00:00:06
I'm engineers in this video we're going
00:00:08
to talk about the mechanics of breathing
00:00:09
so it's going to be a tough topic for
00:00:11
certain people to understand especially
00:00:13
with the pressures so we're going to do
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our best here and engineered science to
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make sense of that so it's going to dig
00:00:18
right in so before we do that we need to
00:00:20
look at a little bit of anatomy for the
00:00:22
lungs and a lot of the chest wall
00:00:23
structure so let's do that first
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so if you look here we have two lungs
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right right left lung and what's going
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to happen is you're going to have you
00:00:31
know the actual trachea the trach is
00:00:32
going to branch off into the right and
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left primary bronchus serving the actual
00:00:36
lung specifically at the smallest
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structural unit called the alveoli we'll
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talk about that in a second but the lung
00:00:44
itself each individual allo lives making
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up the lung but if you look at the lung
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it has this nice little thin epithelial
00:00:52
tissue with a little bit of areolar
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connective tissue clinging on to that
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organ so you just blue layer right there
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that blue layer right there we're going
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to denote this layer right here let's
00:01:02
call this layer 1 ok so layer 1 right
00:01:05
there so layer 1 is specifically called
00:01:08
the actual visceral pleura so again this
00:01:13
layer 1 is actually called the visceral
00:01:18
pleura okay that's the first layer then
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let's keep working our way out now you
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see this space right here this little
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hollow like cavity but it has a little
00:01:30
bit of fluid in it
00:01:31
this space right here we're going to
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call this number 2 here so number 2
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number 2 is actually this whole cavity
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here is actually specifically called the
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pleural cavity now here's what's
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interesting about the pleural cavity in
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this diagram I'm actually showing a
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space in the human body there actually
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is no space it's actually a potential
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space they call it and the reason why is
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in our human body the lungs this
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visceral pleura is tethered or connected
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to the actual this pleura right here
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this last one we'll talk about this last
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one here is called the parietal sclera
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let me write this one down again this
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third one is specifically called the
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parietal pleura but to come back to that
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thought that I was saying remember this
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visceral pleura is almost completely
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tethered to the parietal pleura and how
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they're tethered together and connected
00:02:31
together is through this actual tool or
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cavity what's in the pleural cavity
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pleural fluid there's a little bit of
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like a serious like fluid in here that
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allows for imagine this for a second
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let's say here I take the eraser there's
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a razor is supposed to represent the
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visceral pleura
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here's the marker this is supposed to
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represent the parietal pleura
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technically they are really really close
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together rubbing up against one another
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all the time now you might be saying oh
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wait but if that happens all the time
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wouldn't that produce friction and
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inflammation and tissue damage it would
