0:00:02.041,0:00:04.543 Voiceover: Before we get to exactly how 0:00:04.543,0:00:06.217 chronic bronchitis happens, 0:00:06.217,0:00:07.486 I just wanted to review a quick 0:00:07.486,0:00:09.526 rule of thumb about the body. 0:00:09.526,0:00:11.242 So this is any opening, 0:00:11.242,0:00:13.108 the body has to the outside. 0:00:13.108,0:00:15.613 Let's label this as the outside. 0:00:15.613,0:00:17.470 And anytime you have an opening 0:00:17.470,0:00:20.761 and irritants get into[br]the body, it could be, 0:00:20.761,0:00:22.900 by irritants I mean anything[br]that doesn't belong there 0:00:22.900,0:00:25.235 that inflames a tissue. 0:00:25.235,0:00:28.634 A common first defense[br]of the body is to call on 0:00:28.634,0:00:31.994 the glands which are embedded in tissue. 0:00:31.994,0:00:36.394 To secrete either liquid[br]or mucous into the space. 0:00:36.394,0:00:40.063 And the goal is to have[br]this fluid, this mucous 0:00:40.063,0:00:42.110 mixed with the irritants and eventually 0:00:42.110,0:00:44.313 flush them out or bring them out. 0:00:44.313,0:00:46.176 I'm sure you can think of examples 0:00:46.176,0:00:47.426 of what I'm talking about, 0:00:47.426,0:00:48.971 like tears. 0:00:49.197,0:00:50.741 If things get in your eye, 0:00:50.741,0:00:52.541 it makes your eyes tear, right? 0:00:52.541,0:00:53.823 So this is a mechanical thing 0:00:53.823,0:00:56.931 the tears actually flush out[br]the irritant in your eye. 0:00:56.931,0:00:59.930 And we have snot. 0:00:59.930,0:01:00.900 I'm sorry this is kind of gross, 0:01:00.900,0:01:02.923 but if things get in your nose 0:01:02.923,0:01:04.172 and it's not suppose to be there, 0:01:04.172,0:01:06.280 the snot has to bring it out. 0:01:06.280,0:01:08.792 And the third thing[br]which has to do with what 0:01:08.792,0:01:09.612 we're going to talk about today 0:01:09.612,0:01:11.740 is of course phlegm. 0:01:11.740,0:01:14.604 So when things get into[br]your throat or your lungs, 0:01:14.604,0:01:16.989 the walls of the lungs secrete the mucous 0:01:16.989,0:01:19.077 which forms a phlegm. 0:01:19.077,0:01:20.836 Now the system in the lungs also 0:01:20.836,0:01:22.700 triggers a cough reflex, 0:01:22.700,0:01:25.068 which so the walls here 0:01:25.068,0:01:27.988 if you can me drawing in red here. 0:01:27.988,0:01:31.236 The walls here are lined[br]with smooth muscle, 0:01:31.236,0:01:34.509 and when the area is being irritated, 0:01:34.509,0:01:35.775 the smooth muscle spasm 0:01:35.775,0:01:37.480 and that's how we get the cough reflex 0:01:37.480,0:01:38.976 to bring the phlegm out. 0:01:39.054,0:01:41.216 Now keep in mind, I[br]said this is the body's 0:01:41.216,0:01:42.468 first line of defense. 0:01:42.468,0:01:44.734 So these are good things to have, 0:01:44.734,0:01:47.039 you want the body to do this. 0:01:47.039,0:01:48.995 So chronic bronchitis is basically 0:01:48.995,0:01:50.804 too much of a good thing. 0:01:50.804,0:01:54.060 So we have over production of mucous, 0:01:54.060,0:01:56.689 such that the body cannot clear it 0:01:56.689,0:01:58.985 too much of a good thing, 0:01:58.985,0:02:01.577 that's when we have chronic bronchitis. 0:02:01.577,0:02:05.072 And of course itis just[br]means it's being irritated, 0:02:05.072,0:02:07.142 and bronch refers to the lungs. 0:02:07.142,0:02:10.789 So chronic inflammation and[br]irritation of the lungs. 0:02:10.789,0:02:13.089 Alrighty, let's draw some airway. 0:02:13.089,0:02:15.036 So we have our trachea, 0:02:15.036,0:02:20.036 the big stem bronchus branch[br]off into their branches. 0:02:20.299,0:02:22.475 Here you go, just keep going. 0:02:22.475,0:02:24.953 There are 20 or 30 branches to this, 0:02:24.953,0:02:25.496 you get the idea, 0:02:25.496,0:02:27.696 they keep getting smaller and smaller. 