and as you go through here, get a nice little
overview, don’t you, of your infections and diseases.
Let's continue forward. As you move forward
and get into our respiratory zone, and as
we move forward here, you have less cilia.
That is not necessary because now the conducting
zone, hopefully has done its job properly
as it gotten rid of those antigens and such
and gone it is, but now, down here, we start
getting our true air and as we go through
this, I would like to point out a
few things physiologically. You have
heard of dead space, haven’t you? Yes. Well,
dead space, what does that mean to you? It
means that it is air that is getting into
the divisions or the bronchial tree and however,
it does'nt participate in gas exchange. Now,
we will only talk about dead space where it
is relevant to us in pathology, but it is
imperative that from physiology that you have
understood the definition of dead space. For
example, if it is anatomical dead space, there
are anatomical holes, I
shouldn’t say holes, but there
are anatomical existence or anatomical type
of crevices that exist in which it accumulates
the air as one is breathing in. But, guess
what? That air that gets anatomically trapped,
maybe up in the respiratory zone, will not
participate in gas exchange because it does
not make it into the alveoli. So, what I wish
for you to do is clearly see the picture of
an alveolar sac, air coming in, but then,
it gets trapped anatomically. You don’t
have to know exactly where those spots are.
Well, if it gets trapped, guess what? That
air is not going to participate in gas exchange
because it didn’t make it down into the
alveoli. Now, something else that we will do,
as we move forward, very much go through
our alveolar gas formula. It's important
that you understand what is known as A-A gradient
clinically, as we move forward.
Now, the last little portion here distally,
we will go into more detail and a couple of
things that I wish to point out here that
students tend to get confused, but you will
be clear after our discussion. Infections,
in blue, once again.
First, I would like to point out number 4
which is your typical pneumonia and by typical
pneumonia, yes, there is going to productive
cough. There is going to be quite a bit of
fever and that productive cough is then going
to show you maybe different types of sputum.
May be it's rust colored and by that,
we mean that there is blood-tinged type of
sputum. Maybe it's yellow or golden, that
to you, may be, indicates staph aureus. Maybe
it's green and we talked about pseudomonas
and pyocyanine, get my point. Or maybe it's
mucoid, very mucoid and what
was the type of pneumonia that is quite
common in elderly and also in alcoholics?
That was Klebsiella pneumonia. So, keep that
in mind as we go through typical pneumonia
in which the fevers are quite high. You expect
the sputum to be quite productive. Isn’t
that typical? Of course, it is and then maybe
perhaps you bring in issues such as lobar
consolidation or broncho. Both of those
will be typical. Is that clear? Now, you will
notice with number 4 and I wish to point out
this to you, otherwise you might get confused.
This will be involvement of the alveoli. So
therefore, the type of sputum that you are
going to then aspirate is going to be alveolar,
isn’t it? The alveolar type of sputum so
that you can definitely
be able to culture that organism versus number
Number 3 in blue here represents a pneumonia,
but this is atypical pneumonia. What does
that mean? Take a look at the name here. The
description is interstitial organisms. Understand
the significance of that. Is the interstitium
the alveoli? No. The interstitium,
it’s outside the alveoli by definition.
So, what is the most common type of organism
that is going to cause disease of the interstitium
but most likely would spare your alveoli?
Good. Mycoplasma pneumonia. It's the most common
type of atypical pneumonia. Why do we say
That number 3 represents pneumonia of the
interstitium, not the alveoli. It is outside
of it. Number 1.
Number 2, we say atypical because the patient’s
fever is not going to be high. It will be
a low-grade fever. Is that understood?
Number 3, on chest x-ray, if we have
interstitium of the lung that's affected, do
you think that you might find markings on
x-ray, chest x-ray? Sure, you will. So, this
is called what on chest x-ray? Reticuloid
nodules or reticular pattern.
What does reticular mean? It means mesh work.
So literally interstitial, you are going to
find all this mesh work. So therefore, the
chest x-ray and its findings is going to be
far worse than what the actual patient is
feeling. We call this what kind of pneumonia?
Atypical. Now, if the same type of chest x-ray
or image, instead of an x-ray, you were doing
a CT. On CT, well that reticular pattern
that you would refer to is now called what?
Ground glass, type appearance. Think about
what ground glass looks like? It looks rather
opaque-ish, doesn’t it? What is this? Atypical
pneumonia. We will be spending time with this.
There is number 3 and number 4. Make sure
you understand the significance of typical,
number 4. Number 3, atypical. Remember the
Here, way down in the distal portion, what
zone are we in now? The respiratory zone.
Involvement in gas exchange. Emphysema. With
emphysema, there will be a lot to talk about.
Here once again, I recommend that you go
back and take a look at pulmonary physiology
so that you are completely clear about what
sea level ambient air is in terms of pressure,
barometric is 760 mmHg. When you get this air
into the trachea, it is going to then get
humidified. That value is 47. Are we clear?
So, 760 minus 47, then what do you do? Anywhere
that you are on planet Earth, I don’t care
if it is sea level and I don’t care if you
are at Mount Everest, the oxygen concentration,
your fractional oxygen on planet earth is
how much? 0.21. Now, for simplicity purposes,
say that you have taken an exam, taken your
boards and what not. Then you can use 0,
you will be perfectly fine. What is 0.2 mean
to you in terms of percentage? It means 20%.
I said planet Earth. What about planet hospital?
Well, planet hospital depends. So in a hospital,
they can change it, because we as human beings,
love to manipulate things. And so therefore,
you are manipulating the oxygen that you are
receiving and instead of 20% or may be your
patient requires 40%, requires maybe even
100%. So, please do not use 0, maybe use
0.4 representing 40% or 100% would be 1.0.
Are we clear?
I am just going to take as far as that right
now, but as I said, this is all learnt in
physiology. It would behoove you to make sure
that you are comfortable with the material
before moving in, especially when I start
getting into A-A gradient. That's the second
time, that I have made such a reference. Now,
we have adenocarcinoma here, number 5.
Now, adenocarcinoma is rather interesting.
First and foremost, does'nt have to be a
non-smoker. And its preponderance could also
be found in females, scary. Number 1 since
1980's in the United States as being the number
1 lung cancer. Is squamous and small up there?
They are up there, but understand, number
1 is adenocarcinoma. So, we will walk through
adenocarcinoma in great detail. Don’t you
Next, adenocarcinoma, also on chest x-ray,
becomes important to us because we then refer
to this being peripheral. All these come under
what kind of lung cancer? Bronchogenic type
of lung cancer. Obviously, we did not refer
to a bronchial carcinoid because that is non-bronchogenic
and we do not refer to a mesothelioma because
that is non-bronchogeneic.
Okay, definition of dyspnoea. What does dyspnoea
mean to you? It means shortness of breath.