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I guess what our body does to prevent
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that from happening that pleural cavity
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is occupiable it's called a pleural
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fluid that we said and what that pleural
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fluid does is when the actual layers are
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rubbing up against one another during
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the inhalation exploration processes it
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allows for there to be no friction or
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very little friction and prevents
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inflammation what happens when actually
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in certain situations where there is too
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much fluid accumulation or actually
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there's very little fuel accumulation
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and these layers start rubbing up
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against one another and start causing a
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lot of agitation it can reduce what's
00:03:33
called pleurisy so that is a condition
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that can come about whenever there is a
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lot of friction developing between the
00:03:40
parietal pleura and the visceral pleura
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due to maybe a decreased situation not
00:03:44
enough pleural fluid being produced okay
00:03:46
so again what do we have here we have
00:03:48
the pleural cavity number two and number
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one we have the visceral pleura okay now
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we need to talk about something else we
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need to talk about pressures because
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pressure is an important topic that we
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need to talk about here okay there's
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three main pressures that we're going to
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talk about let's denote these a B and C
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okay so we're going to have called these
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pressures a B and C so this is going to
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be pressure a this is going to be
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pressure B and this is going to be
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pressure C okay press your a pressure B
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pressure C pressure a we're going to
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just name them first
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pressure a is actually referred to as
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the intrapulmonary pressure so it's
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referred to as the intra pulmonary or
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intra alveolar sometimes they'll enter
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alveolar pressure okay and why did I say
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intra alveolar well you really know what
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happens is you know technically whenever
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the trachea is coming here it's getting
00:04:48
away to the bronchi and then it goes
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secondary tertiary and then eventually
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goes to terminal bronchioles respiratory
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and it branches out to these actual
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small structures you see these little
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sacs here you smell a little like grape
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like structures those are called the
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alveoli so technically when I say inter
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pulmonary pressure I really mean enter
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alveolar pressure right which is the
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pressure in here so this is the a
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pressure right the pressure that we were
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talking about but I'm just blowing up
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here for the sake of this video so it's
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very clear right so intrapulmonary
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pressure is this one what is this B
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pressure what is the pressure here in
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this pleural cavity it's called the
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intrapleural pressure not that bad right
00:05:25
that's not bad to remember so again what
00:05:27
is this pressure here it's called the
00:05:28
intra pleural pressure okay sweet deal
00:05:37
and again it's a pressure that actually
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we occupied in this pleural cavity the
