gently almost like a pendulum back and forth between it, every 88 minutes or so we're supposed to swing gently from sympathetic to parasympathetic to sympathetic to parasympathetic. The problem comes in though is sometimes we get kind of stuck in one way or the other. We either get stuck in sympathetic and we have this over activation of the sympathetic response so you might have seen this in yourself, you get asked to do one last task on a Friday night from your boss and if they had asked you that on Monday it would have been no big deal you wouldn't have even thought about it but because you've been kind of, I like to think of it like a slow drip of sympathetic, you get this hyper reactive state like, how dare you ask me to do that, I can't believe it, you know, the nerve, right?

So this is where it starts to wear on us and it actually quite literally wears down the tissues of the body when we marinate in the chemicals of the sympathetic activation. When you don't have an actual threat upon you but you're sitting in that marination of adrenaline or that you have these pickpocketers running loose, things are going to go missing in the system, you don't have the proper nutrition for yourselves. Pupils dilated and the brain activity is increasing, this leads to things like insomnia, anxiety disorders, just not being able to shut off the mind. It's almost like too many cups of coffee, right? So this is where it starts to get a little bit detrimental to the system.

Conversely, we can get stuck in parasympathetic, we can get stuck in the mud, we can get stuck in this passivity or this lethargy that we becomes undesirable when we need to get up and do our jobs or be with our families, right? So we're meant to shift gently back and forth. I think the majority of the technologies that I see in the yoga practice, the working with the breath ratios, the working with just an internal landscape vision or exploration, the deeper breathing and the postures are to reset this gentle balance. I think also the asanas are really sympathetic activating. So if you've ever been asked to hold a chair pose for more than five breaths, that's not relaxing, that's not peace and love and kissing kittens.

Your mind might start going, your body might even start shaking, you might start having some four-letter mantras about your teacher holding you in those postures. I think this is actually purposeful and hopefully your teacher is not yelling at you, stay, don't move, don't get out of here, right, freaking you out. But they're saying, perhaps, where is your breath, where is your mind, what is actually the reality of the situation, can you stay, is it appropriate to get out of here? So you begin to become discerning. So when your boss asks you that one last task on a Friday night, you can say, where is my breath, what is the reality of the situation, how do I respond rather than react?

So this, I think, is the beauty of the asana practice and some of these breathing techniques. They retrain our relationship to sympathetic and then hopefully your practice ends with something like a meditation practice or a shavasana, a restorative pose, deep breathing, something that will allow a nice reset of parasympathetic activation. Then we can leave in a state of restoration, of relaxation, in a state where we can now kind of move back and forth as we are intended to do. So I hope that this was valuable to you. Please let me know in the comments below how it's moving through your life.

Namaste.