1
00:00:02,041 --> 00:00:04,543
Voiceover: Before we get to exactly how

2
00:00:04,543 --> 00:00:06,217
chronic bronchitis happens,

3
00:00:06,217 --> 00:00:07,486
I just wanted to review a quick

4
00:00:07,486 --> 00:00:09,526
rule of thumb about the body.

5
00:00:09,526 --> 00:00:11,242
So this is any opening,

6
00:00:11,242 --> 00:00:13,108
the body has to the outside.

7
00:00:13,108 --> 00:00:15,613
Let's label this as the outside.

8
00:00:15,613 --> 00:00:17,470
And anytime you have an opening

9
00:00:17,470 --> 00:00:20,761
and irritants get into
the body, it could be,

10
00:00:20,761 --> 00:00:22,900
by irritants I mean anything
that doesn't belong there

11
00:00:22,900 --> 00:00:25,235
that inflames a tissue.

12
00:00:25,235 --> 00:00:28,634
A common first defense
of the body is to call on

13
00:00:28,634 --> 00:00:31,994
the glands which are embedded in tissue.

14
00:00:31,994 --> 00:00:36,394
To secrete either liquid
or mucous into the space.

15
00:00:36,394 --> 00:00:40,063
And the goal is to have
this fluid, this mucous

16
00:00:40,063 --> 00:00:42,110
mixed with the irritants and eventually

17
00:00:42,110 --> 00:00:44,313
flush them out or bring them out.

18
00:00:44,313 --> 00:00:46,176
I'm sure you can think of examples

19
00:00:46,176 --> 00:00:47,426
of what I'm talking about,

20
00:00:47,426 --> 00:00:48,971
like tears.

21
00:00:49,197 --> 00:00:50,741
If things get in your eye,

22
00:00:50,741 --> 00:00:52,541
it makes your eyes tear, right?

23
00:00:52,541 --> 00:00:53,823
So this is a mechanical thing

24
00:00:53,823 --> 00:00:56,931
the tears actually flush out
the irritant in your eye.

25
00:00:56,931 --> 00:00:59,930
And we have snot.

26
00:00:59,930 --> 00:01:00,900
I'm sorry this is kind of gross,

27
00:01:00,900 --> 00:01:02,923
but if things get in your nose

28
00:01:02,923 --> 00:01:04,172
and it's not suppose to be there,

29
00:01:04,172 --> 00:01:06,280
the snot has to bring it out.

30
00:01:06,280 --> 00:01:08,792
And the third thing
which has to do with what

31
00:01:08,792 --> 00:01:09,612
we're going to talk about today

32
00:01:09,612 --> 00:01:11,740
is of course phlegm.

33
00:01:11,740 --> 00:01:14,604
So when things get into
your throat or your lungs,

34
00:01:14,604 --> 00:01:16,989
the walls of the lungs secrete the mucous

35
00:01:16,989 --> 00:01:19,077
which forms a phlegm.

36
00:01:19,077 --> 00:01:20,836
Now the system in the lungs also

37
00:01:20,836 --> 00:01:22,700
triggers a cough reflex,

38
00:01:22,700 --> 00:01:25,068
which so the walls here

39
00:01:25,068 --> 00:01:27,988
if you can me drawing in red here.

40
00:01:27,988 --> 00:01:31,236
The walls here are lined
with smooth muscle,

41
00:01:31,236 --> 00:01:34,509
and when the area is being irritated,

42
00:01:34,509 --> 00:01:35,775
the smooth muscle spasm

43
00:01:35,775 --> 00:01:37,480
and that's how we get the cough reflex

44
00:01:37,480 --> 00:01:38,976
to bring the phlegm out.

45
00:01:39,054 --> 00:01:41,216
Now keep in mind, I
said this is the body's

46
00:01:41,216 --> 00:01:42,468
first line of defense.

47
00:01:42,468 --> 00:01:44,734
So these are good things to have,

48
00:01:44,734 --> 00:01:47,039
you want the body to do this.

