Doctor Answers Lung Questions

I'm Dr. Ravi Kalhan,

pulmonologist at Northwestern Medicine.

I'm here today to answer your questions from the internet.

This is Lung Support.

[upbeat music]

A Reddit user asks, Why are we able to breathe

both consciously and automatically?

This is super interesting and unique to the lungs,

because no other organ can you consciously control it.

You can't make your kidneys filter more fluid.

You can't really just make your heart start beating faster.

You can't make digestion speed up.

There's no other organ that can do this.

But for the lungs it's essential.

So the brainstem, the oldest part of the brain

in terms of evolutionary terms,

controls breathing automatically

and respiration just happens.

The brainstem makes sure

that the diaphragm keeps contracting,

the lungs keep filling with air and you keep breathing.

That's super important 'cause otherwise,

every time you went to sleep, you'd die, right?

But we also need to talk and laugh

and scream and sing.

So the conscious part of the brain,

the cortex can actually control breathing

in addition to the brainstem.

So in that sense we can both manually control our breathing

as well as have automatic functions that keep us alive.

PurestVideos asks, How exactly do asthma inhalers work?

Well, asthma inhalers contain medicine.

It actually drives me crazy when people only refer to it

as an inhaler 'cause it's a medication,

and they're medicines that we can deliver

straight to the windpipes.

The problem in asthma is the windpipes are over inflamed

because a person is susceptible

to things in the environment like pollen, pollution,

or if someone smokes cigarettes,

that cause inflammation in the windpipes.

So the way we treat that is

with inhaled anti-inflammatory medicine.

Usually that's inhaled steroids.

You can inhale corticosteroids

that treat the surface of the windpipes

so that they get less inflammation

because of those corticosteroids' anti-inflammatory effects.

And then the lungs don't have that inflammation

and people have less asthma symptoms.

Asthma inhalers also often have a bronchodilator.

Those medicines relax the muscle surrounding the windpipe

so that the windpipe can open up

and air can move in and out more efficiently.

IIsSmarter asks, What actually happens

when you get the wind knocked out of you?

Well, when the wind gets knocked out of you,

it usually comes after someone gets hit in the chest

or punched in the gut,

and that's not actually a problem of the lungs.

It's a problem of the diaphragm,

where getting hit right here,

sort of like where the ribs come together,

there's a nerve bundle right there called the solar plexus,

which is not that protected by bones.

It's like right in that open space behind your stomach.

And when you get hit there,

the thought behind the wind getting knocked out of you

is the diaphragm goes into spasm.

So the diaphragm doesn't work right,

you feel like you can't breathe

'cause the diaphragm's not moving down

and then it takes like 30 seconds for everything to reset,

calm down, the diaphragm to relax

and for the person to recover [keyboard clacking]

after getting the wind knocked out of them.

One user asks, Why do humans have two lungs

instead of one single big lung?

It's probably the result of evolution deciding

that having two things, a redundancy,

is better than having one thing.

It's like why does a airplane have

two engines instead of one?

Well that's because if one goes down, the other still works.

Akkitae asks, Does this sound like COPD?

[deep wheezing sound playing]

This doesn't sound like COPD

because COPD usually is characterized

by having less sound in your chest.

COPD stands for chronic obstructive pulmonary disease.

It also gets called emphysema.

So normally the lung is like rubbery

and elastic like a balloon

and if you blow air into it,

[air inflating]

and it's inflated, you take a big breath in

and let it go. [air rasps]

The air just comes out super fast.

When someone has emphysema,

the lung is not rubbery anymore like a balloon.

It's like a plastic grocery bag.

You blow air into it

and the air just kind of sits there and floats

and the air doesn't come out.

And we normally hear less sounds in the lung,

not more sounds in the lung. [keyboard clacking]

With a Bag asks, How TF does a lung transplant work?

Like how do they get the lungs out?

In the old days, we actually used to just take the lungs out

by creating a giant incision in the chest,

opening it up, deflating the lungs

and taking them out.

When they deflate,

they're actually pretty small like the size of your fist.

So these days, there's all kinds of new ways

that they're doing transplants

that make it easier to tolerate the surgery.

So the lung only actually has three connections to the body.

They're connected through a windpipe, through a vein,

which takes blood from the lungs to the heart,

and an artery which brings blood

from the heart to the lungs.

Just those three hookups.

So if you can remove those three hookups

and deflate the lung,

you can actually take it out through a smaller incision.

So that's what's going on now at a lot of places,

that they're doing smaller incisions sort of between ribs

where they can take the lung out

and then put a new lung in.