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last one which is the C pressure is the
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atmospheric pressure or the barometric
00:05:45
pressure you might even heard that as
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barometric pressure or atmospheric
00:05:52
so-called Bretta barometric pressure
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atmospheric pressure now why am I saying
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all this stuff because this is going to
00:06:01
be critical once we get these actual
00:06:03
pressures down the numbers then it's
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going to make this whole mechanics a lot
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easier okay so now we're going to do is
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we're going to give you numbers for each
00:06:11
one of these pressures I gotta explain a
00:06:12
little relationship between the two okay
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so I'm going to write these down here so
00:06:16
the entry of pulmonary pressure is
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approximately approximately we're going
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to denote it as p-pull okay and people
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is just the noting that's the intra
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pulmonary pressure it is approximately
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760 millimeters of mercury that's the
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unit that they're actually measuring it
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in right
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then this next one intrapleural pressure
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intrapleural pressure is approximately
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and we're going to denote this is P I P
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so we're going to denote this is p IP
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representing that it's intrapleural
00:06:49
pressure intrapleural pressure is
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approximately is always negative we
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refer to it as a negative pressure and
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i'll explain what that means when I mean
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negative pressure hang in there a little
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bit intrapleural pressure is always less
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than the intrapulmonary pressure you
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might be like okay well how much about 4
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millimeters of mercury less than the
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intra pulmonary and Traveller pressure
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so what's 4 - 760 is about 756 so this
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is approximately 756 millimeters of
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mercury which again those are the units
00:07:19
for this pressure and the last one is
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going to be the atmospheric pressure the
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atmospheric pressure the barometric
00:07:25
pressure at sea level at one atmosphere
00:07:27
usually and we say is approximately
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about 760 millimeters of mercury okay so
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let's write this one down we'll put P
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and we'll put ATM which is atmospheric
00:07:37
pressure this is approximately 760
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millimeters of mercury
00:07:42
again millimeters of mercury is the unit
00:07:44
sometimes they use centimeter of water
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at certain situations right okay we're
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going to use millimeters of mercury in
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the situation I'm not going to send me
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to the water okay now now that we have
00:07:56
all the pressures I want to explain a
00:07:58
little bit about these pressures
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primarily one of the ones that bug
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people out a lot is the intrapleural
00:08:02
pressure I want to talk about this a
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little bit before I do that though I
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want to correlate this thing when we
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talk about I'm going to use these terms
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a lot negative and positive and zero
00:08:10
pressures when we compare pressures so
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if it's zero pressure negative pressure
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positive pressure we compare it to the
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atmosphere okay so for example the
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atmospheric pressure is 760 millimeters
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of mercury all right
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what is the intrapulmonary pressure 760
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millimeters of mercury
