Breathing Control
The Respiratory Center Find out how the respiratory center collects information from all over the body and then helps regulate your breathing. Rishi is a pediatric infectious disease physician and works at Khan Academy. These videos do not provide medical advice and are for informational purposes only. The videos are not intended to be a substitute for professional medical advice, diagnosis or treatment. Always seek the advice of a qualified health provider with any questions you may have regarding a medical condition. Never disregard professional medical advice or delay in seeking it because of something you have read or seen in any Khan Academy video.
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- so, in this video what I wanted to focus on is one
- particular area of the brain, actually 2 areas I'm going to sketch out, not just one
- but I'm going to show you how I think that these 2 areas can be kind of uh
- united in a way, so these 2 areas when 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 2 areas and these neurons are going to be communicating
- lets say this neuron sends a little axon 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 coordinated ways
- that the breathing that you do is, uh, 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 2 areas, in fact sometimes its subdivided
- even further, but I kind of just put it all together and say this part
- of the brain that I'm kind of sketching out in green, this area then, is
- our respiratory center. This is going to be responsible for all the important
- activities of breathing. So let me just write that out here, "respiratory"
- "center". So, a respiratory center is going to
- gather information from different places and then its
- 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, kind of neighborhood cells
- and these cells are called the 'Central Chemo receptors'
- and 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 thats
- these guys right here. Now if you have central chemo receptors, you also
- probably can expect that there will be some peripheral chemoreceptors and these
- ones are also very important and they exist
- outside of the brain, right, 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, uh, two
- key groups: one is called the aortic body, and the other is
- called the carotid body. The aortic body and the carotid body. They're coming from
- different locations and are actually going to use different nerves to get in
- to the brain so the carotid body, for example, is going to lets say extend out
- this way, through a neuron. And that's going to be through a nerve
- called the glossopharyngeal nerve. This is
- cranial nerve number nine, also called the glossopharyngeal nerve
- glossopharyngeal. So this is one of the
- key peripheral chemoreceptors, you've also got
- some nerves or neurons kind of projecting from the
- aortic body, going through the vagus nerve. So this is our vagus nerve
- or cranial nerve number ten. It goes by two different names
- our vagus nerve. 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 is
- then mostly about chemicals
- you know in addition, there is another whole group
- of, uh, receptors called mechanoreceptors. 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 in many other locations, and so the bigger, kind of more general
- term would be mechanoreceptor and you can find them in places
- like the nose. You can find them in the lungs, in the GI (gastrointestinal) tract
- there are lots of different locations for these
- mechanoreceptors and they're all sending
- kind of their own projection over to the, uh
- the respiratory center. In fact, the lungs and the
- GI tract are going to hitch a ride in the vagus nerve and
- the nose mechanoreceptors, they're going to travel
- through another nerve that's called the trigeminal nerve
- or cranial nerve number 5. Trigeminal nerve.
- So, these are the routes that these receptors are
- going to take to get to the respiratory centre
- but how do these work exactly, these mechanoreceptors
- lets take an example. Lets say you're walking
- and you inhale some pollen. Well that's going to
- trigger one of these mechanoreceptors in your nose and
- its going to want to relay that information over to
- your respiratory center so you're going to get
- you know a little nerve impulse through that
- cranial nerve number 5. Similarly, in your lungs
- lets say you actually inhale some
- cigarette smoke and lets say the lungs don't like that
- and the mechanoreceptor feels that little particle
- its going to trigger cranial nerve number 10, the vagus nerve
- Similarly, you have the stretch receptors 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 its time to exhale. And similarly, in the
- GI tract, you can imagine. Lets 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 ten
- 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. Lets say
- someones having these emotions, right?
- Their breathing patterns may change.
- Maybe they're in pain. So these kinds of things
- are actually coming from the hypothalamus. 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 voluntary stuff that we do. Things like singing
- where you gotta control your breath or maybe
- you're playing a musical instrument or maybe,
- you're yelling or screaming, lets put yelling down here
- anything like that, you're going to want to control
- your breath, right, and so that's all voluntary
- control. So this is our voluntary control and its
- good that actually we have this mechanism so that
- we can, if we want to, we can change our breathing
- pattern but its 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'd always just be thinking
- about taking a breath so that you, you wouldn't miss
- the next breath and you know, subsequently,
- run out of air. So this is all the information coming
- into our respiratory center. Let me just scootch this over
- and I shall 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 going to just label out the motor nerves and
- some of the muscle groups. So we've got motor nerve
- and muscle groups and there are 4 key muscle
- groups that are going to be controlled by our
- respiratory center and we are gonna go through
- them kind of one by one. So the first one and
- the one that people usually always kind of 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
- kinda sits right below our lungs and when it contracts
- you take in a nice deep breath. But it doesn't
- work alone right? We've got other muscles involved
- as well and so I'm actually going to sketch out what
- these other muscle groups are and 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
- these are the muscles that kind of go between the ribs
- these are gonna help expand or pull out your ribs
- right, so these are very important for breathing as well
- A little bit lower then, you also have these
- abdominal muscles. Abdominal muscles here
- are gonna be T6 through L1. These are the levels
- where the little nerve fibers come out and
- are gonna help innervate or uh, help these muscles
- the abdominal muscles contract. So this is our 3rd
- 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. C1 through C3 and these would be the
- accessory muscles. Accessory muscles are the ones
- that uh usually I think of them as the ones around
- your neck area and they're gonna also kinda help
- pull out the ribcage 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, you know, your
- emotional status and what you're thinking about
- doing, you know voluntarily. All that information
- is going to come in and then the respiratory center has
- to decide, uh, how to kind of balance all that
- information and then on the way out, its 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 the 4 big
- groups of muscles.
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