What is asthma? | Respiratory system diseases | NCLEX-RN | Khan Academy
28
August

By Adem Lewis / in , , , /


– [Voiceover] When I
first started thinking about this video, I realized
that asthma is going to be hard to talk about because
so many people have it, everybody knows at least
a little bit about it, so it might be hard to get really to the bottom of what really is asthma. So, to do this, let’s go all
the way back from the beginning. Let’s just start by
talking about the lungs, and what they look like and what they do. So, we have here your big trachea, and they branch off into
your left and right bronchi. Those are the two main stems of the lungs. And from there, they keep branching off like branches on a tree, and
they get smaller and smaller. There are countless levels. I’m gonna just try to draw
a few levels here for us. So they keep branching off
like this, you get the idea. When we inspire, or when
we breathe in, inhaling, it’s kind of like a vacuum
cleaner sucking air in. And these are all the tubes
that are connected to it. So this is like the big hose. If you can imagine your vacuum breaks down into little hoses, that’s
basically what it looks like. So in our lungs oxygen goes
in, when we breathe in. O2 is oxygen, two oxygens. And then on the reverse
side when we breathe out, we breathe out carbon dioxide,
which is the symbol as CO2, one carbon and two oxygens. Now asthma is classified
as an obstructive disease where air is blocked on the
way out, breathing out CO2. But we’ll get to that later
exactly where that happens. For now if we are just
looking at the set of tubes, otherwise known as our
airway, and anywhere we go, if we take a cut like this
across any of the tubes and we look at it up
the tube, or we look at what is called a cross section of it, then it’s going to look
something like this. So we have a round shape
for the outside of the tube. And then we have an opening. And in the middle here
we call it the lumen. The lumen is just the inside of any tube. This is where air actually goes through. And here in the walls of the airway, we have connective tissue, we have glands, we have all kinds of things. But I want to talk about
this smooth muscle layer here that’s around in
the wall of the airway. So since it’s a muscle,
then it can have force and change the shape of things around it. So in asthma, what we care about is that the smooth muscles can
actually constrict this airway. So to see what that looks like,
let me draw this again here. Again, if this is the outside of the wall, then a person who has active
asthma happening at the moment, their airway’s going to be smaller, the lumen is going to be smaller, maybe about, let’s say this big. And what has happened, is that
the smooth muscle around it is contracting hard and is
clamping down on that lumen. To make matters even worse, when our body’s inflamed,
it secretes fluid. So into the lumen, which
is usually supposed to be open and dry, we have extra fluid. So when the opening is already smaller, it’s being flooded by mucous and fluid. And this whole picture together is what asthma looks like in our airways. Now I just showed you one tube here, because we cut it once here. But imagine this process is happening in all these vacuum tubes,
all these little levels. So the air is really
having trouble moving. Actually, if you could imagine a vacuum. Let me just draw one here. This is the very primitive
model of our vacuum. And if you could imagine
that this machine has a lot of power sucking air in,
but when it’s coming out, it’s a passive process,
so there’s no power pushing the air out. So even though this constriction here will make it harder to suck air in, but at least it has a motor behind it, as opposed to when the air’s coming out, it just has to passively leave
through the smaller straws. So that makes it harder on the exhale. We’ll come back to what that sounds like when we listen with the stethoscope. But first, let’s talk about
what causes this process. Why would your airway
suddenly clamp down like that? Why would our body allow
it, and what triggers it? So I promise that every
time I talk about lungs, the first thing I will
always say is, smoking. Smoking can be a huge trigger for asthma. Doesn’t even have to be firsthand smoke, it can be secondhand. In fact, kids who have asthma, they’re exposed to parents
who smoke in the house. Even parents who are smoking outside, but then wear the same
clothes inside the house. That can trigger asthma,
because these smoke particles are billions and billions of little things that don’t belong in the lungs, and when they’re in there,
this process can happen. Also because we live in a time where there’s so much machinery around us, this is a car if you can tell… So car exhaust and pollution
in general in the cities can be a huge trigger for asthma. Also people whose jobs expose
them to things like asbestos, or other things they can
inhale can be a trigger. I’m just gonna start writing
cause I can’t draw fast enough. We have paint, remember that
everybody has different triggers. People who have asthma don’t react the same
way to the same things. And this one, I think, is really sad. Some people can be triggered by food. You can be allergic to foods. Or things in beer or wine, can trigger asthma in some people. Now another trigger can
be as common as stress. Our body reacts to stress
in a variety of ways. It can increase inflammation, which asthma is basically
an inflammatory process. So this one I think is interesting. A common drug that most
of us have probably taken, can be be a trigger in up to 30 percent of adults who take this
drug, and that is aspirin. Helps with your headaches, but sometimes causes
your asthma to flare up. And lastly, babies who
are completely different creatures from adults,
they can have GI reflux, or what we call heartburn, where the things in their
stomach go back up the esophagus. Since they are so small, their
system is so close together, it can go up the esophagus
and into the trachea. So they can be triggered by GI reflux. As you can see, this reaches
almost every aspect of life, this is probably why so
many people have asthma, and it’s so different in everyone. So going back to our kind
of clinical, medical way of thinking of asthma, if
you are going to listen to a person breathe
through your stethoscope, and this person has asthma,
what might that sound like? Let me draw a stethoscope. Are we gonna listen to these lungs? Now keep in mind, as I said earlier, there is fluid in here as well, so these smooth muscles constrict, but there’s also fluid and
mucous getting secreted into these tubes as part of our body’s way of dealing with inflammation. So air and fluid together,
what do they form? They form air bubbles. So as these air bubbles pop and reform, and we’re trying to breathe through them, that’s why we would listen. We hear a high-pitched noise
that’s referred to as wheezing. Now wheezing is very characteristic of obstructive diseases, like asthma. Wheezing basically sounds
like a tiny little whistle, so when they inhale and
then exhale, on the exhale you hear high-pitched noise
all over the lung fields. Now I’m going to draw an imaginary line that divides our lung here. So the trachea, this is
called the upper airway, and down here are the smaller airways. A wheezing in asthma is
a small airway disease. It is a small airway disease that happens on the expiration,
or when you breathe out. Now if there’s noise on the inspiration, that’s usually caused by a foreign body, or some other kind of process that makes the upper airway constrict. That doesn’t really
happen with asthma unless it’s super severe, and this
person is just dying for breath. So usually asthma you can get an air in, and it’s on the expiration
that we have a problem and you hear the wheezing. Because again, the
vacuum is sucking in air in the inspiration, so it’s going okay. But when you breathe out, passively, the restriction really causes a problem. So remember: asthma, wheezing,
small airway disease. Now this next part… I don’t have asthma, so I
always feel like I’m not such a good judge on what it really
feels like to have asthma. But we can imagine that
if this person has trouble breathing out, breathing
out is just as important as breathing in, if you can’t do either it’s a very scary process. And this person coming
in will be complaining of shortness of breath,
so shortness-of-breath. SOB is a very commonly used
way to describe the symptom of can’t catch your breath,
panting, shortness of breath. Now depending on how severe
their attack is in the moment, a lot of people have rescue inhalers. When they’re panicking and can’t breathe, this rescue inhaler can
deliver some emergency drugs to open up that airway. And it’s such an important
intervention for people who have asthma to not only breathe, but to feel like they can
breathe, to help with the panic and just the discomfort of not being able to get a breath in and out. Now lastly, I just want to mention that asthma, just from observation, seems to be related to two other diseases. There’s asthma, there’s eczema, which is a disease of the skin. You have excessively dry patches of skin that, again, flares up. It can be red-angry or dry
and peely, a skin disease. And then the third, we have allergies, or some people call it allergic rhinitis, which is more proper for
(mumbling) your nose, rhinitis. But most people are just
calling it allergies. And these three things,
for some reason seem to be good friends, in that
a person who has one, is likely to have the other two. We don’t really don’t know why. We’re still studying why
that relationship exists, but it does, especially in children. So this in a nutshell from
a thousand miles above, is what asthma looks like, what it is. So just a few key words to remember. We have airway constriction,
in the small airway that causes shortness of breath and sounds like wheezing on a stethoscope.