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what is 760 - 760 it's zero so this is
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called this is actually technically we
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can also write that this pressure here
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this intrapulmonary pressure is also
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zero millimeters of mercury right and
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that's because so sometimes just so you
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know these can be interchangeable I
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could put 760 or I could put zero all
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that means is that it's equal to the
00:08:49
atmospheric pressure okay now let's
00:08:51
compare intrapleural pressure to
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atmospheric pressure
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okay 760 - 756 is four millimeters of
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mercury but it is a lot when we think
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about this one okay what we're actually
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doing is I should actually rephrase this
00:09:07
when you're subtracting you're
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subtracting intrapulmonary - atmospheric
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and you're subtracting intrapleural from
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atmospheric so if I'm actually
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subtracting 760 from 760 at zero but if
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I subtract 756 - 760 what is that that's
00:09:21
negative 4 ok sorry about that max all
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right all right so now this
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intrapulmonary pressure technically we
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could also write it is actually negative
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4 millimeters of mercury okay now that
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we have these numbers out of the way
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right so this is a negative pressure
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this is a zero pressure here I want to
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explain why this is negative because
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this bugs people out okay let me take
00:09:49
intrapleural pressure down here there's
00:09:50
three reasons why intrapleural pressure
00:09:52
is actually negative so let me explain
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this real quick so intra pleural
00:09:58
pressure or as we denote it here we
00:10:02
denote it as as V P IPL refer to this a
00:10:06
lot right so it's a negative pressure
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there's three reasons why this is a
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negative pressure okay first reason is
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the elasticity of the lungs okay so the
00:10:19
first reason is the natural elasticity
00:10:23
of the lungs second reason is what's
00:10:29
called surface tension will have another
00:10:31
video specifically on surface tension
00:10:33
and surfactant but this one is going to
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be surface tension and then the last
00:10:40
thing is going to be the elasticity of
00:10:42
the chest wall so the last thing is
00:10:44
going to be the elasticity of the chest
00:10:48
wall
00:10:50
okay let me explain what I mean by this
00:10:52
and there's also one last thing that
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I'll mention and it's not with respect
00:10:57
to this it's due to the differences in
00:10:59
the intrapleural pressure throughout the
00:11:00
Interpol cavity and this is due to
00:11:02
gravity I'll mention this last one okay
00:11:06
but again this is not really one of the
00:11:09
things that's contributing to it it's
00:11:10
contributing to a difference in the
00:11:12
pressures okay so it can contribute the
00:11:14
differences in the pressure I'll explain
00:11:15
what I mean by that because you can see
00:11:17
that the pressure intrapleural pressure
00:11:18
could be different here here in here
00:11:20
I'll explain that first off elasticity
00:11:23
of the lungs in the surface tension
00:11:24
we're going to group those together for
00:11:26
a second and let me explain why now what
00:11:29
first off what is the definition of the
00:11:30
last things how would you define
00:11:32
elasticity elasticity is whenever you
00:11:35
try to stretch something right it
00:11:36
doesn't want to be stretched it wants to
00:11:38
resist the actual desire to be stretched
00:11:40
it wants to recoil it always wants to
00:11:42
assume the smallest size possible
00:11:43
that's what elasticity is think about
00:11:46
this for a second where is this
00:11:48
elasticity coming into play well
00:11:49
technically
00:11:50
whenever the lungs want to recoil what
00:11:53
are they actually doing imagine again I
00:11:54
told you that imagine the parietal
00:11:57
pleura in the visceral pleura is
00:11:58
actually close together actually
00:11:59
touching when I try for my lungs to
00:12:03
actually deflate if I try to deflate
00:12:05
them what is it going to do to the
00:12:06
visceral part it's going to pull it away
00:12:08
as it pulls it away because it's time
00:12:11
trying to deflate it trying to get
00:12:12
smaller as the lungs is trying to get
00:12:14
