1 00:00:02,400 --> 00:00:04,042 so, in this video what I wanted to focus on is one 2 00:00:04,042 --> 00:00:08,233 particular area of the brain, actually 2 areas I'm going to sketch out, not just one 3 00:00:08,233 --> 00:00:11,900 but I'm going to show you how I think that these 2 areas can be kind of uh 4 00:00:11,900 --> 00:00:15,800 united in a way, so these 2 areas when I'm sketching out these little 5 00:00:15,800 --> 00:00:19,878 green circles are going to be responsible for breathing 6 00:00:19,878 --> 00:00:23,547 how fast you breathe, how deep you breathe, and there are lots of little neurons 7 00:00:23,547 --> 00:00:27,541 in these 2 areas and these neurons are going to be communicating 8 00:00:27,541 --> 00:00:31,535 lets say this neuron sends a little axon down here. Maybe this guy 9 00:00:31,535 --> 00:00:35,633 sends an axon up here. They're going to be communicating information among themselves 10 00:00:35,633 --> 00:00:39,800 and between themselves to kind of make sure they're working in coordinated ways 11 00:00:39,800 --> 00:00:43,467 that the breathing that you do is, uh, is the way that it should be 12 00:00:43,467 --> 00:00:47,696 you know, how fast it should be, given a particular situation. So, the way 13 00:00:47,696 --> 00:00:51,039 I think of it is kind of uniting these 2 areas, in fact sometimes its subdivided 14 00:00:51,039 --> 00:00:55,033 even further, but I kind of just put it all together and say this part 15 00:00:55,033 --> 00:00:59,300 of the brain that I'm kind of sketching out in green, this area then, is 16 00:00:59,300 --> 00:01:02,933 our respiratory center. This is going to be responsible for all the important 17 00:01:02,933 --> 00:01:07,467 activities of breathing. So let me just write that out here, "respiratory" 18 00:01:07,467 --> 00:01:10,633 "center". So, a respiratory center is going to 19 00:01:10,633 --> 00:01:13,900 gather information from different places and then its 20 00:01:13,900 --> 00:01:15,374 going to have to make a decision 21 00:01:15,374 --> 00:01:17,046 and execute based on all the information 22 00:01:17,046 --> 00:01:19,500 it receives. So one key piece of information 23 00:01:19,500 --> 00:01:22,833 is going to come from cells right here, kind of neighborhood cells 24 00:01:22,833 --> 00:01:26,400 and these cells are called the 'Central Chemo receptors' 25 00:01:26,400 --> 00:01:30,400 and the reason I'm calling them central is because they're also part of the brain, right 26 00:01:30,400 --> 00:01:34,400 they're right in the same neighborhood and so these central chemoreceptors don't have 27 00:01:34,400 --> 00:01:38,037 to go too far to communicate their information 28 00:01:38,037 --> 00:01:39,198 and specifically they're going to gather 29 00:01:39,198 --> 00:01:42,541 information on things like carbon dioxide levels and pH levels 30 00:01:42,541 --> 00:01:46,535 one thing they don't do is oxygen levels, so thats 31 00:01:46,535 --> 00:01:50,033 these guys right here. Now if you have central chemo receptors, you also 32 00:01:50,033 --> 00:01:54,708 probably can expect that there will be some peripheral chemoreceptors and these 33 00:01:54,708 --> 00:01:58,800 ones are also very important and they exist 34 00:01:58,800 --> 00:02:02,833 outside of the brain, right, so they're going to be actually sending their 35 00:02:02,833 --> 00:02:06,551 information along through neurons that are going to 36 00:02:06,551 --> 00:02:10,333 extend all the way into the brain so for example, you might have, uh, two 37 00:02:10,333 --> 00:02:14,033 key groups: one is called the aortic body, and the other is 38 00:02:14,033 --> 00:02:18,600 called the carotid body. The aortic body and the carotid body. They're coming from 39 00:02:18,600 --> 00:02:21,900 different locations and are actually going to use different nerves to get in 40 00:02:21,900 --> 00:02:25,267 to the brain so the carotid body, for example, is going to