29 thoughts on “What is asthma? | Respiratory system diseases | NCLEX-RN | Khan Academy

  1. i am 13 years old and a couple of months ago we were in PE playing dodgeball and everyone ganged up on me after the game finished and continued throwing them at me so I began getting stressed and eventually started having an asthma attack (I did not have an inhaler).soon after my friend (who was also an asthmatic) realized what was happening and ran to get her inhaler. my other friends ran and told the teacher and I stepped outside. a minute later class ended and people were coming out and started laughing at me having an asthma attack. it just goes to show that people in our generation are dicks

  2. i never panic when i get asthma(attacks) i guess ive just gotten used to it, but how can i keep asthma away or reduce the amount of attacks each month

  3. Well explained video. Im hear to understand my condition more. I experienced an ahstma attack last week and was hospitalized for a week! i was given nebalizers and oxygen tube. I didn't realise how bad my condition was needless to say I get an average of 3-4 chest infection maybe more a year which lead into attacks since then ive been deep into learning more about my condition. I no longer get regular colds they go straight into a chest infection and everything goes downhill from there

  4. I Love all your videos on the respiratory system. I am in school for my NP and I am very visual so this helps further explain everything I have read. Plus your voice is uplifting and doesn't bore me and you keep your videos interesting while informative. The only thing I would state is your forgot about viral/bacterial triggers of asthma (colds). Thank you again for all your visual help!

  5. Wheezing is an adventitious breath sound caused by constriction of the airway, not by gas passing through the fluid and mucus on the membranes. Wheezing is a high pitched whistling sound. The adventitous breath sound caused by air bubbles popping is called rales. It sounds like crisped rice cereal being crushed, can be coarse(larger bubbles) or fine(smaller bubles).

  6. I'm 20 years old and I've suffered with brittle asthma all my life but even after 20 years I know the basic about it now I'm currently in hospital with my 4 attack on the last month watching g a video to see what going on

  7. One time I thought that I had Asthma, but then I didn't. But my friend has Asthma, but only when his mom blows cigarettes smoke in his face. I'm only 4 years old and am watching this video. I wunts tu gos tu Medstickle scul wen I gets oldr!

  8. I NEW IT I HAVE ECZEMA ALLERGIES (minor) AND ASTHMA. And to those asking how it feels, it is like the worst feeling ever, it's not even painful, but it just makes me SWEAT to think about it. 28 million North Americans with the same disease…

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