smaller it's pulling away from pulling
00:12:17
this visceral pleura away from the
00:12:18
parietal pleura now let's do surface
00:12:21
tension what a surface tension doing
00:12:23
surface tension is this concept that
00:12:25
because of the water molecules this
00:12:27
interaction between the air in the
00:12:29
alveoli and the water molecules it
00:12:31
causes this tension at the air water
00:12:33
interface and the whole thing is is that
00:12:35
the alveoli wants to collapse it wants
00:12:37
to assume the small size possible so
00:12:39
another words same thing what's the
00:12:40
overall purpose the lungs are trying to
00:12:43
pull this visceral pleura away from the
00:12:44
parietal pleura
00:12:45
okay well that's trying to collapse the
00:12:47
lungs and increase this this volume here
00:12:51
okay that's one thing that's happening
00:12:53
the next thing that's happening is the
00:12:55
elasticity of the chest wall okay what's
00:12:58
the chest wall trying to do well you
00:13:00
know normally our chest wall is decently
00:13:01
elastic there's a lot of you know the
00:13:03
costal cartilage
00:13:04
we have a lot different types of
00:13:05
connective tissue that is allowing for
00:13:06
the chest wall to expand so the chest
00:13:09
wall if we were to kind of show this
00:13:10
here let's say that I'm going to
00:13:11
represent the chest wall and this collar
00:13:13
here and I'm going to represent the
00:13:16
elasticity of the lungs and this and the
00:13:19
surface tension the green color what
00:13:21
direction is it trying to pull lungs is
00:13:23
trying to pull it this way that's what
00:13:24
it's trying to do is trying to pull the
00:13:26
lungs in this way to collapse them
00:13:28
whereas the chest wall when you're
00:13:30
breathing what is it trying to do it's
00:13:32
trying to push the chest wall out to
00:13:35
expand the chest wall and if it's trying
00:13:38
to expand the chest wall what is that
00:13:39
doing it's pulling this parietal pleura
00:13:41
away from the visceral pleura if you're
00:13:44
pulling this actual parietal pleura away
00:13:46
from the visceral pleura what is that
00:13:48
doing to this volume in here it's
00:13:49
increasing the volume so the dynamic
00:13:52
interplay between these three concepts
00:13:54
here the elasticity lungs the surface
00:13:56
tension and the elasticity of the chest
00:13:57
wall what is the overall result of all
00:13:59
of these the overall results of all of
00:14:02
these three things is that they're
00:14:05
increasing or they're attempting to
00:14:08
they're not necessarily doing but
00:14:09
they're attempting to they're increasing
00:14:11
thoracic cavity volume which is that
00:14:17
intrapleural space right there that
00:14:19
pleural cavity space right the others of
00:14:22
a law Boyle he came up with a law and
00:14:25
what that law is it states that okay
00:14:29
pressure if you have a certain pressure
00:14:31
here let's say I call it p1 v1 is a
00:14:35
volume p2 is a second pressure and then
00:14:38
a v2 which is the second volume right he
00:14:41
says based upon this relationship okay
00:14:43
based upon this relationship whenever
00:14:46
because it's it's in this format
00:14:48
whenever I increase the pressure of this
00:14:50
reaction whatever reaction it might be
00:14:53
it's going to decrease the volume that's
00:14:55
the relationship with Boyle's law so
00:14:57
Boyle's law states that whenever there
00:15:01
is a increase in the pressure there will
00:15:05
be a direct decrease in the volume same
00:15:07
thing let's say that we actually do
00:15:09
something opposites let's say that I
00:15:11
increase the volume
00:15:12
whenever I increase the volume what is I
00:15:13
going to do the pressure it's going to
00:15:14
drop the pressure
00:15:16
oh that's interesting because isn't the
00:15:20
whole purpose to make this pressure
00:15:22
negative or decrease the pressure below
00:15:24
the intrapulmonary have it always being
00:15:26
a little bit lower or negative pressure
00:15:28
yes and that's the whole purpose that's
00:15:30
why the intrapleural pressure is
00:15:32
negative again one of those three
00:15:33
reasons the elasticity loans where they
00:15:35
want to do cause the lungs to snap and D
00:15:38
and actually collapse that back to their
00:15:39
small size possible surface tension
00:15:41
wants to collapse the alveoli which
00:15:43
tries to collapse the lungs pushing this
00:15:45
way creating a bigger volume of
00:15:46
potential volume space chest wall the
00:15:49
last tasting the chest wall constantly
00:15:51
whenever we're inspiring it wants to try
00:15:53
to bring the actual chest wall out
00:15:54
that's what you want to whenever you
00:15:55
bring area and what do you want to do
00:15:57
you want to try to expand that chest
00:15:58
wall so the chest wall is natural
00:15:59
elastic and it wants to express expand
00:16:01
out this way what is that trying to do
00:16:03
it's trying to pull on the parietal
00:16:07
pleura away from the visceral pleura but
00:16:09
normally in our chest wall when it's not
00:16:12
contracting what would it actually do it
00:16:14
can wreak low also so because of that
00:16:16
sometimes what it can do you know just
00:16:18
say that it's only ever going this way
00:16:20
it prefers to be expanded but it can
00:16:22
have an actual recoil capability here
00:16:25
too okay so it does have a little bit of
00:16:27
recoil capability here too but
00:16:31
nonetheless the dynamic interplay
00:16:33
between the elasticity
00:16:35
surface tension and the elasticity of
00:16:37
the chest will play a role in
00:16:38
maintaining this negative intrapleural
00:16:40
pressure maybe there's actually one more
00:16:41
thing you know there's lymphatic vessels
00:16:44
in this area let's say that I represent
00:16:47
this lymphatic vessels with this Brown
