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Pulmonologist Dr. Ravi Kalhan, MD answers the internet's burning questions about our lungs. Why do we yawn and why is it contagious? How do lungs heal after a smoker quits? What chemicals actually make vaping dangerous? How does a lung transplant work? Answers to these questions and many more await on Lung Support.
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00:00I'm Dr. Ravi Kalhan, pulmonologist at Northwestern Medicine. I'm here today
00:04to answer your questions from the internet. This is Lung Support.
00:12A Reddit user asks, why are we able to breathe both consciously and automatically? This is super
00:18interesting and unique to the lungs because no other organ can you consciously control it. You
00:28can't really just make your heart start beating faster. You can't make digestion speed up. There's
00:33no other organ that can do this. But for the lungs, it's essential. So the brainstem, the oldest part
00:40of the brain in terms of evolutionary terms, controls breathing automatically. And respiration
00:46just happens. The brainstem makes sure that the diaphragm keeps contracting, the lungs keep filling
00:53with air, and you keep breathing. That's super important because otherwise every time you went
00:56to sleep, you die, right? But we also need to talk and laugh and scream and sing. So the conscious
01:04part of the brain, the cortex, can actually control breathing in addition to the brainstem. So in that
01:11sense, we can both manually control our breathing as well as have automatic functions that keep us
01:17alive. Purist Videos asks, how exactly do asthma inhalers work? Well, asthma inhalers contain medicine.
01:24It actually drives me crazy when people only refer to it as an inhaler because it's a medication and
01:31they're medicines that we can deliver straight to the windpipes. The problem in asthma is the windpipes
01:36are over-inflamed because a person is susceptible to things in the environment like pollen, pollution,
01:44or if someone smokes cigarettes, that cause inflammation in the windpipes. So the way we treat that
01:51is with inhaled anti-inflammatory medicine. Usually that's inhaled steroids. You can inhale
02:00corticosteroids that treat the surface of the windpipes so that they get less inflammation because of
02:08those corticosteroids anti-inflammatory effects. And then the lungs don't have that inflammation and
02:14people have less asthma symptoms. Asthma inhalers also often have a bronchodilator. Those medicines
02:20relax the muscle surrounding the windpipe so that the windpipe can open up and air can move in and
02:27out more efficiently. EyeisSmarter asks, what actually happens when you get the wind knocked out of you?
02:33Well, when the wind gets knocked out of you, it usually comes after someone gets hit in the chest or
02:37punched in the gut. And that's not actually a problem of the lungs. It's a problem of the diaphragm
02:43where getting hit right here, sort of like where the ribs come together, there's a nerve bundle right
02:50there called the solar plexus, which is not that protected by bones. It's like right in that open
02:55space behind your stomach. And when you get hit there, the thought behind the wind getting knocked
03:00out of you is the diaphragm goes into spasm. So the diaphragm doesn't work right. You feel like you
03:06can't breathe because the diaphragm is not moving down. And then it takes like 30 seconds for
03:10everything to reset, calm down the diaphragm to relax and for the person to recover after getting
03:15the wind knocked out of them. One user asks, why do humans have two lungs instead of one single
03:20big lung? It's probably the result of evolution deciding to having two things or redundancy is
03:27better than having one thing. It's like, why does an airplane have two engines instead of one? Well,
03:32that's because if one goes down, the other still works. Akide asks, does this sound
03:36like COPD? This doesn't sound like COPD because COPD usually is characterized by having less sound
03:47in your chest. COPD stands for chronic obstructive pulmonary disease. It also gets called emphysema.
03:55So normally the lung is like rubbery and elastic, like a balloon. And if you blow air into it
04:03and it's inflated, you take a big breath in and let it go, the air just comes out super fast.
04:09When someone has emphysema, the lung is not rubbery anymore like a balloon. It's like a plastic grocery
04:15bag. You blow air into it and the air just kind of sits there and floats and the air doesn't
04:21come out.
04:22And we normally hear less sounds in the lung, not more sounds in the lung.
04:26With a bag asks, how TF does a lung transplant work? Like how do they get the lungs out? In
04:31the
04:31old days, we actually used to just take the lungs out by creating a giant incision in the chest,
04:38opening it up, deflating the lungs and taking them out. When they deflate, they're actually pretty
04:43small, like the size of your fist. So these days, there's all kinds of new ways that they're doing
04:50transplants that make it easier to tolerate the surgery. So the lung only actually has three
04:57connections to the body. They're connected through a windpipe, through a vein, which takes blood from
05:02the lungs to the heart and an artery, which brings blood from the heart to the lungs. Just those three
05:07hookups. So if you can remove those three hookups and deflate the lung, you can actually take it out
05:12through a smaller incision. So that's what's going on now at a lot of places that they're doing smaller
05:18incisions, sort of between ribs, where they can take the lung out and then put a new lung in.
