What is Asthma? – Pathophysiology of Asthma

By Adem Lewis / in , , , , /

>>Alex: Hi. My name is Alex Thomas. I am an allergy doctor, but I’m also someone
with asthma. And today, I want to talk about asthma and how
it affects our lungs. I also want to talk about how medications
work to make use feel better. So, let’s take a look inside my lungs. One way to think about the lungs is as a network
of branches that start with one main branch that splits into two branches and continues
on with more and more branches that eventually get so small they can only be seen under a
microscope. Now let’s take a look one branch of the
smallest size. We’re going to zoom in and see what this
airway would look like up close. First off, there are muscle bands on the outside
of the airway. And they are nice and relaxed when your asthma is under control and nothing
active is going on in terms of the disease process. The other important part of your airway is
the inside. In a normal airway, when your asthma is under
control, the inside of the airway is wide open. When the airway is open like this, the air
can move through the airway and in and out of your lungs very easily. In asthma, there are three things that are
going on inside the small airways that make it difficult to breathe. First, the muscle bands tighten around the
airway. These muscle bands are squeezing together
in response to a trigger, such as an allergen, an irritant, exercise or cold air. There are lots of different things that can
make the muscle bands tighten up. And when that happens the airway gets narrower because
of the tightness. And it really squeezes things closed. The second thing that goes on with asthma
is that you have inflammation within the airway. So rather than that nice open space for air
to move through, you have swelling within the airway that narrows the inside. The third thing is that mucus inside the airway
starts to plug things up. And now with this opening much smaller than
normal there is less room for the air to go in and out. And it is much more difficult
for you to breathe. This is what as asthma attack looks like. Now, to help treat an asthma attack what we
need first is a rescue inhaler. A rescue inhaler works in minutes and only lasts a few hours. And what the medication in the rescue inhaler
does, and the only thing it does, is work on these muscle bands. And the way it works
is by loosening these muscle bands. So let’s see what that would look like. So now the muscle bands are loosening. And
the airway is once again more open. But there’s still swelling, because the
inflammation doesn’t go away with the rescue inhaler. So to really open up this airway, to reduce
the inflammation, you need a controller inhaler. A Controller works over days, but lasts much
longer. And that’s important. What the medication in a controller does is
decrease inflammation in the airway. And it works in this area of the airway. Over days of using the Controller on a daily
basis, the inflammation will decrease, the swelling will go down, and the airway will
begin to open over time. And finally, with asthma back under control,
the airway is able to have air come in and out much easier. So now you have an airway
that is open and similar to a normal airway.

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