00:16:48
structure here let's say here I put a
00:16:50
little tube in here here's this little
00:16:52
tube and there's brown tube right here
00:16:54
and I'll put another one right here
00:16:55
this brown tube right here are lymphatic
00:16:59
vessels let's say that these are the
00:17:00
lymphatic vessels okay so this is my
00:17:02
lymphatic vessels you know what's really
00:17:06
important about this pleural cavity is
00:17:07
that we want to make sure that there's
00:17:09
not too much fluid accumulating on in
00:17:11
this area we don't want there to be too
00:17:13
much fluid and one of the ways that we
00:17:15
control that okay so here let's see
00:17:17
here's our pleural fluid right here's
00:17:18
our pleural fluid to prevent excessive
00:17:22
amounts of plural flow from accumulating
00:17:23
you know we have we have these little
00:17:25
lymphatic vessels from the bronco
00:17:27
mediastinal trunk area right that can
00:17:29
drain this actual
00:17:30
plural cavity and prevent the excessive
00:17:32
amounts of fluid from building up
00:17:33
because you know what happens if we
00:17:35
build up a lot of fluid it's going to
00:17:37
start trying to push on the lungs right
00:17:39
so we don't want that so again
00:17:41
pleural fluid is constantly being
00:17:43
actually drained out by learn Phatak
00:17:44
vessels to maintain a nice volume in
00:17:46
here so it doesn't disturb the
00:17:47
intrapleural pressure also okay so we
00:17:50
got that down so again what do we
00:17:52
covered so far recovered visceral pleura
00:17:53
is this little epithelial tissue layer
00:17:55
clinging to lung pleural cavity which is
00:17:57
this potential space right consisting of
00:17:59
a pleural fluid and we talked about the
00:18:01
third thing which is the parietal pleura
00:18:03
which is this layer clinging to the
00:18:04
chest wall then we said there's three
00:18:05
pressures in the lung or basically
00:18:07
across this whole lung structure here
00:18:09
right intrapulmonary pressure which is
00:18:11
also called the intra alveolar pressure
00:18:13
right and again we showed it by this
00:18:14
alveoli there it's approximately 760
00:18:17
millimeters of mercury then we said that
00:18:19
there's a pressure here which is the
00:18:20
intrapleural pressure which is 756
00:18:22
millimeters of mercury and then we said
00:18:24
there's an atmospheric pressure outside
00:18:25
of the body right around us that is the
00:18:28
atmospheric pressure which is
00:18:29
approximately 760 but I said we could
00:18:31
express it another way if I take the
00:18:33
intra pulmonary pressure and subtract it
00:18:34
from the atmospheric what is that that
00:18:36
is zero if I take the intrapleural
00:18:39
pressure and subtract from the
00:18:40
atmospheric pressure what is that that's
00:18:42
negative four okay and we explain why is
00:18:44
it a negative pressure because the
00:18:47
elasticity of the lungs in the surface
00:18:48
tension they want the lungs to collapse
00:18:49
they want to assume the small size
00:18:51
possible which is going to increase this
00:18:52
actual volume of this space potentially
00:18:55
then we also said that the elastic is a
00:18:58
chest wall two things can happen
00:18:59
whenever we're inspiring the chest wall
00:19:00
would want to expand outwards but
00:19:02
whenever we're resting it wants to kind
00:19:04
of actually just maintain that size but
00:19:05
it can have a force that's kind of
00:19:07
trying to direct inwards a little bit
00:19:08
right but no matter what the dynamic
00:19:11
interplay between the elasticity the
00:19:13
lungs the surface tension and the
00:19:15
elasticity of the chest wall helps to
00:19:16
keep this volume increasing and by
00:19:19
Boyle's law we said that whenever the
00:19:20
volume is increasing the pressure in
00:19:22
this actual cavity is decreasing okay so
00:19:26
because of this because the thoracic
00:19:27
cavity volume decreases I'm sorry
00:19:30
because the thoracic cavity volume
00:19:31
increased I'm sorry this would actually
00:19:33
decrease the actual thoracic cavity
00:19:35
volume but specifically the intra not
00:19:39
thoracic cavity volume but thoracic
00:19:40
cavity pressure so we've actually
00:19:42
decrease T
00:19:45
plural pressure okay because the Boyle's
00:19:49
law so again whenever you increase the
00:19:51
volume and thrash the cavity it's going
00:19:53
to decrease the thoracic cavity volume
00:19:54
pressure but specifically that pressure
00:19:56
that we call the thoracic cavity
00:19:58
pressure is really the intrapleural
00:20:00
pressure and that will decrease to about
00:20:02
negative four and then again we said
00:20:04
that the pleural fluid is actually
00:20:07
constantly being pumped out of the
00:20:08
pleural cavity by blowing fatik vessels
00:20:10
like the bronco mediastinal trunk to
00:20:12
maintain a normal volume so it doesn't
00:20:14
interfere with the actual intrapleural
00:20:16
pressure one more thing and then were
00:20:18
going to go over these actual changes of
00:20:20
how breathing is affected here gravity I
00:20:23
mentioned gravity
00:20:24
now when gravity is actually acting
00:20:26
downwards what happens let's say that I
00:20:29
actually pretend for a second that I
00:20:32
take the bottom of this long-hair I take
00:20:34
the bottom of this long and I try to
00:20:35
yank it down by gravity as I yank the
00:20:38
bottom of this lung down by gravity it's
00:20:41
going to pull on the apex - so I want to
00:20:43
pull the apex farther away what part of
00:20:46
my pulling farther away I'm pulling the
00:20:47
visceral pleura farther away from the
00:20:50
parietal pleura okay so as I'm yanking
00:20:53
down at the base of this long I'm
00:20:54
pulling down here I'm bringing this
00:20:56
visceral pleura closer to this product
00:20:59
