Breathing Basics

What is "pulmonary medicine"?

Pulmonary medicine is a specialty within internal medicine that focuses on the lungs and helps you find and understand methodologies for evaluation and then making a proper diagnosis. Making a proper diagnosis is extremely important, followed by that is the correct management. All of the systems; the evaluation, the diagnosis, and the management are constantly upgrading. We find new cures, we find new diseases, we find new methods for diagnosis, and that becomes really exciting. However, there are other aspects of pulmonary medicine that are applicable. For instance, we do most of the work that occurs in Intensive Care Units, so that if a person comes in and is critically ill, whether it's lung, or heart, or kidney or liver, they usually encounter a pulmonologist first in the ICU, who has been trained as an intensiveist. We also deal with sleep disorder breathing, so that most of the sleep centers where the diagnosis of sleep apnea etcetcera is made are run by pulmonologists. Then there's another area that's extremely important for pulmonary medicine and that's the hyperbaric chambers where we apply pressure and oxygen to the treatment of a lot of disorders. Not just carbon monoxide poisoning, air embolism, nitrogen embolisms, and accidents that occur to people who do diving, but also the application of technologies for wound healing, and that usually falls into the area of a pulmonologist.

How is a pulmonologist different from other doctors?

A pulmonologist differs from other doctros in that they must first be trained in internal medicine and then will be able to branch into solely treatment of the lungs. A pulmonologist must know a lot about other organs. A nephrologist is trained in kidney treatment, but although kidney doctors focus just on kidney disorders, they are aware of other organs. Our systems in medicine now, have become so sophisticated that it's impossible to learn all the information that you have to know just for one speciality or even two. Medical care has been divided up so the cardiologist takes care of the heart, the pulmonologist the lungs and the neurologist the brain. So doctors are different in the respect that they diagnose and treat different organs.

What is "respiration"?

Respiration is the exchange between oxygen and CO2 in the body. However, it's important to know that it occurs on two levels. There's macro respiration which is when you breath in air which is a little less than 21% oxygen, and then you extract about 4% of that down to about 16%. And when it comes out it contains a lot of CO2. On the cellular level there's respiration that goes on where the oxygen is burned in the process of metabolism, and in burning you've got to have three things: oxygen, fuel, and in the case of the body, glucose and certain fatty acids. You also have to have heat and in exchange for that, you have to have fuel. But when the body's smoke is CO2, and the smoke builds up, it kills you. So respiration serves not only to extract oxygen, but to eliminate CO2. The respiration that occurs at the cellular level has to match the macro level, it is involved in those two aspects.

What is the "respiratory system"?

The respiratory system is the part of the body that deals with the exchange of oxygen and CO2. It starts off with the nose. It goes back to the nasal cavity, down through the sinuses, turns the corner, goes down through the pharynx, behind the tongue, to the voice box, into the trachea, and then to the right and left main stem bronchi where the divisions go to the right and left lung, down through smaller and smaller tubes, if you will, to where it gets to the alveoli which are little tiny sacs. There are about three million of them in a normal lung, and that's where exchanging oxygen with CO2 takes place. You may like to think of the lower portion of the respiratory tree as like a real tree, only turned upside down, with the trunk being the trachea. Then branches, until you get way out to the end and there you have the little fine twigs, which are the bronchioles. And then they divide into conducting airways and then, finally, to the alveoli which might, in that analogy, be the leaves of the tree.

What body parts compose the upper respiratory tract?

The upper respiratory tract is composed of the nose, nasal cavity and sinuses. There are the frontal sinuses, maxillary sinuses, and sinuses back by the ears. Those sinuses are part of the respiratory tree, which then goes back to the pharynx, down to the larynx (the voice box) and that's the upper part of the respiratory tree.

What body parts compose the lower respiratory tract?

Once you cross into the chest cavity or just below the voice box, right here where the notches for your vocal cords, then it hits down into the trachea right and left main next to the bronchi. That then divides off down into the alveoli thats the lower tree.

How do humans breathe?

Humans breathe by using muscles of inspiration. The diaphragm, which is dome shaped, will contract, flatten out, and then essentially invert itself, and in the process will suck air into the lungs. There are no muscles of expiration, so the lung, being an elastic organ will much like a balloon that's been blown up, will just let go of the neck of the balloon and it will empty. That's pretty much how the lung empties. There are some people who believe that when you breathe, the right nostril is a direct tube going to the right lung, and the left nostril is directly connected to the left lung, so that if you were to obstruct the right nostril, you would eliminate your ability to breathe through the right lung, and vice versa, with the left nostril. That's not the case. It is a matter of both nostrils empty into a large area behind the tongue, it goes down through the vocal cords, and it isn't until it gets to the end of the trachea, right and left, that you then have a split between the airflow.

How does air get into the lungs?

The lung is pulled in by negative pressure. As the diaphragm contracts, it sucks the air in and it moves all the way out to the ends of the air passages through the bronchi and the bronchial's. What's important to know is that it's important to take periodic deep breaths to stretch everything out and get that air all the way out. And if you don't do it, then the body has a way of taking a deep sigh every once in a while. We really don't have control over that. We can do one ourself, but periodically the body kicks in with one just for our own benefit.

What is the difference between the nasal cavity and the sinuses?

The nasal cavity is where the nose heads back toward the back of the throat, and the sinuses are off to the side. They do various functions like: help to humidify the air, and they give some resonance to your voice. They are not part of the nasal cavity other than they do drain into it but they have different structures. They have different mucosal linings, and they are specialized, whereas the nasal cavity itself is just a conduit, an open vestibule if you will, to take the air from the nose all the way to the back of the throat and down into the trachea.

What are "bronchi"?

Bronchi are tubes that start at the end of the trachea, so you have the right and left main stem bronchi. And then they divide into smaller and smaller bronchi as they reach the periphery of the lung. Bronchi are amazing. They have a lining called "mucosa," which secretes a lot of different compounds. They have little, fine cilia on them to help move mucous up to help cleanse the lung. Then under the mucosa is a series of muscles and cartilage that allow for the airways to contract and dilate as they need to contract and dilate, given whatever circumstances.

What are "alveoli"?

The alveoli are the little sacs out on the end, and you need to visualize this paper thin, very fine little sac that has capillaries around it that the red blood cells flow around in a constant monolayer around the alveolar sac so that these red blood cells are maximally exposed to the oxygen that's available in the alveolus, and are capable of, with the blood flow and the red blood cells, getting rid of the CO2 and then come back together again on the other side, transporting it back into another system that carries the blood back to the left side of the heart and then out to the rest of the body. There are probably about three hundred million alveolar sacs in the lungs and if you visualize a football field, that package inside your chest in these alveoli are enough alveoli to give you a surface area that would extend from the goal line out to about thirty yards when you lay that out as a monolayer. And it's an amazing bit of packaging that goes on inside our lungs that allow not only the blood to flow through but also for that much surface area to be available for these little alveoli.

How often do I breathe?

Most people breathe between 12-20 breaths per minute and in the pediatric groupand infant groups it's much faster than that. However, as we get older things slow down. Not only other things in our body, but our breathing slows down. But, under resting steady state, about 12-20 breaths per minute.