lets say extend out 41 00:02:25,267 --> 00:02:28,500 this way, through a neuron. And that's going to be through a nerve 42 00:02:28,500 --> 00:02:34,368 called the glossopharyngeal nerve. This is 43 00:02:34,368 --> 00:02:39,300 cranial nerve number nine, also called the glossopharyngeal nerve 44 00:02:39,300 --> 00:02:43,833 glossopharyngeal. So this is one of the 45 00:02:43,833 --> 00:02:46,535 key peripheral chemoreceptors, you've also got 46 00:02:46,535 --> 00:02:49,879 some nerves or neurons kind of projecting from the 47 00:02:49,879 --> 00:02:53,933 aortic body, going through the vagus nerve. So this is our vagus nerve 48 00:02:53,933 --> 00:02:58,967 or cranial nerve number ten. It goes by two different names 49 00:02:58,967 --> 00:03:02,133 our vagus nerve. these peripheral chemoreceptors are going to 50 00:03:02,133 --> 00:03:05,267 detect things like oxygen, in fact that's probably one of the 51 00:03:05,267 --> 00:03:09,198 most important things they detect as well as carbon dioxide and pH 52 00:03:09,198 --> 00:03:12,867 so that's information coming to the respiratory center 53 00:03:12,867 --> 00:03:15,700 from our peripheral and central chemoreceptors is 54 00:03:15,700 --> 00:03:17,833 then mostly about chemicals 55 00:03:17,833 --> 00:03:21,365 you know in addition, there is another whole group 56 00:03:21,365 --> 00:03:26,000 of, uh, receptors called mechanoreceptors. Mechanoreceptors. 57 00:03:26,000 --> 00:03:29,864 and these ones are actually going to be sending information about pressure 58 00:03:29,864 --> 00:03:32,100 now you may be thinking "well wait a second,..." 59 00:03:32,100 --> 00:03:35,204 "I thought baroreceptors told us about pressure" 60 00:03:35,204 --> 00:03:38,548 and it turns out baroreceptors are one type of mechanoreceptor 61 00:03:38,548 --> 00:03:41,533 that's found inside of the blood vessels. So there are many 62 00:03:41,533 --> 00:03:45,700 other types in many other locations, and so the bigger, kind of more general 63 00:03:45,700 --> 00:03:48,533 term would be mechanoreceptor and you can find them in places 64 00:03:48,533 --> 00:03:53,362 like the nose. You can find them in the lungs, in the GI (gastrointestinal) tract 65 00:03:53,362 --> 00:03:55,167 there are lots of different locations for these 66 00:03:55,167 --> 00:03:57,200 mechanoreceptors and they're all sending 67 00:03:57,200 --> 00:04:00,767 kind of their own projection over to the, uh 68 00:04:00,767 --> 00:04:04,369 the respiratory center. In fact, the lungs and the 69 00:04:04,369 --> 00:04:08,900 GI tract are going to hitch a ride in the vagus nerve and 70 00:04:08,900 --> 00:04:12,542 the nose mechanoreceptors, they're going to travel 71 00:04:12,542 --> 00:04:16,033 through another nerve that's called the trigeminal nerve 72 00:04:16,033 --> 00:04:19,694 or cranial nerve number 5. Trigeminal nerve. 73 00:04:19,694 --> 00:04:22,600 So, these are the routes that these receptors are 74 00:04:22,600 --> 00:04:25,367 going to take to get to the respiratory centre 75 00:04:25,367 --> 00:04:28,378 but how do these work exactly, these mechanoreceptors 76 00:04:28,378 --> 00:04:30,467 lets take an example. Lets say you're walking 77 00:04:30,467 --> 00:04:34,369 and you inhale some pollen. Well that's going to 78 00:04:34,369 --> 00:04:37,467 trigger one of these mechanoreceptors in your nose and 79 00:04:37,467 --> 00:04:40,067 its going to want to relay that information over to 80 00:04:40,067 --> 00:04:42,133 your respiratory center so you're going to get 81 00:04:42,133 --> 00:04:44,700 you know a little nerve impulse through that 82 00:04:44,700 --> 00:04:47,833 cranial nerve number 5. Similarly, in your lungs 83 00:04:47,833 --> 00:04:49,400 lets say you actually inhale some 84 00:04:49,400 --> 00:04:52,333 cigarette smoke and lets say the lungs don't like that 85 00:04:52,333 --> 00:04:54,833 and the mechanoreceptor feels that little particle 86 00:04:54,833 --> 00:04:58,703 its going to trigger cranial nerve number 10, the vagus nerve 87 00:04:58,703 --> 00:05:02,561 Similarly, you have the stretch receptors in the lungs 88 00:05:02,561 --> 00:05:04,627 and these are actually kind of interesting because 89 00:05:04,627 --> 00:05:06,627 what they're doing is they're saying "hey, you know.." 90 00:05:06,627 --> 00:05:09,994 "these lungs are starting to get really, really full, really distended" 91 00:05:09,994 --> 00:05:12,188 and so they want to let the respiratory center know 92 00:05:12,188 --> 00:05:15,361 that maybe its time to exhale. And similarly, in the 93 00:05:15,361 --> 00:05:18,794 GI tract, you can imagine. Lets say a baby is taking milk 94 00:05:18,794 --> 00:05:21,194 and the stomach is getting really distended 95 00:05:21,194 --> 00:05:24,494 you might also imagine that that information would go back 96 00:05:24,494 --> 00:05:26,394 to the respiratory center as well, in this case 97 00:05:26,394 --> 00:05:28,427 through cranial nerve number ten 98 00:05:28,427 --> 00:05:31,121 So, we have information about pressure 99 00:05:31,121 --> 00:05:32,267 or stretch. We also have information about 100 00:05:32,267 --> 00:05:35,424 chemicals coming in. But what about information 101 00:05:35,424 --> 00:05:36,755 on things like, I don't know, things like 102 00:05:36,755 --> 00:05:39,720 anxiety for instance, or fear. Lets say 103 00:05:39,720 --> 00:05:42,438 someones having these emotions, right? 104 00:05:42,438 --> 00:05:45,088 Their breathing patterns may change. 105 00:05:45,088 --> 00:05:47,755 Maybe they're in pain. So these kinds of things 106 00:05:47,755 --> 00:05:51,755 are actually coming from the hypothalamus. The hypothalamus. 107 00:05:51,755 --> 00:05:54,955 So this is another region of the brain that's sending 108 00:05:54,955 --> 00:05:57,763 information down to the respiratory center and 109 00:05:57,763 --> 00:06:01,121 helping to affect how we breathe. And finally, 110 00:06:01,121 --> 00:06:03,939 this is probably the largest part of our picture, 111 00:06:03,939 --> 00:06:06,621 this is our cerebrum and the cerebrum is responsible 112 00:06:06,621 --> 00:06:10,255 for all voluntary stuff that we do. Things like singing 113 00:06:10,255 --> 00:06:12,588 where you gotta control your breath or maybe 114 00:06:12,588 --> 00:06:14,220 you're playing a musical instrument or maybe, 115 00:06:14,220 --> 00:06:18,188 you're yelling or screaming, lets put yelling down here 116 00:06:18,188 --> 00:06:20,755 anything like that, you're going to want to control 117 00:06:20,755 --> 00:06:23,768 your breath, right, and so that's all voluntary 118 00:06:23,768 --> 00:06:27,020 control. So this is our voluntary control and its 119 00:06:27,020 --> 00:06:29,760 good that actually we have this mechanism so that 120 00:06:29,760 --> 00:06:32,499 we can, if we want to, we can change our breathing 121 00:06:32,499 --> 00:06:34,621 pattern but its also great that our respiratory center 122 00:06:34,621 --> 00:06:37,840 can work on its own. Can you imagine if you had to 123 00:06:37,840 --> 00:06:40,388 always think about taking a breath, you couldn't 124 00:06:40,388 --> 00:06:42,345 do anything else right? You couldn't sleep, 125 00:06:42,345 --> 00:06:44,342 you couldn't eat, you'd always just be thinking 126 00:06:44,342 --> 00:06:46,989 about taking a breath so that you, you wouldn't miss 127 00:06:46,989 --> 00:06:48,821 the next breath and you know, subsequently, 128 00:06:48,821 --> 00:06:52,488 run out of air. So this is all the information coming 129 00:06:52,488 --> 00:06:54,988 into our respiratory center. Let me just scootch this over 130 00:06:54,988 --> 00:06:57,388 and I shall show you now what our brain can do with 131 00:06:57,388 --> 00:06:59,992 that information to actually make sure that we're 132 00:06:59,992 --> 00:07:02,593 breathing comfortably. This is our spinal column 133 00:07:02,593 --> 00:07:06,621 