05:24The way people live during that period is they're put on a bypass machine, which does the oxygen and
05:29gas exchange for the person while their lungs are going in and out of the body. But the manner in
05:35which the transplant takes place at a lot of places is a lot less sort of dramatic, what we used
05:41to call
05:41a clamshell, sort of just cut open and lift up the chest. Now there are a lot of smaller ways
05:47to do it
05:47because the lungs can deflate and re-inflate once they're in the body. AndreTheBoss21 asks,
05:53did you know that we still don't know why we yawn and why it's contagious even across species?
05:59There are some theories about why people yawn. One of them is debunked, that the brain or the body
06:04needs more oxygen. That's not why people yawn. The current most talked about theory is people yawn
06:11because it increases blood flow to the brain and cools it down. So it's like a cooling function
06:18for the brain. Why the brain needs cooling, I don't think we know. Why yawning is contagious,
06:24some people think is like an old social network thing of empathy that gets transmitted sort of
06:31naturally in the human state. Because yawning is considered sort of this empathetic social response
06:37to people around them. It takes time to develop that empathy. And four and five-year-olds in general
06:44don't have contagious yawning because they haven't developed those empathetic networks or so the
06:49theory goes. A Reddit user asks, how does air enter the lungs? Well, this is an interesting question
06:54because while one might think air gets sucked into the lungs, it's actually a completely passive
07:00process. There's a muscle below the lungs called the diaphragm, which is dome-shaped. When you breathe in,
07:06that dome flattens and the lungs have negative pressure in them compared to what's in the
07:13atmosphere. Air always flows from higher pressure areas to lower pressure areas. So when the dome
07:19flattens and there's negative pressure inside the chest, air enters the chest. How does air leave the
07:26chest then? Well, the lungs always want to deflate. They're filled with air and they're like a rubbery
07:32balloon. So after that negative pressure fills the lungs, the diaphragm relaxes and air's natural
07:38tendency is to come out because the lungs are elastic and rubbery. Trollgirl666 asks,
07:44WTF or hiccups for like, why am I being punished for breathing? Well, a hiccup is a pretty weird thing.
07:51It is when the diaphragm tries to breathe, but then the vocal cords prevent the breath from happening.
08:00And there's like this awkward feeling of where air is trying to go in, but then it gets cut off
08:04up here by the vocal cords. And no one knows why they happen. They could be because something
08:10irritates the diaphragm. They could be because something irritates the vocal cords. Like sometimes
08:14people say they drank too much carbonation and they start hiccuping. There's no real knowledge for
08:19why that reflex exists. It's probably related to some ancient reflex that developed over time during
08:25evolution, but they certainly are uncomfortable. Birkin8000 asks, what chemicals actually make
08:31vaping dangerous? There are a lot of chemicals in vape juice that we don't know all the time how
08:37dangerous they are, but it stands to reason that they probably are. The first big one is if someone's
08:42vaping nicotine, there's nicotine in the vape juice. At high levels, actually, it gets heated up
08:47in the juice and aerosolized, and then you can breathe it in. And that's a high concentration of
08:53nicotine, which creates addiction. Nicotine is a highly addictive chemical. How dangerous that
08:59nicotine is on a day-over-day basis is not totally clear, but being addicted to it creates problems and
09:07desire for more and more nicotine. There are other chemicals in vape juice that get heated up. For
09:13example, there's formaldehyde. The stuff used to preserve bodies is in vape juice. And heating that up
09:20and inhaling it, well, that probably isn't that good for you in the long run. There are other things
09:25like there's flavors, and these are food-safe flavors in vape juice. So tutti-frutti-flavored vape or
09:32peppermint or whatever the vape is. They're probably okay to eat, but we don't know what happens when you
09:37heat them up, turn them into a volatile substance, and inhale it in the lungs. That could be really
09:44dangerous. So all these things, you know, are in my mind as a pulmonologist bad for you. I think as
09:52a
09:52lung doctor, the thing you're supposed to inhale is air. Gandhi's account asks, why does exhaling after
09:58you've held your breath for a long time feel like you're not suffocating? Well, when you hold your
10:02breath, you take a big breath in and hold your breath, you're not breathing. And when you're not
10:09breathing, the body does not release carbon dioxide. It also doesn't inhale oxygen, but in the sense of
10:16suffocating, the carbon dioxide is what matters. So when you don't exhale carbon dioxide, it builds up
10:24in your blood. Carbon dioxide is an acid, so the pH in your blood goes down. There are receptors
10:32in your bloodstream that feed into the brainstem and create a sense of needing to breathe when the pH
10:42in the blood goes down because of this increase in carbon dioxide. So that's when the brainstem
10:48kicks in and says, dude, we better breathe right now. So the sense of relief that comes when you
10:55finally start breathing and feel like you're not suffocating anymore is because you finally are
11:00releasing that carbon dioxide, the pH in the blood is going back to normal, and the satisfaction of
11:06being able to breathe again kicks in. RatayOBC asks, what's the difference between breathing in
11:12through your nose and mouth and why it's recommended to do it through your nose? When you breathe through
11:17your nose, a lot of good things happen. The nose filters air. There's hair in your nose. It's the first
11:23line of filtering. And then there's other filtering steps through what are called ciliated epithelia.