The way people live during that period

is they're put on a bypass machine

which does the oxygen and gas exchange

for the person while their lungs are going

in and out of the body.

But the manner in which the transplant takes place

at a lot of places is a lot less sort of dramatic,

what we used to call a clam shell,

sort of just cut open and lift up the chest.

Now there are a lot of smaller ways to do it

'cause the lungs can deflate

and reinflate once they're in the body.

Andre the Boss 21 asks,

Did you know that we still don't know why we yawn

and why it's contagious, even across species?

There are some theories about why people yawn.

One of them is debunked,

that the brain or the body needs more oxygen.

That's not why people yawn.

The current most talked about theory

is people yawn because it increases blood flow to the brain

and cools it down.

So it's like a cooling function for the brain.

Why the brain needs cooling,

I don't think we know.

Why yawning is contagious,

some people think is like a old social network thing

of empathy that gets transmitted

sort of naturally in the human state.

Because yawning is considered

sort of this empathetic social response

to people around them,

it takes time to develop that empathy.

And four and five-year-olds in general,

don't have contagious yawning

'cause they haven't developed those empathetic networks,

or so the theory goes. [keyboard clacking]

A Reddit user asks, How does air enter the lungs?

Well this is an interesting question

because while one might think

air gets sucked into the lungs,

it's actually a completely passive process.

There's a muscle below the lungs called the diaphragm,

which is dome shaped.

When you breathe, in that dome flattens

and the lungs have negative pressure in them

compared to what's in the atmosphere.

Air always flows from higher pressure areas

to lower pressure areas.

So when the dome flattens

and there's negative pressure inside the chest,

air enters the chest.

How does air leave the chest then?

Well, the lungs always wanna deflate.

They're filled with air and they're like a rubbery balloon.

So after that negative pressure fills the lungs,

the diaphragm relaxes

and air's natural tendency is to come out

because the lungs are elastic and rubbery.

TrollGirl666 asks, WTF are hiccups

for like why am I being punished for breathing?

Well a hiccup is a pretty weird thing.

It is when the diaphragm tries to breathe,

but then the vocal cords prevent the breath from happening

and there's like this awkward feeling

of where air's trying to go in.

But then it gets cut off up here by the vocal cords,

and no one knows why they happen.

They could be because something irritates the diaphragm.

They could be because something irritates the vocal cords.

Like sometimes people say they drank too much carbonation

and they start hiccuping.

There's no real knowledge for why that reflex exists.

It's probably related to some ancient reflex

that developed over time during evolution,

but they certainly are uncomfortable.

Birken8000 asks,

What chemicals actually make vaping dangerous?

And there are a lot of chemicals in vape juice

that we don't know all the time how dangerous they are.

But it stands to reason that they probably are.

The first big one is if someone's vaping nicotine,

there's nicotine in the vape juice,

at high levels, actually,

it gets heated up in the juice and aerosolized

and then you can breathe it in.

And that's a high concentration of nicotine,

which creates addiction.

Nicotine is a highly addictive chemical.

How dangerous that nicotine is on a day over day basis

is not totally clear,

but being addicted to it creates problems

and desire for more and more nicotine.

There are other chemicals in vape juice that get heated up.

For example, there's formaldehyde.

The stuff used to preserve bodies is in vape juice,

and heating that up and inhaling it,

well, that probably isn't that good

for you in the long run.

There are other things like there's flavors

and these are food safe flavors in vape juice.

So tutti fruitti flavor vape or peppermint

or whatever the vape is, they're probably okay to eat,

but we don't know what happens when you heat them up,

turn them into a volatile substance

and inhale it in the lungs.

That could be really dangerous.

So all these things you know, are, in my mind,

as a pulmonologist, bad for you.

I think, as a lung doctor,

the thing you're supposed to inhale is air.

Gandhi's Account asks, Why does exhaling

after you've held your breath for a long time

feel like you're not suffocating?

Well, when you hold your breath,

you take a big breath in [inhales]

and hold your breath.

You're not breathing.

And when you're not breathing,

the body does not release carbon dioxide.

It also doesn't inhale oxygen.

But in the sense of suffocating,

the carbon dioxide is what matters.

So when you don't exhale carbon dioxide,

it builds up in your blood.

Carbon dioxide is an acid,

so the pH in your blood goes down.

There are receptors in your bloodstream

that feed into the brainstem

and create a sense of needing to breathe

when the pH in the blood goes down

because of this increase in carbon dioxide.

So that's when the brainstem kicks in

and says, Dude, we'd better breathe right now.

