Welcome to Pulmonology. Our approach in this
lecture series will be the patient walk in
through that door with signs and symptoms.
The patient walks in with cough. History of
that cough, was it a dry cough? Was it productive?
In terms of productive, what color was it?
Was it stained as being brown? Was it rusty?
Was it yellow? Was it green? Signs and symptoms
is how you need to approach pulmonology here
so that you have a bird’s eye view of what
is going on with pathophysiology for each
of the diseases and infections that we shall
cover. We will walk through restrictive and
obstructive diseases, but prior to any of
that, let's first take a look at signs and
Overview of our bronchial tree. We begin at
the proximal region with the trachea. And
then as we divide into branches
or divisions, by the time you get all the
way down to the alveoli distally, well you
can imagine as to how thin that alveoli is,
right? What about that trachea? The trachea
is a supportive structure. It is basically
an air tube. That is exactly what it is. Meaning
to say that it is then going to take the air
that is coming down from the ambient air which
at sea level is what please? Good, 760 mm
at sea level and you need to make sure that,
that trachea is nice and strong. So therefore,
it is made up of cartilage or cartilaginous
rings. And then also, in the upper portion
or the proximal portion of our respiratory
tree, then we must have a method by which
we defend ourselves against that ambient air.
Think about ambient air. There is a lot of
stuff in there. It has antigens, it has allergens
so on and so forth. So, we need to make sure
that we keep things like that out and so
therefore think about the histology here
as we branch deeper down into the alveoli.
That is important for you to understand and
keep in mind, I don’t want you to just take
a look at this and read what is on the Y-axis
or on the vertical, parallel words here. I
am just giving you an overview and things
that you already know about, but what you
are also bringing into play is what is the
function of the trachea? What kind of cells
does it have? It has mucociliary clearance,
thus it has to be columnar cells. It has to
be ciliated and the mucociliary clearance
helps you take out any unwanted particles
that you are breathing in and you have to
have mucous, right, at the proximal portion.
And then as you go further distally, do
you have cilia done in the alveoli? Of course
you don’t. Why is the alveoli so thin? Type
1, type 2 pneumocytes are present. We know
that it's squamous like. It has to be very
thin. Because what's across that alveoli membrane,
please? Exactly. It is the pulmonary capillaries
responsible for quite a bit of gas exchange.
Why would you want large columnar cells down
there? What does that mean to you pathologically?
Now, what we shall do moving forward, please
understand, is that we are going to plug in
our infections into this respiratory tree.
We are going to add in some diseases. For
example, we will put in the most common lung
cancer, adenocarcinoma, isn’t it? It is.
Adenocarcinoma is the most common, but Dr.
Raj, I thought that smoking was heavily
associated with small cell lung cancer. That
it is. Or squamous cell cancer, that it is.
However, what if you are a non-smoker and
could you still develop lung cancer? Sure,
In the United States, it is the number one
killer in both men and women, lung cancer
is in terms of mortality. So therefore, we
will have to know everything about bronchogenic
adenocarcinoma. So, as we go through here,
all we are doing here is setting up a nice
little tree here and as we have in the proximal
portion, these are cartilaginous and as we
move further down into the bronchiole, alveolar
duct and then in the alveoli. The upper
portion is known as the conducting zone. That
is an important description that you need
to know. Remember all this from anatomy and
physiology, right? And the conducting zone
literally is conducting air from the outside
world down into the trachea. And then as we
move distally beyond the alveolar duct, then
you get into the respiratory zone, makes perfect
What is the respiratory zone responsible for?
Gas exchange. Hence, the name respiratory.
Let's take a look.