11:28There are cells in the entire respiratory tract that have little flapper things on it that can move
11:35debris and other mucus out of the way so that air can go through more smoothly. When you breathe
11:40through the nose, the air also gets warmed up and humidified. So that's good. And then the third
11:45thing, which people don't actually know that commonly, is the sinuses produce something called
11:51nitric oxide. Nitric oxide is what's called a vasodilator. And when nitric oxide comes into
11:57contact with the lungs, it helps ensure that where air goes, because there's nitric oxide there,
12:05the blood also goes because it opens up blood vessels. So then we have a really good matching
12:11between where the oxygen goes and where the blood goes. So oxygen can more efficiently enter the
12:17bloodstream. So those are all benefits of breathing through the nose. If you breathe through the mouth,
12:22those things don't happen. There's no humidifying. There's no clearance. There's no nitric oxide,
12:28but what there is, is less resistance to airflow. So when you're exercising and you need to get air
12:35in and out really efficiently, you shouldn't breathe through your nose. You should do the natural thing,
12:39which is breathe through your mouth. But when you're just at rest or not doing anything that
12:43involves exertion, there are clear advantages for why breathing through your nose is better.
12:54It's actually not your lungs. The lungs don't have pain receptors. The windpipes do, however. And when
13:00you exercise, you inhale mostly through your mouth. So all the good stuff that happens when you breathe
13:05through your nose, humidification of the air, warming of the air, cleaning of the air doesn't
13:10happen. And everything goes sort of straight in through the mouth. So if it's cold outside,
13:13this symptom might get worse because it irritates the windpipes when you breathe in cold air through
13:20your mouth. Google bra asks, coughing up mucus with blood. Should I be worried? I think you should
13:25be worried. Anyone who coughs up blood should see a doctor ASAP. Rachel bunny asks, why does breathing
13:31into a paper bag help with hyperventilating? One could wonder why someone hyperventilates in the first
13:37place. Well, it could be caused by lots of things. The biggest thing is anxiety or distress or panic.
13:43Those are the things that we treat with a paper bag. When someone hyperventilates,
13:47they have lowered the amount of carbon dioxide in their blood. It actually turns out that those
13:52people who are hyperventilating have normal oxygen levels. It's all an ability to lower their carbon
13:57dioxide when they start breathing really fast. So that makes you feel kind of funny and unsettled.
14:02Having a high pH creates a sense of further anxiety, maybe tingling in the fingertips, all sorts of
14:07weird things that go on when someone hyperventilates. If you start breathing into a bag, however,
14:11when you hyperventilate, the carbon dioxide you breathe out gets stored in the bag because you're
14:16sort of pinching it and breathing in the bag like this. So you start re-breathing carbon dioxide,
14:24which naturally makes the carbon dioxide level in the blood go up again. So the pH goes down,
14:30the blood becomes more acidic or gets closer to normal, and it relieves the sense that you get
14:36when you're hyperventilating that everything is going wrong. A Reddit user asks, what happens to
14:41food that accidentally gets in the lungs? The first thing that probably happens is you start coughing
14:46a ton because the body has a defense mechanism. If something that's not supposed to hit the vocal
14:51cords or the main windpipe up here, the trachea, if something hits that, there are very, very sensitive
14:57cough receptors there that make someone start coughing like crazy, and the food never makes it down further.
15:02If the food does make it down further, like a tiny amount of food gets down further,
15:07the body has defense mechanisms for that. One of the biggest defense mechanisms is that there are
15:12cells in the lungs that are called macrophages that will surround that thing and start to sort of
15:19degrade it or take it up so that it can't cause problems. Don't Spill Me asks, what is going on
15:25when a lung collapses? Normally, the lung stays inflated only because of a suction effect of
15:34the lung against the chest wall. There's just like a thin layer of fluid between the lung and the chest
15:40wall, and the lung is kind of just suspended there. You know, if you have a glass and it's condensing
15:46because you have ice cubes in it and it's on a counter, the glass kind of sticks to the counter
15:51because of that fluid between the glass and the counter, that's what's going on with the lung.
15:56It stays inflated because of that fluid. So if something disrupts that layer, or if the lung gets
16:03punctured for some reason, so there's now air between the lung and the chest wall instead of fluid,
16:10the lung will actually collapse because it can't stay inflated. The lung is rubbery and elastic.