So the sense of relief that comes

when you finally start breathing

and feel like you're not suffocating anymore

is because you finally are releasing that carbon dioxide,

the pH in the blood is going back to normal

and the satisfaction of being able

to breathe again kicks in. [keyboard clacking]

RataOBC asks, What's the difference between breathing in

through your nose and mouth

and why it's recommended to do it through your nose?

When you breathe through your nose,

a lot of good things happen.

The nose filters air, there's hair in your nose,

it's the first line of filtering.

And then there's other filtering steps

through what are called ciliated epithelial.

There are cells in the entire respiratory tract

that have little flapper things on it that can move debris

and other mucus out of the way

so that air can go through more smoothly.

When you breathe through the nose,

the air also gets warmed up and humidified.

So that's good.

And then the third thing,

which people don't actually know that commonly

is the sinuses produce something called nitric oxide.

Nitric oxide is what's called a vasodilator.

And when nitric oxide comes into contact with the lungs,

it helps ensure that where air goes,

'cause there's nitric oxide there, the blood also goes

because it opens up blood vessels.

So then we have a really good matching between

where the oxygen goes and where the blood goes.

So oxygen can more efficiently enter the bloodstream.

So those are all benefits of breathing through the nose.

If you breathe through the mouth, those things don't happen.

There's no humidifying, there's no clearance,

there's no nitric oxide.

But what there is is less resistance to airflow.

So when you're exercising and you need to get air in

and out really efficiently,

you shouldn't breathe through your nose.

You should do the natural thing

which is breathe through your mouth.

But when you're just at rest

or not doing anything that involves exertion

there are clear advantages

for why breathing through your nose is better.

EttenCO asks, Why, after running for a while,

do my lungs get that painful burning sensation?

It's actually not your lungs.

The lungs don't have pain receptors,

the windpipes do however.

And when you exercise, you inhale mostly through your mouth.

So all the good stuff that happens

when you breathe through your nose:

humidification of the air, warming of the air,

cleaning of the air, doesn't happen

and everything goes sort of straight in through the mouth.

So if it's cold outside, this symptom might get worse

because it irritates the windpipes

when you breathe in cold air through your mouth.

Google-Bruh asks, Coughing up mucus with blood;

should I be worried?

I think you should be worried.

Anyone who coughs up blood should see a doctor ASAP.

RachelBunny asks, Why does breathing into a paper bag

help with hyperventilating?

One could wonder why someone

hyperventilates in the first place.

Well, it could be caused by lots of things.

The biggest thing is anxiety or distress or panic.

Those are the things that we treat with a paper bag.

When someone hyperventilates, they have lowered the amount

of carbon dioxide in their blood.

It actually turns out that those people

who are hyperventilating have normal oxygen levels.

It's all an ability to lower their carbon dioxide

when they start breathing really fast.

So that makes you feel kind of funny and unsettled,

having a high pH creates a sense of further anxiety,

maybe tingling in the fingertips,

all sorts of weird things

that go on when someone hyperventilates.

If you start breathing into a bag, however,

when you hyperventilate,

the carbon dioxide you breathe out gets stored in the bag

'cause you're sort of pinching it

and breathing in the bag like this.

So you start rebreathing carbon dioxide,

which naturally makes the carbon dioxide level

in the blood go up again.

So the pH goes down, the blood becomes more acidic

or gets closer to normal

and it relieves the sense

that you get when you're hyperventilating

that everything is going wrong.

A Reddit user asks, What happens to food

that accidentally gets in the lungs?

The first thing that probably happens is

you start coughing a ton

because the body has a defense mechanism.

If something that's not supposed to hit the vocal cords

or the main windpipe up here, the trachea,

if something hits that,

there are very, very sensitive cough receptors there

that make someone start coughing like crazy

and the food never makes it down further.

If the food does make it down further,

like a tiny amount of food gets down further,

the body has defense mechanisms for that.

One of the biggest defense mechanisms is

that there are cells in the lungs

that are called macrophages that will surround that thing

and start to sort of degrade it

or take it up so that it can't cause problems.

Don't Spill Me asks, What is going on

when a lung collapses?

Normally the lung stays inflated

only because of a suction effect

of the lung against the chest wall.

There's just like a thin layer of fluid between the lung

and the chest wall

and the lung is kind of just suspended there.

You know if you have a glass and it's condensing

'cause you have ice cubes in it

and it's on a counter, the glass kind of sticks

to the counter because of that fluid

between the glass and the counter.

That's what's going on with the lung.

It stays inflated because of that fluid.

So if something disrupts that layer

or if the lung gets punctured for some reason,

so there's now air between the lung

and the chest wall instead of fluid,

the lung will actually collapse

because it can't stay inflated.

