The respiratory center | Respiratory system physiology | NCLEX-RN | Khan Academy

So in this video what I wanted to focus on

is one particular area of the brain-- actually, two areas

I'm going to sketch out, not just one.

I'm going to show you how I think that these two areas can

be kind of united in a way.

So, these two areas, where I'm sketching out

these little green circles, are going

to be responsible for breathing-- how fast you

breathe, how deep you breathe.

And there are lots of little neurons in these two areas.

And these neurons are going to be communicating.

Let's say this neuron sends a little axon on down here,

maybe this guy sends an axon up here.

They're going to be communicating information

among themselves and between themselves

to kind of make sure they're working in a coordinated way

so that the breathing that you do

is the way that it should be, you know,

how fast it should be, given a particular situation.

So the way I think of it is kind of uniting these two areas.

In fact, sometimes it's subdivided even further.

I just put it all together and say this part of the brain

that I'm just sketching out in green,

this area then, is our respiratory center.

This is going to be responsible for all

of the important activities of breathing.

So let me just write that out here.

Respiratory center.

So our respiratory center is going

to gather information from different places.

And then it's going to have to make a decision

and execute based on all the information it receives.

So one key piece of information is

going to come from cells right here, neighborhood cells.

And these cells are called the central chemoreceptors.

The reason I'm calling them central

is because they're also part of the brain, right?

They're right in the same neighborhood,

and so these central chemoreceptors

don't have to go too far to communicate their information.

And specifically they're going to gather information

on things like carbon dioxide levels and pH levels.

One thing they don't do is oxygen levels.

So that's these guys right here.

So if you have central chemoreceptors

you also probably can expect that there

would be some peripheral chemoreceptors,

and these ones are also very important.

And they exist outside of the brain,

so they're going to be actually sending their information

along through neurons that are going

to extend all the way into the brain.

So for example, you might have two key groups.

One is called the aortic body and the other

is called the carotid body.

Aortic body and the carotid body.

They're coming from different locations

and are actually going to use different nerves

to get into the brain.

So the carotid body, for example,

is going to extend out this way through a neuron.

And that's going to be through a nerve called the-- right here--

called the glossopharyngeal nerve.

This is cranial nerve number nine, also

called the glossopharyngeal nerve.

So this is one of the key peripheral chemoreceptors.

You've also got some nerves or neurons projecting

from the aortic body going through the vagus nerve.

So this is our vagus nerve, or cranial nerve number 10.

It goes by two different names.

These peripheral chemoreceptors are

going to detect things like oxygen--

in fact, that's probably one of the most important things they

detect-- as well as carbon dioxide and pH.

So that's information coming to the respiratory center

from our peripheral and central chemoreceptors then

is mostly about chemicals.

In addition, there's another whole group

of receptors called mechanoreceptors.

And these ones are actually going

to be sending information about pressure.

Now you may be thinking, well, wait a second.

I thought baroreceptors told us about pressure.

And it turns out, baroreceptors are one type of mechanoreceptor

that's found inside of the blood vessels.

So there are many other types and many other locations.

And so the bigger, more general term would be mechanoreceptor.

You can find them in places like the nose,

you can find them in the lungs, in the GI tract,

so lots of different locations for these mechanoreceptors.

And they're all sending their own projection

over to the respirator center.

And in fact, the lungs and the GI tract

are going to hitch a ride in this vagus nerve

and the nose mechanoreceptors they're

going to travel through another nerve that's

called the trigeminal nerve or cranial nerve number five.

So these are the routes that these receptors

are going to take to get to that respiratory center.

But how do these work exactly, these mechanoreceptors?

Let's take an example.

Let's say you're walking and you inhale some pollen.

Well, that's going to trigger one of these mechanoreceptors

in your nose and it's going to want

to relay that information over to your respiratory center

so you're going to get a little nerve

impulse through that cranial nerve number five.

Similarly in your lungs, let's say

you actually inhale some cigarette smoke.

And let's say the lungs don't like that.

And then the mechanoreceptor feels that little particle.

It's going to trigger cranial nerve

number 10, the vagus nerve.

Similarly, you have these stretch receptors

that are in the lungs.

And these are actually kind of interesting

because what they're doing is they're saying,

hey, you know these lungs are starting to get really, really

full, really distended, and so they

want to let the respiratory center know that maybe it's

time to exhale.

And similarly, in the GI tract you can imagine,

let's say a baby is taking milk and the stomach

is getting really distended, you might also

imagine that that information would go back

to the respiratory center as well, in this case

through cranial nerve number 10.

So we have information about pressure or stretch,

we also have information about chemicals coming in.

But what about information on things like,

I don't know, things like anxiety for instance, or fear.

Let's say someone is having these emotions.

Their breathing pattern may change.

Maybe they're in pain.

So these kinds of things are actually

coming from the hypothalamus.

So this is another region of the brain that's

sending information down to the respiratory center

and helping to affect how we breathe.

And finally, this is probably the largest part

of our picture, this is our cerebrum.

And the cerebrum is responsible for all the voluntary stuff

that we do, things like singing, where

you've got to control your breath.

Or maybe you're playing a musical instrument,

or maybe you're yelling or screaming.

Let's put yelling down here.

Anything like that, you're going to want to control your breath.

And so that's all voluntary control.

So this is our voluntary control.

And it's good that actually we have this mechanism

so we can-- if we want to-- we can change our breathing


But it's also great that our respiratory center

can work on its own.

Can you imagine if you had to always think

about taking a breath?

You couldn't do anything else, right?

You couldn't sleep, you couldn't eat.

You would always just be thinking

about taking a breath so that you wouldn't

miss the next breath and subsequently run out of air.

So this is all the information coming

into our respiratory center.

Let me just scoot this over and actually show you now

what our brain can do with that information to actually make

sure that we're breathing comfortably.

This is our spinal column.

And I'm actually just going to label out

the motor nerves and some of the muscle groups.

So we've got motor nerves and muscle groups.

And there are four key muscle groups

that are going to be controlled by our respiratory center.

And we're going to go through them one by one.

So the first one, and the one that people usually always talk

about or think about, is this one right here.

This is going to be C3, C4, and C5.

So C3 through C5, and the muscle is the diaphragm.

This is the giant muscle that kind of sits right

below our lungs and when it contracts

you take in a nice deep breath.

But it doesn't work alone.

We've got other muscles involved as well.

So I'm actually going to sketch out

what these other muscle groups are.

The first one is T1 through T11.

All these levels are going to send off a little nerve.

And each nerve will go through a different intercostal muscle.

So intercostal muscles are-- these

are the muscles that kind of go between the ribs--

these are going to help expand or pull out your ribs, right?

So these are important for breathing as well.

A little bit lower then, you also

have these abdominal muscles.

Abdominal muscles here are going to be T6 through L1.

These are the levels where the little nerve

fibers come out and are going to help innervate or help

these muscles, abdominal muscles, contract.

So this is a third group of muscles

and they're controlled by these spinal levels.

And the final group would be this group up here.

So this is actually C1 through C3.

And these would be the accessory muscles.

Accessory muscles are the ones-- usually

I think of them as the ones around your neck area.

And they're going to also kind of help pull out the rib cage

and expand the lungs.

So there you have it.

You have information coming in, that's

the stuff that we started talking

about, from all the different locations,

around chemicals, information about pressure,

and your emotional status, and what

you're thinking about doing involuntarily.

All that information is going to come in

and then the respiratory center has

to decide how to kind of balance all that information.

And on the way out it's going to be

able to execute by controlling all these different muscle

groups and sending information down the motor nerves

that we just listed to these four big groups of muscles.