49
00:01:47,039 --> 00:01:48,995
So chronic bronchitis is basically

50
00:01:48,995 --> 00:01:50,804
too much of a good thing.

51
00:01:50,804 --> 00:01:54,060
So we have over production of mucous,

52
00:01:54,060 --> 00:01:56,689
such that the body cannot clear it

53
00:01:56,689 --> 00:01:58,985
too much of a good thing,

54
00:01:58,985 --> 00:02:01,577
that's when we have chronic bronchitis.

55
00:02:01,577 --> 00:02:05,072
And of course itis just
means it's being irritated,

56
00:02:05,072 --> 00:02:07,142
and bronch refers to the lungs.

57
00:02:07,142 --> 00:02:10,789
So chronic inflammation and
irritation of the lungs.

58
00:02:10,789 --> 00:02:13,089
Alrighty, let's draw some airway.

59
00:02:13,089 --> 00:02:15,036
So we have our trachea,

60
00:02:15,036 --> 00:02:20,036
the big stem bronchus branch
off into their branches.

61
00:02:20,299 --> 00:02:22,475
Here you go, just keep going.

62
00:02:22,475 --> 00:02:24,953
There are 20 or 30 branches to this,

63
00:02:24,953 --> 00:02:25,496
you get the idea,

64
00:02:25,496 --> 00:02:27,696
they keep getting smaller and smaller.

65
00:02:27,696 --> 00:02:29,608
It's how our lungs expand.

66
00:02:29,608 --> 00:02:33,342
And as you know oxygen goes into our lungs

67
00:02:33,342 --> 00:02:36,950
and carbon dioxide from the body gets out.

68
00:02:36,950 --> 00:02:39,053
So you have irritants in there

69
00:02:39,053 --> 00:02:42,041
flooding what is usually a clear path,

70
00:02:42,041 --> 00:02:43,509
then the lungs are not going to like that.

71
00:02:43,509 --> 00:02:46,640
One of the most common chronic irritants

72
00:02:46,640 --> 00:02:48,277
that we have in our lungs

73
00:02:48,277 --> 00:02:50,229
is of course cigarette smoking.

74
00:02:50,229 --> 00:02:53,248
So, here we go, we're going
to light this cigarette.

75
00:02:53,248 --> 00:02:58,206
And where you see a smoke
rising from the cigarette

76
00:02:58,206 --> 00:03:00,078
is actually billions and
billions of particles

77
00:03:00,078 --> 00:03:02,668
that can enter and lodge into our lungs.

78
00:03:02,668 --> 00:03:06,820
As a response the glands
in the side of the walls,

79
00:03:06,820 --> 00:03:08,700
they start secreting the mucous.

80
00:03:08,700 --> 00:03:11,310
Remember it's part of our normal response

81
00:03:11,310 --> 00:03:12,752
to irritation.

82
00:03:12,752 --> 00:03:13,861
But of course chronics,

83
00:03:13,861 --> 00:03:16,333
we're talking about years
and years of constant.

84
00:03:16,333 --> 00:03:18,317
Everyday it's like this.

85
00:03:18,317 --> 00:03:20,714
Now eventually, what's
suppose to be a clear pathway

86
00:03:20,714 --> 00:03:23,332
becomes convoluted with the mucous.

87
00:03:23,332 --> 00:03:26,963
It's like, if you're drinking
through a straw from a cup,

88
00:03:26,963 --> 00:03:29,688
instead of having a clear straw,

89
00:03:29,688 --> 00:03:32,128
you're sucking on a milkshake.

90
00:03:32,128 --> 00:03:36,085
So this milkshake is thick
and it's clogging the straw.

91
00:03:36,085 --> 00:03:37,202
So you'll have to suck harder

92
00:03:37,202 --> 00:03:39,242
and work harder to get through.