apart but when I'm pulling I'm also
00:21:01
pulling on this apex here because
00:21:03
remember these are kind of closely
00:21:04
attached right they're almost really
00:21:06
like just rubbing up against one another
00:21:07
so I pull down here it starts pulling
00:21:10
this actual visceral pleura way from
00:21:12
that private aura so now if you think
00:21:14
about it for a second what's happening
00:21:17
to this volume here when I stretch and
00:21:18
pull that base down what's happening to
00:21:20
I bully the volume here is decreasing
00:21:22
what does that say for the pressure the
00:21:25
pressure will be a little bit larger in
00:21:26
this area what about up here
00:21:28
well I'm pulling this down if I'm
00:21:31
pulling the visceral pleura away from
00:21:32
the parietal pleura up here what does
00:21:33
that mean that what that means that the
00:21:35
volume up here will be a little bit
00:21:36
greater than it was down here so what
00:21:38
does that mean for the pressure the
00:21:39
pressure will be a little bit lower up
00:21:42
there now we're not going to
00:21:43
specifically talk about that but I want
00:21:45
you guys to realize that there
00:21:46
intrapleural pressure is not uniform
00:21:48
throughout the entire pleural cavity it
00:21:50
is different it's approximately like 758
00:21:52
here 756 here in 753 up here we're only
00:21:56
going to refer to
00:21:57
at 7:56 but I do want you to realize
00:21:59
that it isn't uniform throughout the
00:22:00
entire pleural cavity okay now we got to
00:22:05
do another thing that I need to mention
00:22:07
here that is really really important
00:22:09
we're not going to spend a lot of time
00:22:10
but I want you understand that there is
00:22:11
other pressures a pressure across a wall
00:22:14
so for example remember we said that
00:22:17
this was intrapulmonary pressure let's
00:22:19
denote it again with a B this is a right
00:22:22
here but we're going to just denote this
00:22:23
a here for a second again entry I'll be
00:22:25
able to pressure and travel pressure I'm
00:22:27
just to noting in here so it's close to
00:22:28
this this is the B pressure which was
00:22:31
the intrapleural pressure and here was
00:22:33
the seed pressure let's say I make a
00:22:36
line here I have a pressure that's being
00:22:40
exerted across these two walls okay
00:22:44
so there's a pressure that's being
00:22:45
exerted across these two walls then
00:22:48
there's also another pressure let's do
00:22:50
this one in pink there's a pressure
00:22:52
being exerted across the chest wall
00:22:56
there's a pressure being observed across
00:22:58
the chest wall what are these two
00:23:01
pressures and why are they important
00:23:03
this pressure here across this wall
00:23:05
which is the difference between the
00:23:07
intrapulmonary and the intrapleural
00:23:08
pressure this pressure here that is
00:23:11
across this wall let's write it
00:23:12
according with the color this pressure
00:23:14
is called B let's write it down here
00:23:16
trans pulmonary pressure
00:23:26
that's interesting or you have to note
00:23:28
this TP to make it easier so TP there's
00:23:32
no transpulmonary pressure okay
00:23:33
alright so that's good for right now
00:23:35
we're going to talk about that in just a
00:23:36
second then there's a pressure exerted
00:23:40
across this chest wall and it's the
00:23:43
difference between the intrapleural
00:23:45
pressure in the atmospheric pressure
00:23:47
okay what is that pressure called this
00:23:50
pressure here is called the trans
00:23:52
thoracic pressure it's called the trans
00:23:57
thoracic pressure okay and we'll just
00:24:05
call this one TTP
00:24:07
alright whatever it doesn't matter but
00:24:09
as long as you understand that the TP is
00:24:11
the transpulmonary pressure and the TTP
00:24:13
is the transfer Rasik pressure okay
00:24:15
there is one more unmentionable we're
00:24:17
not going to really spend a lot of time
00:24:18
on because it's not super super
00:24:21
significant here but I will mention it
00:24:23
quickly it's the pressure all the way
00:24:25
from a all the way to C and this
00:24:31
pressure here is actually called the
00:24:33
trans respiratory pressure I'll write it
00:24:34
up here trans respiratory pressure okay
00:24:42
so I just want to explain something real
00:24:43
quick here all right so now with the
00:24:47
trans respiratory pressure and with this
00:24:48
transthoracic pressure and trans
00:24:50
pulmonary pressure what is the
00:24:52
significance of this okay well let's
00:24:54
write out a little formula here so let
00:24:55
me actually bring this one down a little
00:24:57
bit so we have more room I'm going to
00:24:59
bring this one down here so this is
00:25:00
again trans thoracic pressure and again
00:25:06
we denote as that is TTP all right so
00:25:09
TTP here okay now transpulmonary
00:25:14
pressure what do we say we said it was
00:25:16
the difference from the intra pulmonary
00:25:18
a minus B that's the difference so what
00:25:21
do we actually say we're not going to
00:25:22
say a minus B we're going to say it's B
00:25:24
P pull which is the intra pulmonary
00:25:27
pressure minus the B will be was the
00:25:30
intrapleural pressure so we're going to
00:25:32
put intra plural pressure
00:25:34
this is equal to the trans pulmonary
00:25:37
pressure
00:25:38
okay well what is that let's get a
00:25:40
number out of this bad boy
00:25:41
let's say that this is at rest okay with
00:25:45
intrapulmonary pressure we said was
00:25:46
about I'm sorry
00:25:48
760 millimeters of mercury but again we
00:25:50
could use zero also wouldn't matter if
00:25:52
you use your we'll do zero just for the
00:25:53
heck of it zero for that one and then
00:25:56
negative 4 for the intrapleural okay
00:25:58
let's write that down
00:25:59
