WEBVTT 00:00:02.041 --> 00:00:04.543 Voiceover: Before we get to exactly how 00:00:04.543 --> 00:00:06.217 chronic bronchitis happens, 00:00:06.217 --> 00:00:07.486 I just wanted to review a quick 00:00:07.486 --> 00:00:09.526 rule of thumb about the body. 00:00:09.526 --> 00:00:11.242 So this is any opening, 00:00:11.242 --> 00:00:13.108 the body has to the outside. 00:00:13.108 --> 00:00:15.613 Let's label this as the outside. 00:00:15.613 --> 00:00:17.470 And anytime you have an opening 00:00:17.470 --> 00:00:20.761 and irritants get into the body, it could be, 00:00:20.761 --> 00:00:22.900 by irritants I mean anything that doesn't belong there 00:00:22.900 --> 00:00:25.235 that inflames a tissue. 00:00:25.235 --> 00:00:28.634 A common first defense of the body is to call on 00:00:28.634 --> 00:00:31.994 the glands which are embedded in tissue. 00:00:31.994 --> 00:00:36.394 To secrete either liquid or mucous into the space. 00:00:36.394 --> 00:00:40.063 And the goal is to have this fluid, this mucous 00:00:40.063 --> 00:00:42.110 mixed with the irritants and eventually 00:00:42.110 --> 00:00:44.313 flush them out or bring them out. 00:00:44.313 --> 00:00:46.176 I'm sure you can think of examples 00:00:46.176 --> 00:00:47.426 of what I'm talking about, 00:00:47.426 --> 00:00:48.971 like tears. 00:00:49.197 --> 00:00:50.741 If things get in your eye, 00:00:50.741 --> 00:00:52.541 it makes your eyes tear, right? 00:00:52.541 --> 00:00:53.823 So this is a mechanical thing 00:00:53.823 --> 00:00:56.931 the tears actually flush out the irritant in your eye. 00:00:56.931 --> 00:00:59.930 And we have snot. 00:00:59.930 --> 00:01:00.900 I'm sorry this is kind of gross, 00:01:00.900 --> 00:01:02.923 but if things get in your nose 00:01:02.923 --> 00:01:04.172 and it's not suppose to be there, 00:01:04.172 --> 00:01:06.280 the snot has to bring it out. 00:01:06.280 --> 00:01:08.792 And the third thing which has to do with what 00:01:08.792 --> 00:01:09.612 we're going to talk about today 00:01:09.612 --> 00:01:11.740 is of course phlegm. 00:01:11.740 --> 00:01:14.604 So when things get into your throat or your lungs, 00:01:14.604 --> 00:01:16.989 the walls of the lungs secrete the mucous 00:01:16.989 --> 00:01:19.077 which forms a phlegm. 00:01:19.077 --> 00:01:20.836 Now the system in the lungs also 00:01:20.836 --> 00:01:22.700 triggers a cough reflex, 00:01:22.700 --> 00:01:25.068 which so the walls here 00:01:25.068 --> 00:01:27.988 if you can me drawing in red here. 00:01:27.988 --> 00:01:31.236 The walls here are lined with smooth muscle, 00:01:31.236 --> 00:01:34.509 and when the area is being irritated, 00:01:34.509 --> 00:01:35.775 the smooth muscle spasm 00:01:35.775 --> 00:01:37.480 and that's how we get the cough reflex 00:01:37.480 --> 00:01:38.976 to bring the phlegm out. 00:01:39.054 --> 00:01:41.216 Now keep in mind, I said this is the body's 00:01:41.216 --> 00:01:42.468 first line of defense. 00:01:42.468 --> 00:01:44.734 So these are good things to have, 00:01:44.734 --> 00:01:47.039 you want the body to do this. 00:01:47.039 --> 00:01:48.995 So chronic bronchitis is basically 00:01:48.995 --> 00:01:50.804 too much of a good thing. 00:01:50.804 --> 00:01:54.060 So we have over production of mucous, 00:01:54.060 --> 00:01:56.689 such that the body cannot clear it 00:01:56.689 --> 00:01:58.985 too much of a good thing, 00:01:58.985 --> 00:02:01.577 that's when we have chronic bronchitis. 00:02:01.577 --> 00:02:05.072 And of course itis just means it's being irritated, 00:02:05.072 --> 00:02:07.142 and bronch refers to the lungs. 00:02:07.142 --> 00:02:10.789 So chronic inflammation and irritation of the lungs. 00:02:10.789 --> 00:02:13.089 Alrighty, let's draw some airway. 00:02:13.089 --> 00:02:15.036 So we have our trachea, 00:02:15.036 --> 00:02:20.036 the big stem bronchus branch off into their branches. 00:02:20.299 --> 00:02:22.475 Here you go, just keep going. 00:02:22.475 --> 00:02:24.953 There are 20 or 30 branches to this, 00:02:24.953 --> 00:02:25.496 you get the idea, 00:02:25.496 --> 00:02:27.696 they keep getting smaller and smaller. 