16:15It's only staying there because of that suction effect. So when the lung collapses, the way to
16:20treat it is to insert something called a chest tube, where we stick a tube from the outside through
16:27between the ribs into that space between the lung and the chest wall and suck out the air that got
16:34in there or whatever else is in there. Sometimes an infection can occur in there. Sometimes blood can
16:38end up in there. Suck that out. So then the body can heal, restore that little fluid layer,
16:43and then the lung can stay inflated again. A Reddit user asks, how do the lungs heal after a
16:48smoker quits? This is a great question because I think every smoker should quit. And it's true that
16:53a lot of the lung can heal. Most of that healing happens in the windpipes, which are irritated by
16:59smoking cigarettes. So normally the lungs have a defense mechanism called the mucociliary escalator,
17:06which is the flapping of these things called cilia at the tops of the cells that line the windpipes.
17:13So when you breathe something in that's toxic, the cilia kind of can flap it back up. So if you
17:19inhale small particles from cigarette smoke, the cilia can help clear things out. Or if the lungs
17:24produce too much mucus because they're irritated, the cilia can kind of flop it back up to your mouth
17:29and you swallow it. And it goes to your stomach where it doesn't cause any harm. One of the biggest
17:33bad effects of cigarette smoking is that it impairs the function of this mucociliary escalator and
17:40actually causes the cilia to disappear. So there's no defense when someone smokes cigarettes. When
17:46they quit smoking, that function starts to return over a month or so. So a lot of people when they
17:52quit smoking say, oh my gosh, I quit smoking and I'm coughing up all this mucus now. Well, that's
17:56because the defense mechanisms that help you clear out mucus are actually working again. That's a
18:01positive sign. Bee Rooster Master asks, every time I cough, a little chunk of my lung comes up. Is this
18:06normal? Do lungs grow back? Well, it's pretty unlikely that that's actually a chunk of your
18:11lung coming up. It's pretty hard to cough up a chunk of lung. I don't think that actually happens.
18:16It's probably mucus that's coming up that looks pink, maybe because there's a little bit of blood
18:22in it, but it's not actually your lung. Fever Coach Admin asks, asthma versus pneumonia. How do lung
18:29sounds differ? Here's the sound of pneumonia. So in that clip, someone is talking or whispering
18:42while they have pneumonia. And when someone has consolidated pneumonia, pneumonia is when part of
18:48the lung fills up with infection or something else. So like on this x-ray, you can see the normal
18:54lung
18:54is dark and black and filled with air. And then there's this top part here, which is white, which
19:00means it's filled with something. When the lung consolidates, it can suddenly transmit sounds much
19:07better than if it's filled with air. So if the lung is filled with air and you whisper, and I
19:12listen
19:12with the stethoscope right on that spot, I won't hear you whispering. But if it gets consolidated or filled
19:18with fluid, suddenly it can conduct what is being said at the vocal cords. So if someone whispers,
19:26then you can actually hear the whispering as sort of a vibrating sound when you listen over that part
19:32of the lung. Now we can listen to what asthma sounds like. Asthma, in contrast, is a problem of the
19:40wind
19:40pipes, the pipes that lead to those air sacs. And in asthma, those wind pipes become narrowed. So they
19:48don't transmit air as well. So when someone has asthma, we hear air going in and out of the lungs
19:56in a much more prominent way than we do if someone doesn't have asthma. So we hear squeaking or wheezing
20:03or various things like that, that make noise of air going out of the lungs that we normally would not
20:09hear as a squeaking high-pitched noise. I Promise to Shut Up asks, how does oxygen go from lungs into
20:15blood?
20:16Could you explain in details and simply? Well, when you breathe in, oxygen enters the lungs and the
20:23air has 21% oxygen. The lungs are comprised of millions of tiny air sacs that inflate when you
20:34breathe in. The air sac is called an alveolus and it's surrounded by a net of alveolar capillaries,
20:41which carry blood from the heart past the air sacs. And they form kind of like a net, a mesh
20:47around
20:48the air sacs. In between the capillaries and the air sac is a super thin membrane, like a microscopic
20:57filter. So when you breathe air in, it's just a matter of diffusion. The 21% oxygen that you breathe
21:07in
21:07is higher than what's in the blood that returns to the lungs from the rest of the body. Because
21:13there's more oxygen in the air sac than in the blood that comes by the air sac, that oxygen diffuses
21:20across that alveolar membrane into the blood. Once the oxygen hits the blood, there's a molecule in the
21:28blood called hemoglobin, which is highly avid for oxygen. So the oxygen molecules attach to that
21:35hemoglobin and it gets carried away back to the rest of the body, which needs the oxygen.
21:40All right. Well, that's all the questions I got today about your lungs. Hope you learned something.
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