The lung is rubbery and elastic.

It's only staying there 'cause of that suction effect.

So when the lung collapses, the way to treat it is

to insert something called a chest tube

where we stick a tube from the outside,

through between the ribs, into that space between the lung

and the chest wall and suck out the air that got in there

or whatever else is in there.

Sometimes an infection can occur in there,

sometimes blood can end up in there.

Suck that out so then the body can heal,

restore that little fluid layer

and then the lung can stay inflated again.

A Reddit user asks, How do the lungs heal

after a smoker quits?

This is a great question

'cause I think every smoker should quit.

And it's true that a lot of the lung can heal.

Most of that healing happens in the wind pipes,

which are irritated by smoking cigarettes.

So normally the lungs have a defense mechanism

called the mucociliary escalator, which is the flapping

of these things called cilia at the tops of the cells

that line the windpipes.

So when you breathe something in that's toxic,

the cilia kind of can flap it back up.

So if you inhale small particles from cigarette smoke,

the cilia can help clear things out.

Or if the lungs produce too much mucus

'cause they're irritated, the cilia can kind

of flop it back up to your mouth and you swallow it

and it goes to your stomach where it doesn't cause any harm.

One of the biggest bad effects of cigarette smoking is

that it impairs the function of this mucociliary escalator

and actually causes the cilia to disappear.

So there's no defense when someone smokes cigarettes.

When they quit smoking,

that function starts to return over a month or so.

So a lot of people when they quit smoking say, Oh my gosh,

I quit smoking and I'm coughing up all this mucus now.

Well that's because the defense mechanisms

that help you clear out mucus are actually working again.

That's a positive sign.

BRoosterMaster asks,

Every time I cough, a little chunk of my lung comes up.

Is this normal? Do lungs grow back?

Well it's pretty unlikely that that's actually a chunk

of your lung coming up.

It's pretty hard to cough up a chunk of lung.

I don't think that actually happens.

It's probably mucus that's coming up that looks pink,

maybe 'cause there's a little bit of blood in it,

but it's not actually your lung.

Fever Coach Admin asks, Asthma versus pneumonia.

How do lung sounds differ?

Here's the sound of pneumonia.

[burbling sound playing]

So in that clip, someone is talking

or whispering while they have pneumonia.

And when someone has consolidated pneumonia,

pneumonia is when part of the lung fills up

with infection or something else.

So like on this x-ray you can see the normal lung is dark

and black and filled with air.

And then there's this top part here, which is white,

which means it's filled with something.

When the lung consolidates,

it can suddenly transmit sounds

much better than if it's filled with air.

So if the lung is filled with air and you whisper

and I listen with the stethoscope right on that spot,

I won't hear you whispering.

But if it gets consolidated

or filled with fluid, suddenly it can conduct

what is being said at the vocal cords.

So if someone whispers then,

you can actually hear the whispering as sort

of a vibrating sound when you listen over

that part of the lung.

Now we can listen to what asthma sounds like.

[whining, wheezy sound plays]

Asthma in contrast is a problem of the windpipes,

the pipes that lead to those air sacs.

And in asthma, those windpipes become narrowed

so they don't transmit air as well.

So when someone has asthma, we hear air going in

and out of the lungs in a much more prominent way

than we do if someone doesn't have asthma.

So we hear squeaking or wheezing

or various things like that that make noise of air going out

of the lungs that we normally would not hear

as a squeaking, high-pitched noise.

I Promise To Shut Up asks,

How does oxygen go from lungs into blood?

Could you explain in details and simply?

Well, when you breathe in, oxygen enters the lungs

and the air has 21% oxygen.

The lungs are comprised of millions of tiny air sacs

that inflate when you breathe in.

The air sac is called an alveolus

and it's surrounded by a net of alveolar capillaries,

which carry blood from the heart past the air sacs.

And they form kind of like a net, a mesh

around the air sacs.

In between the capillaries and the air sac

is a super thin membrane,

like a microscopic filter.

So when you breathe air in, it's just a matter of diffusion.

The 21% oxygen that you breathe in

is higher than what's in the blood

that returns to the lungs from the rest of the body.

Because there's more oxygen in the air sac

than in the blood that comes by the air sac,

that oxygen diffuses across

that alveolar membrane into the blood.

Once the oxygen hits the blood,

there's a molecule in the blood called hemoglobin,

which is highly avid for oxygen.

So the oxygen molecules attach to that hemoglobin

and it gets carried away back to the rest of the body

which needs the oxygen. [keyboard clacking]

Alright, well that's all the questions

I got today about your lungs.

Hope you learned something.

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