00:02:27.696 --> 00:02:29.608 It's how our lungs expand. 00:02:29.608 --> 00:02:33.342 And as you know oxygen goes into our lungs 00:02:33.342 --> 00:02:36.950 and carbon dioxide from the body gets out. 00:02:36.950 --> 00:02:39.053 So you have irritants in there 00:02:39.053 --> 00:02:42.041 flooding what is usually a clear path, 00:02:42.041 --> 00:02:43.509 then the lungs are not going to like that. 00:02:43.509 --> 00:02:46.640 One of the most common chronic irritants 00:02:46.640 --> 00:02:48.277 that we have in our lungs 00:02:48.277 --> 00:02:50.229 is of course cigarette smoking. 00:02:50.229 --> 00:02:53.248 So, here we go, we're going to light this cigarette. 00:02:53.248 --> 00:02:58.206 And where you see a smoke rising from the cigarette 00:02:58.206 --> 00:03:00.078 is actually billions and billions of particles 00:03:00.078 --> 00:03:02.668 that can enter and lodge into our lungs. 00:03:02.668 --> 00:03:06.820 As a response the glands in the side of the walls, 00:03:06.820 --> 00:03:08.700 they start secreting the mucous. 00:03:08.700 --> 00:03:11.310 Remember it's part of our normal response 00:03:11.310 --> 00:03:12.752 to irritation. 00:03:12.752 --> 00:03:13.861 But of course chronics, 00:03:13.861 --> 00:03:16.333 we're talking about years and years of constant. 00:03:16.333 --> 00:03:18.317 Everyday it's like this. 00:03:18.317 --> 00:03:20.714 Now eventually, what's suppose to be a clear pathway 00:03:20.714 --> 00:03:23.332 becomes convoluted with the mucous. 00:03:23.332 --> 00:03:26.963 It's like, if you're drinking through a straw from a cup, 00:03:26.963 --> 00:03:29.688 instead of having a clear straw, 00:03:29.688 --> 00:03:32.128 you're sucking on a milkshake. 00:03:32.128 --> 00:03:36.085 So this milkshake is thick and it's clogging the straw. 00:03:36.085 --> 00:03:37.202 So you'll have to suck harder 00:03:37.202 --> 00:03:39.242 and work harder to get through. 00:03:39.242 --> 00:03:40.827 Likewise, with the mucous, 00:03:40.827 --> 00:03:42.910 sometimes there's so much build up 00:03:42.910 --> 00:03:46.962 that it can clog off one little branch of the lungs. 00:03:46.962 --> 00:03:49.291 So no more gas exchange can take place here 00:03:49.291 --> 00:03:52.106 and depending on the severity of the disease 00:03:52.106 --> 00:03:54.570 you can have different areas of the lungs 00:03:54.570 --> 00:03:56.778 being out of commission because of the mucous. 00:03:56.778 --> 00:03:58.850 Now of course we always talk about smoking, 00:03:58.850 --> 00:04:00.337 but there are other things 00:04:00.337 --> 00:04:02.012 that can lead to chronic bronchitis. 00:04:02.012 --> 00:04:04.444 One important thing is pollution. 00:04:04.444 --> 00:04:06.868 Again pollutants are also billions 00:04:06.868 --> 00:04:09.573 of particles in the air all the time. 00:04:09.573 --> 00:04:12.115 In some countries that's especially a big problem 00:04:12.115 --> 00:04:14.640 and chronic bronchitis is very common there. 00:04:14.640 --> 00:04:16.154 Or we can have coal dust, 00:04:16.154 --> 00:04:18.060 for people who work in coal mines, 00:04:18.060 --> 00:04:21.037 or people who work with asbestos. 00:04:21.037 --> 00:04:22.955 Shipyard workers. 00:04:22.955 --> 00:04:25.618 The common theme here is 00:04:25.618 --> 00:04:27.721 it happens when we can inhale irritant 00:04:27.721 --> 00:04:29.635 and it happens everyday. 00:04:29.635 --> 00:04:31.241 Now if I just smoke for a few days 00:04:31.241 --> 00:04:32.265 and I have a lot of mucous, 00:04:32.265 --> 00:04:35.409 that doesn't qualify me for having chronic bronchitis. 00:04:35.409 --> 00:04:38.393 The pathophysiology here talks about 00:04:38.393 --> 00:04:40.689 the overgrowth of the glands. 00:04:40.689 --> 00:04:42.977 So we actually look for tissue change. 00:04:42.977 --> 00:04:45.950 Now in a patient, to diagnose chronic bronchitis 00:04:45.950 --> 00:04:47.913 is usually a clinical diagnosis, 00:04:47.913 --> 00:04:49.251 which means there are no test, 00:04:49.251 --> 00:04:51.663 it's just from the story. 