93
00:03:39,242 --> 00:03:40,827
Likewise, with the mucous,

94
00:03:40,827 --> 00:03:42,910
sometimes there's so much build up

95
00:03:42,910 --> 00:03:46,962
that it can clog off one
little branch of the lungs.

96
00:03:46,962 --> 00:03:49,291
So no more gas exchange
can take place here

97
00:03:49,291 --> 00:03:52,106
and depending on the
severity of the disease

98
00:03:52,106 --> 00:03:54,570
you can have different areas of the lungs

99
00:03:54,570 --> 00:03:56,778
being out of commission
because of the mucous.

100
00:03:56,778 --> 00:03:58,850
Now of course we always
talk about smoking,

101
00:03:58,850 --> 00:04:00,337
but there are other things

102
00:04:00,337 --> 00:04:02,012
that can lead to chronic bronchitis.

103
00:04:02,012 --> 00:04:04,444
One important thing is pollution.

104
00:04:04,444 --> 00:04:06,868
Again pollutants are also billions

105
00:04:06,868 --> 00:04:09,573
of particles in the air all the time.

106
00:04:09,573 --> 00:04:12,115
In some countries that's
especially a big problem

107
00:04:12,115 --> 00:04:14,640
and chronic bronchitis
is very common there.

108
00:04:14,640 --> 00:04:16,154
Or we can have coal dust,

109
00:04:16,154 --> 00:04:18,060
for people who work in coal mines,

110
00:04:18,060 --> 00:04:21,037
or people who work with asbestos.

111
00:04:21,037 --> 00:04:22,955
Shipyard workers.

112
00:04:22,955 --> 00:04:25,618
The common theme here is

113
00:04:25,618 --> 00:04:27,721
it happens when we can inhale irritant

114
00:04:27,721 --> 00:04:29,635
and it happens everyday.

115
00:04:29,635 --> 00:04:31,241
Now if I just smoke for a few days

116
00:04:31,241 --> 00:04:32,265
and I have a lot of mucous,

117
00:04:32,265 --> 00:04:35,409
that doesn't qualify me for
having chronic bronchitis.

118
00:04:35,409 --> 00:04:38,393
The pathophysiology here talks about

119
00:04:38,393 --> 00:04:40,689
the overgrowth of the glands.

120
00:04:40,689 --> 00:04:42,977
So we actually look for tissue change.

121
00:04:42,977 --> 00:04:45,950
Now in a patient, to
diagnose chronic bronchitis

122
00:04:45,950 --> 00:04:47,913
is usually a clinical diagnosis,

123
00:04:47,913 --> 00:04:49,251
which means there are no test,

124
00:04:49,251 --> 00:04:51,663
it's just from the story.

125
00:04:51,663 --> 00:04:53,447
But we know from examining lungs of people

126
00:04:53,447 --> 00:04:54,783
who have passed away,

127
00:04:54,783 --> 00:04:56,866
the tissue change actually happens.

128
00:04:56,866 --> 00:04:59,130
So I just blew up one
branch of the airway here.

129
00:04:59,130 --> 00:05:01,100
We'll call this the lumen.

130
00:05:01,100 --> 00:05:02,876
The lumen just means
the inside of the tube.

131
00:05:02,876 --> 00:05:04,731
So the lumen is here,

132
00:05:04,731 --> 00:05:06,571
where the air is getting through.

133
00:05:06,571 --> 00:05:09,003
So the black space on both sides

134
00:05:09,003 --> 00:05:11,867
are the walls of the bronchi.

135
00:05:11,867 --> 00:05:15,484
So basically if we take a
cross section of our airway,

136
00:05:15,484 --> 00:05:18,971
in the middle here is the lumen.

137
00:05:18,971 --> 00:05:20,561
And right now I'm going to talk about

138
00:05:20,561 --> 00:05:23,473
the wall space of the bronchi.

139
00:05:23,473 --> 00:05:26,533
Okay so we have some smooth muscle

140
00:05:26,533 --> 00:05:28,797
around the walls.

