Pulmonary Clinical Anatomy: Introduction

00:02 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 symptoms.

00:47 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.

02:42 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.

03:05 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.

03:27 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.

03:37 However, what if you are a non-smoker and could you still develop lung cancer? Sure, you could.

03:44 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 sense.

04:32 What is the respiratory zone responsible for? Gas exchange. Hence, the name respiratory.

04:39 Let's take a look.