Nervous System Foundations 02 The Autonomic Nervous System

So today we're going to touch on what is the autonomic nervous system.

So the autonomic nervous system is a portion of what we would call the peripheral nervous system.

The peripheral nervous system is responsible for controlling our involuntary or more automatic actions in the body.

So things such as blood pressure,

Respiration rate,

Urination,

Digestion,

Sexual arousal.

These things are all governed by our autonomic nervous system.

Our autonomic nervous system is further divided into technically three divisions.

The two that most people would recognize are our sympathetic nervous system and our parasympathetic nervous system.

The third division of that is something called the enteric nervous system.

The enteric nervous system is the sensory interface through our digestive systems.

The other two divisions that we just mentioned,

The sympathetic and parasympathetic divisions,

Are what we'll focus on primarily here.

So like we said,

Autonomic nervous system is regulating our more automatic processes in the body.

So things that we don't have control over.

We tend to have more control over things like movement,

Where our limbs are in space,

What we're touching,

Our temperature,

Etc.

In this case,

These are the things that our body doesn't have as much voluntary or cognitive control over.

The sympathetic and parasympathetic branches of the autonomic nervous system tend to work complementary to each other.

I guess you could say they're kind of opposites to each other,

But they're very complementary to each other.

They're interacting constantly and we're having this kind of wave of back and forth between the two of them.

And in a healthy regulated nervous system,

We can bounce between both of these states very easily.

So the sympathetic angle of the autonomic nervous system is what happens when we're exposed to a threat.

And conversely,

The parasympathetic branch of our autonomic nervous system is what's more activated when we're feeling generally more safe.

That's not to say that the sympathetic system isn't activated when we're feeling safe.

It's just the one that tends to get more activated the more we're exposed to a threat.

So what happens?

Let's dive into the parasympathetic nervous system first.

When we're generally feeling safe,

Our heart rate is a little lower.

Our respiratory rate is lower.

Our blood flow tends to be,

You know,

Roughly everywhere in the body,

But more specifically to the gut,

The digestive system.

The smaller muscles in our body are getting good blood flow distribution.

And,

You know,

We're just more rested.

And the opposite of that is when we're in more of a sympathetic state.

So when we're exposed to a threat,

What then happens is we stimulate that sympathetic branch.

So what happens is generally our heart rate increases,

Our respiratory rate increases,

Blood flow gets diverted away from the digestive system,

From the reproductive organs,

Towards the bigger muscle groups,

Because good chance we're going to have to fight or we might have to run away.

These things are what we would consider the fight or flight aspect of that sympathetic nervous system.

So generally,

Day to day,

We're living somewhere between those two.

You know,

Maybe we're eating our lunch and we're generally really calm.

And then,

You know,

Perhaps something happens.

We get a phone call from someone we didn't expect and we suddenly jump into a little bit more of a sympathetic mode.

And then we realize the conversation is generally very safe and we calm back down.

And for the most part,

We're kind of navigating and hovering somewhere between the two of them.

If I'm exposed to something that is quite threatening,

Let's call it a tiger,

Because that's the example that's generally given.

You know,

If I live in a place where tigers are generally a threat,

If I see one that might activate my sympathetic nervous system,

Then what happens is all those mechanisms kick into place with the goal of preserving my life in the short term.

So big muscles get lots of blood flow.

Digestion,

Not so much,

Because my body's not really interested in what nutrients I have down the road.

It's very much interested in how I'm going to stay alive right now with this tiger.

Fight or flight comes from this example,

Because my options really are to fight the tiger or run away from the tiger.

Either way,

It's going to take a lot of energy.

So all the mechanisms of my body are going to work together to feed that energy in the here and now.

Once I run away or once I fight that tiger with my big,

Strong,

Heavily blood-flowed muscles,

Tiger is no longer a threat.

Generally,

I come back down into more of a parasympathetic state.

Now,

In this state,

My body is much more concerned with survival in the long term.

I want good immune system function.

I want good digestion.

I want all the muscles in my body to have good,

Good blood flow.

I want blood flow into my fingertips so I can have really good dexterity when I'm,

You know,

Whatever I'm doing with my hands.

But in general,

These two systems should work together to be on alert,

Keeping us safe while also making sure that we have everything we need to survive in the long term.

So complementary is a great word to describe how they work,

Keeping us safe in the short term and the long term.

If that's helpful,

Please let me know.

If it's not,

Also let me know because feedback is very important.

However,

I hope that that is a good description of how the autonomic nervous system works and a little bit of an insight as to how it keeps us safe.

Thanks again for watching.

Thank you very much and enjoy.