141
00:05:28,797 --> 00:05:30,812
Again this spasm in this

142
00:05:30,812 --> 00:05:32,801
is what gives us the cough reflex.

143
00:05:32,801 --> 00:05:35,593
And right near the
surface close to the lumen

144
00:05:35,593 --> 00:05:39,338
we have these layers of glands.

145
00:05:39,338 --> 00:05:41,034
They're responsible for
the mucous production

146
00:05:41,034 --> 00:05:42,291
we've been talking about.

147
00:05:42,291 --> 00:05:45,107
As you can see they are
right under the surface.

148
00:05:45,107 --> 00:05:49,042
The job is to secrete
things into the lumen.

149
00:05:49,042 --> 00:05:50,122
Okay just for completeness

150
00:05:50,122 --> 00:05:53,090
let me draw some irritants in the lumen.

151
00:05:53,090 --> 00:05:54,311
Okay.

152
00:05:54,311 --> 00:05:58,151
So that's what a normal
wall usually looks like.

153
00:05:58,866 --> 00:06:01,334
There is a way for us
to put a number on this.

154
00:06:01,334 --> 00:06:02,695
And we only do this,

155
00:06:02,695 --> 00:06:06,405
we've only seen this in
people who have passed away

156
00:06:06,405 --> 00:06:08,141
and their lungs get caught up in the lab,

157
00:06:08,141 --> 00:06:09,542
and we can look under the microscope

158
00:06:09,542 --> 00:06:11,747
to see the Reid index.

159
00:06:11,747 --> 00:06:14,556
Which is a way to calculate
the ratio of the glands,

160
00:06:14,556 --> 00:06:17,546
the thickness of the
glands to the whole wall.

161
00:06:17,546 --> 00:06:21,859
Now normal Reid index is less than 40%.

162
00:06:21,859 --> 00:06:23,950
So we can see the thickness here

163
00:06:23,950 --> 00:06:26,781
versus the thickness of this whole wall.

164
00:06:26,781 --> 00:06:29,570
It should be less than 40% in you or me.

165
00:06:29,570 --> 00:06:30,630
And of course in the middle here

166
00:06:30,630 --> 00:06:31,958
there are other things like cartilage

167
00:06:31,958 --> 00:06:33,741
or connective tissue.

168
00:06:33,741 --> 00:06:35,502
We're just going to
fill it in a little bit.

169
00:06:36,587 --> 00:06:38,884
Now what happens in chronic bronchitis is,

170
00:06:38,884 --> 00:06:43,442
the actual thickness of
the gland layer grows.

171
00:06:43,442 --> 00:06:47,041
So the glands start proliferating,

172
00:06:47,041 --> 00:06:49,656
because we need so much mucous

173
00:06:49,656 --> 00:06:51,800
that the original number is not enough,

174
00:06:51,800 --> 00:06:54,220
so the body is recruited
to make more glands

175
00:06:54,220 --> 00:06:58,277
and they extend towards the smooth muscle.

176
00:06:58,277 --> 00:07:00,341
So in chronic bronchitis,

177
00:07:00,341 --> 00:07:03,756
the Reid index is usually over 50%.

178
00:07:03,756 --> 00:07:06,154
So definitely more than
half of the thickness

179
00:07:06,154 --> 00:07:08,913
of the whole wall is made of glands.

180
00:07:08,913 --> 00:07:11,214
Now remember we cannot
do this in living people

181
00:07:11,214 --> 00:07:14,094
because we have to cut away their lungs.

182
00:07:14,094 --> 00:07:17,118
So just a way for us to put
a number on this disease,

183
00:07:17,118 --> 00:07:19,079
but usually the patients are diagnosed

184
00:07:19,079 --> 00:07:21,537
and treated according to their symptoms.

185
00:07:21,537 --> 00:07:23,822
And the symptoms all come
from this tissue change

186
00:07:23,822 --> 00:07:26,811
and the over production of mucous.