0:02:27.696,0:02:29.608 It's how our lungs expand. 0:02:29.608,0:02:33.342 And as you know oxygen goes into our lungs 0:02:33.342,0:02:36.950 and carbon dioxide from the body gets out. 0:02:36.950,0:02:39.053 So you have irritants in there 0:02:39.053,0:02:42.041 flooding what is usually a clear path, 0:02:42.041,0:02:43.509 then the lungs are not going to like that. 0:02:43.509,0:02:46.640 One of the most common chronic irritants 0:02:46.640,0:02:48.277 that we have in our lungs 0:02:48.277,0:02:50.229 is of course cigarette smoking. 0:02:50.229,0:02:53.248 So, here we go, we're going[br]to light this cigarette. 0:02:53.248,0:02:58.206 And where you see a smoke[br]rising from the cigarette 0:02:58.206,0:03:00.078 is actually billions and[br]billions of particles 0:03:00.078,0:03:02.668 that can enter and lodge into our lungs. 0:03:02.668,0:03:06.820 As a response the glands[br]in the side of the walls, 0:03:06.820,0:03:08.700 they start secreting the mucous. 0:03:08.700,0:03:11.310 Remember it's part of our normal response 0:03:11.310,0:03:12.752 to irritation. 0:03:12.752,0:03:13.861 But of course chronics, 0:03:13.861,0:03:16.333 we're talking about years[br]and years of constant. 0:03:16.333,0:03:18.317 Everyday it's like this. 0:03:18.317,0:03:20.714 Now eventually, what's[br]suppose to be a clear pathway 0:03:20.714,0:03:23.332 becomes convoluted with the mucous. 0:03:23.332,0:03:26.963 It's like, if you're drinking[br]through a straw from a cup, 0:03:26.963,0:03:29.688 instead of having a clear straw, 0:03:29.688,0:03:32.128 you're sucking on a milkshake. 0:03:32.128,0:03:36.085 So this milkshake is thick[br]and it's clogging the straw. 0:03:36.085,0:03:37.202 So you'll have to suck harder 0:03:37.202,0:03:39.242 and work harder to get through. 0:03:39.242,0:03:40.827 Likewise, with the mucous, 0:03:40.827,0:03:42.910 sometimes there's so much build up 0:03:42.910,0:03:46.962 that it can clog off one[br]little branch of the lungs. 0:03:46.962,0:03:49.291 So no more gas exchange[br]can take place here 0:03:49.291,0:03:52.106 and depending on the[br]severity of the disease 0:03:52.106,0:03:54.570 you can have different areas of the lungs 0:03:54.570,0:03:56.778 being out of commission[br]because of the mucous. 0:03:56.778,0:03:58.850 Now of course we always[br]talk about smoking, 0:03:58.850,0:04:00.337 but there are other things 0:04:00.337,0:04:02.012 that can lead to chronic bronchitis. 0:04:02.012,0:04:04.444 One important thing is pollution. 0:04:04.444,0:04:06.868 Again pollutants are also billions 0:04:06.868,0:04:09.573 of particles in the air all the time. 0:04:09.573,0:04:12.115 In some countries that's[br]especially a big problem 0:04:12.115,0:04:14.640 and chronic bronchitis[br]is very common there. 0:04:14.640,0:04:16.154 Or we can have coal dust, 0:04:16.154,0:04:18.060 for people who work in coal mines, 0:04:18.060,0:04:21.037 or people who work with asbestos. 0:04:21.037,0:04:22.955 Shipyard workers. 0:04:22.955,0:04:25.618 The common theme here is 0:04:25.618,0:04:27.721 it happens when we can inhale irritant 0:04:27.721,0:04:29.635 and it happens everyday. 0:04:29.635,0:04:31.241 Now if I just smoke for a few days 0:04:31.241,0:04:32.265 and I have a lot of mucous, 0:04:32.265,0:04:35.409 that doesn't qualify me for[br]having chronic bronchitis. 0:04:35.409,0:04:38.393 The pathophysiology here talks about 0:04:38.393,0:04:40.689 the overgrowth of the glands. 0:04:40.689,0:04:42.977 So we actually look for tissue change. 0:04:42.977,0:04:45.950 Now in a patient, to[br]diagnose chronic bronchitis 0:04:45.950,0:04:47.913 is usually a clinical diagnosis, 0:04:47.913,0:04:49.251 which means there are no test, 0:04:49.251,0:04:51.663 it's just from the story. 