00:04:51.663 --> 00:04:53.447 But we know from examining lungs of people 00:04:53.447 --> 00:04:54.783 who have passed away, 00:04:54.783 --> 00:04:56.866 the tissue change actually happens. 00:04:56.866 --> 00:04:59.130 So I just blew up one branch of the airway here. 00:04:59.130 --> 00:05:01.100 We'll call this the lumen. 00:05:01.100 --> 00:05:02.876 The lumen just means the inside of the tube. 00:05:02.876 --> 00:05:04.731 So the lumen is here, 00:05:04.731 --> 00:05:06.571 where the air is getting through. 00:05:06.571 --> 00:05:09.003 So the black space on both sides 00:05:09.003 --> 00:05:11.867 are the walls of the bronchi. 00:05:11.867 --> 00:05:15.484 So basically if we take a cross section of our airway, 00:05:15.484 --> 00:05:18.971 in the middle here is the lumen. 00:05:18.971 --> 00:05:20.561 And right now I'm going to talk about 00:05:20.561 --> 00:05:23.473 the wall space of the bronchi. 00:05:23.473 --> 00:05:26.533 Okay so we have some smooth muscle 00:05:26.533 --> 00:05:28.797 around the walls. 00:05:28.797 --> 00:05:30.812 Again this spasm in this 00:05:30.812 --> 00:05:32.801 is what gives us the cough reflex. 00:05:32.801 --> 00:05:35.593 And right near the surface close to the lumen 00:05:35.593 --> 00:05:39.338 we have these layers of glands. 00:05:39.338 --> 00:05:41.034 They're responsible for the mucous production 00:05:41.034 --> 00:05:42.291 we've been talking about. 00:05:42.291 --> 00:05:45.107 As you can see they are right under the surface. 00:05:45.107 --> 00:05:49.042 The job is to secrete things into the lumen. 00:05:49.042 --> 00:05:50.122 Okay just for completeness 00:05:50.122 --> 00:05:53.090 let me draw some irritants in the lumen. 00:05:53.090 --> 00:05:54.311 Okay. 00:05:54.311 --> 00:05:58.151 So that's what a normal wall usually looks like. 00:05:58.866 --> 00:06:01.334 There is a way for us to put a number on this. 00:06:01.334 --> 00:06:02.695 And we only do this, 00:06:02.695 --> 00:06:06.405 we've only seen this in people who have passed away 00:06:06.405 --> 00:06:08.141 and their lungs get caught up in the lab, 00:06:08.141 --> 00:06:09.542 and we can look under the microscope 00:06:09.542 --> 00:06:11.747 to see the Reid index. 00:06:11.747 --> 00:06:14.556 Which is a way to calculate the ratio of the glands, 00:06:14.556 --> 00:06:17.546 the thickness of the glands to the whole wall. 00:06:17.546 --> 00:06:21.859 Now normal Reid index is less than 40%. 00:06:21.859 --> 00:06:23.950 So we can see the thickness here 00:06:23.950 --> 00:06:26.781 versus the thickness of this whole wall. 00:06:26.781 --> 00:06:29.570 It should be less than 40% in you or me. 00:06:29.570 --> 00:06:30.630 And of course in the middle here 00:06:30.630 --> 00:06:31.958 there are other things like cartilage 00:06:31.958 --> 00:06:33.741 or connective tissue. 00:06:33.741 --> 00:06:35.502 We're just going to fill it in a little bit. 00:06:36.587 --> 00:06:38.884 Now what happens in chronic bronchitis is, 00:06:38.884 --> 00:06:43.442 the actual thickness of the gland layer grows. 00:06:43.442 --> 00:06:47.041 So the glands start proliferating, 00:06:47.041 --> 00:06:49.656 because we need so much mucous 00:06:49.656 --> 00:06:51.800 that the original number is not enough, 00:06:51.800 --> 00:06:54.220 so the body is recruited to make more glands 00:06:54.220 --> 00:06:58.277 and they extend towards the smooth muscle. 00:06:58.277 --> 00:07:00.341 So in chronic bronchitis, 00:07:00.341 --> 00:07:03.756 the Reid index is usually over 50%. 00:07:03.756 --> 00:07:06.154 So definitely more than half of the thickness 00:07:06.154 --> 00:07:08.913 of the whole wall is made of glands. 00:07:08.913 --> 00:07:11.214 Now remember we cannot do this in living people 00:07:11.214 --> 00:07:14.094 because we have to cut away their lungs. 00:07:14.094 --> 00:07:17.118 So just a way for us to put a number on this disease, 00:07:17.118 --> 00:07:19.079 but usually the patients are diagnosed 00:07:19.079 --> 00:07:21.537 and treated according to their symptoms. 00:07:21.537 --> 00:07:23.822 And the symptoms all come from this tissue change 00:07:23.822 --> 00:07:26.811 and the over production of mucous.