and I'm going to just label out the motor nerves and 134 00:07:06,621 --> 00:07:10,020 some of the muscle groups. So we've got motor nerve 135 00:07:10,020 --> 00:07:12,388 and muscle groups and there are 4 key muscle 136 00:07:12,388 --> 00:07:15,921 groups that are going to be controlled by our 137 00:07:15,921 --> 00:07:17,593 respiratory center and we are gonna go through 138 00:07:17,593 --> 00:07:19,172 them kind of one by one. So the first one and 139 00:07:19,172 --> 00:07:21,494 the one that people usually always kind of talk about 140 00:07:21,494 --> 00:07:23,787 or think about is this one right here. This is going to 141 00:07:23,787 --> 00:07:30,020 be C3, C4 and C5. So C3 through C5 and the muscle 142 00:07:30,020 --> 00:07:33,055 is the diaphragm. This is the giant muscle that 143 00:07:33,055 --> 00:07:36,588 kinda sits right below our lungs and when it contracts 144 00:07:36,588 --> 00:07:39,095 you take in a nice deep breath. But it doesn't 145 00:07:39,095 --> 00:07:41,121 work alone right? We've got other muscles involved 146 00:07:41,121 --> 00:07:42,996 as well and so I'm actually going to sketch out what 147 00:07:42,996 --> 00:07:44,521 these other muscle groups are and the first one 148 00:07:44,521 --> 00:07:49,172 is T1 through T11, all these levels are going to 149 00:07:49,172 --> 00:07:53,166 send off a little nerve and each nerve will go through 150 00:07:53,166 --> 00:07:57,345 a different intercostal muscle. So intercostal muscles 151 00:07:57,345 --> 00:08:00,829 these are the muscles that kind of go between the ribs 152 00:08:00,829 --> 00:08:04,265 these are gonna help expand or pull out your ribs 153 00:08:04,265 --> 00:08:06,621 right, so these are very important for breathing as well 154 00:08:06,621 --> 00:08:11,230 A little bit lower then, you also have these 155 00:08:11,230 --> 00:08:12,624 abdominal muscles. Abdominal muscles here 156 00:08:12,624 --> 00:08:15,456 are gonna be T6 through L1. These are the levels 157 00:08:15,456 --> 00:08:19,687 where the little nerve fibers come out and 158 00:08:19,687 --> 00:08:23,421 are gonna help innervate or uh, help these muscles 159 00:08:23,421 --> 00:08:26,464 the abdominal muscles contract. So this is our 3rd 160 00:08:26,464 --> 00:08:30,132 group of muscles and they're controlled by these 161 00:08:30,132 --> 00:08:33,289 spinal levels and the final group would be this 162 00:08:33,289 --> 00:08:35,797 group up here. So this is actually C1 163 00:08:35,797 --> 00:08:40,021 through C3. C1 through C3 and these would be the 164 00:08:40,021 --> 00:08:42,624 accessory muscles. Accessory muscles are the ones 165 00:08:42,624 --> 00:08:44,807 that uh usually I think of them as the ones around 166 00:08:44,807 --> 00:08:47,188 your neck area and they're gonna also kinda help 167 00:08:47,188 --> 00:08:49,637 pull out the ribcage and expand the lungs. 168 00:08:49,637 --> 00:08:52,621 So there you have it, you have information coming 169 00:08:52,621 --> 00:08:54,921 in, that's the stuff that we started talking about, 170 00:08:54,921 --> 00:08:57,950 from all the different locations around chemicals 171 00:08:57,950 --> 00:09:00,755 information about pressure and, you know, your 172 00:09:00,755 --> 00:09:02,688 emotional status and what you're thinking about 173 00:09:02,688 --> 00:09:05,255 doing, you know voluntarily. All that information 174 00:09:05,255 --> 00:09:07,821 is going to come in and then the respiratory center has 175 00:09:07,821 --> 00:09:10,628 to decide, uh, how to kind of balance all that 176 00:09:10,628 --> 00:09:12,955 information and then on the way out, its going to be 177 00:09:12,955 --> 00:09:16,294 able to execute by controlling all these different 178 00:09:16,294 --> 00:09:18,355 muscle groups and sending information down 179 00:09:18,355 --> 00:09:21,126 the motor nerves that we just listed to the 4 big 180 00:09:21,126 --> 00:09:22,667 groups of muscles.