0:04:51.663,0:04:53.447 But we know from examining lungs of people 0:04:53.447,0:04:54.783 who have passed away, 0:04:54.783,0:04:56.866 the tissue change actually happens. 0:04:56.866,0:04:59.130 So I just blew up one[br]branch of the airway here. 0:04:59.130,0:05:01.100 We'll call this the lumen. 0:05:01.100,0:05:02.876 The lumen just means[br]the inside of the tube. 0:05:02.876,0:05:04.731 So the lumen is here, 0:05:04.731,0:05:06.571 where the air is getting through. 0:05:06.571,0:05:09.003 So the black space on both sides 0:05:09.003,0:05:11.867 are the walls of the bronchi. 0:05:11.867,0:05:15.484 So basically if we take a[br]cross section of our airway, 0:05:15.484,0:05:18.971 in the middle here is the lumen. 0:05:18.971,0:05:20.561 And right now I'm going to talk about 0:05:20.561,0:05:23.473 the wall space of the bronchi. 0:05:23.473,0:05:26.533 Okay so we have some smooth muscle 0:05:26.533,0:05:28.797 around the walls. 0:05:28.797,0:05:30.812 Again this spasm in this 0:05:30.812,0:05:32.801 is what gives us the cough reflex. 0:05:32.801,0:05:35.593 And right near the[br]surface close to the lumen 0:05:35.593,0:05:39.338 we have these layers of glands. 0:05:39.338,0:05:41.034 They're responsible for[br]the mucous production 0:05:41.034,0:05:42.291 we've been talking about. 0:05:42.291,0:05:45.107 As you can see they are[br]right under the surface. 0:05:45.107,0:05:49.042 The job is to secrete[br]things into the lumen. 0:05:49.042,0:05:50.122 Okay just for completeness 0:05:50.122,0:05:53.090 let me draw some irritants in the lumen. 0:05:53.090,0:05:54.311 Okay. 0:05:54.311,0:05:58.151 So that's what a normal[br]wall usually looks like. 0:05:58.866,0:06:01.334 There is a way for us[br]to put a number on this. 0:06:01.334,0:06:02.695 And we only do this, 0:06:02.695,0:06:06.405 we've only seen this in[br]people who have passed away 0:06:06.405,0:06:08.141 and their lungs get caught up in the lab, 0:06:08.141,0:06:09.542 and we can look under the microscope 0:06:09.542,0:06:11.747 to see the Reid index. 0:06:11.747,0:06:14.556 Which is a way to calculate[br]the ratio of the glands, 0:06:14.556,0:06:17.546 the thickness of the[br]glands to the whole wall. 0:06:17.546,0:06:21.859 Now normal Reid index is less than 40%. 0:06:21.859,0:06:23.950 So we can see the thickness here 0:06:23.950,0:06:26.781 versus the thickness of this whole wall. 0:06:26.781,0:06:29.570 It should be less than 40% in you or me. 0:06:29.570,0:06:30.630 And of course in the middle here 0:06:30.630,0:06:31.958 there are other things like cartilage 0:06:31.958,0:06:33.741 or connective tissue. 0:06:33.741,0:06:35.502 We're just going to[br]fill it in a little bit. 0:06:36.587,0:06:38.884 Now what happens in chronic bronchitis is, 0:06:38.884,0:06:43.442 the actual thickness of[br]the gland layer grows. 0:06:43.442,0:06:47.041 So the glands start proliferating, 0:06:47.041,0:06:49.656 because we need so much mucous 0:06:49.656,0:06:51.800 that the original number is not enough, 0:06:51.800,0:06:54.220 so the body is recruited[br]to make more glands 0:06:54.220,0:06:58.277 and they extend towards the smooth muscle. 0:06:58.277,0:07:00.341 So in chronic bronchitis, 0:07:00.341,0:07:03.756 the Reid index is usually over 50%. 0:07:03.756,0:07:06.154 So definitely more than[br]half of the thickness 0:07:06.154,0:07:08.913 of the whole wall is made of glands. 0:07:08.913,0:07:11.214 Now remember we cannot[br]do this in living people 0:07:11.214,0:07:14.094 because we have to cut away their lungs. 0:07:14.094,0:07:17.118 So just a way for us to put[br]a number on this disease, 0:07:17.118,0:07:19.079 but usually the patients are diagnosed 0:07:19.079,0:07:21.537 and treated according to their symptoms. 0:07:21.537,0:07:23.822 And the symptoms all come[br]from this tissue change 0:07:23.822,0:07:26.811 and the over production of mucous.