so the intrapulmonary again I could have
00:26:02
put 760 and I could have put 4/7 756 it
00:26:07
doesn't matter but what we're going to
00:26:08
do is enter pulmonary pressure here is
00:26:10
going to be specifically zero let me do
00:26:13
some mercury and then what is it over
00:26:16
here for this negative so it's minus
00:26:18
intrapleural pressure which is negative
00:26:20
four so then if I do 0 minus minus 4
00:26:25
it's just I'm adding right I'm adding in
00:26:27
this case and I should actually use the
00:26:29
unit's right I shouldn't be lazy let me
00:26:32
put the unit's in here so I'm consistent
00:26:34
I'm sorry negative 4 millimeters of
00:26:37
mercury the difference in this will give
00:26:40
me 4 millimeters of mercury so you see
00:26:43
how if I took 760 minus 756 it would
00:26:46
still give me 4 millimeters of mercury
00:26:47
well let's even define it a little bit
00:26:49
more it's positive it's not negative
00:26:52
it's positive what does that mean for to
00:26:54
be positive if the transpulmonary
00:26:56
pressure is positive that's good thing
00:26:58
that means that the lungs are actually
00:26:59
going to be able to be inflated if it's
00:27:02
negative that's a bad thing that means
00:27:03
it's going to try to deflate okay let's
00:27:05
now let's do the transfer Rasik pressure
00:27:07
the transthoracic pressure we said was
00:27:09
the difference across the chest wall so
00:27:11
it's intrapleural pressure minus the
00:27:14
atmospheric pressure okay let's do that
00:27:15
one so we said T T P which is a
00:27:19
transthoracic pressure is equal to the
00:27:23
anti b intrapleural pressure so I'm
00:27:25
going to put P IP minus B atmospheric
00:27:29
pressure which is the pressure C so P of
00:27:31
the atmosphere what does that give me
00:27:35
okay intrapleural pressure we said was
00:27:38
negative 4 so we're going to write here
00:27:40
it was negative 4 millimeters of mercury
00:27:43
and then the atmospheric pressure is
00:27:46
zero zero millimeters of mercury
00:27:50
okay so then if that's the case then
00:27:54
transthoracic pressure is actually just
00:27:57
equal to the intrapleural pressure then
00:27:59
because this is zero so what does this
00:28:01
actually equal then this equals negative
00:28:02
four minus zero which is negative four
00:28:05
millimeters of mercury and so what does
00:28:08
that mean that negative formula musa
00:28:10
mercury means that is trying to deflate
00:28:12
that's why the chest-wall because of
00:28:15
this if you look at the actual
00:28:16
transthoracic pressure naturally this is
00:28:18
actually going to one to try to come
00:28:20
this way right it's not going to want to
00:28:22
be inflated it will actually cause a
00:28:24
deflating pressure so the transthoracic
00:28:26
pressure is a deflating pressure okay so
00:28:30
we've done transpulmonary transthoracic
00:28:32
there is the last one we can mention it
00:28:34
really quickly and it's just again intra
00:28:37
alveolar pressure right here minus the
00:28:39
atmospheric pressure so if we wrote that
00:28:41
one down just for the heck of it it
00:28:44
would be the intra pulmonary pressure
00:28:47
right so trans respiratory pressure
00:28:48
we'll call this one t RP so trans
00:28:51
respiratory pressure is equal to thee
00:28:53
p-pull minus D P of the atmospheric
00:28:57
pressure okay well what is that equal to
00:28:59
that's equal to zero minus zero so will
00:29:03
this be it'll be zero millimeters of
00:29:05
mercury and again we're doing all of
00:29:06
this at rest this will be zero
00:29:11
millimeters of mercury is all arrest
00:29:14
we're going to compare this to what it
00:29:16
would look like afterwards whenever
00:29:17
we're going to do the inspired
00:29:18
inspiration process all right so again
00:29:21
with all these pressures let's quickly
00:29:22
go through them trans respiratory
00:29:24
pressure is the intra pulmonary pressure
00:29:26
minus the atmospheric pressure so
00:29:27
therefore it is zero millimeters of
00:29:29
mercury so therefore there's no real gas
00:29:31
flow that's moving in any direction here
00:29:33
and there is no pressure differences
00:29:34
across this okay transpulmonary pressure
00:29:37
this is a really important one this one
00:29:39
in transthoracic are the more important
00:29:41
pressures transthoracic pressure
00:29:43
I'm sorry transpulmonary pressure is the
00:29:45
intrapulmonary minus to enter plural and
00:29:47
we said again you'll take this zero
00:29:49
millimeters of mercury which was 760
00:29:51
again we could write like that
00:29:52
my name is the intrapleural which could
00:29:54
either be 756 or is here right negative
00:29:56
four doesn't matter you're still going
00:29:57
to get the same number which is going to
00:29:59
be positive four millimeters of mercury
00:30:00
again what does that mean
00:30:03
that means that this is trying to expand
00:30:06
ours that you want what you won here is
00:30:08
you want this actual long to be able to
00:30:11
inflate right you want it to be able to
00:30:13
inflate so positive pressure means that
00:30:14
you're trying to inflate the structure
00:30:16
now if we look at transthoracic pressure
00:30:19
what's happening here this one's a
00:30:21
little interesting right because you're
00:30:23
taking the intrapleural pressure
00:30:25
subtracting from the atmospheric
00:30:26
pressure but what do you really what are
00:30:28
you actually left with you're really
00:30:30
only left with intrapleural pressure so
00:30:33
if that's the case then you're
00:30:34
transthoracic pressure is equal to your
00:30:36
actual intrapleural pressure negative
00:30:38
four millimeters of mercury so what does
00:30:40
that mean then it goes back to that
00:30:41
thing that we said is due to this
00:30:43
natural outward elasticity or recoil of
00:30:47
the chest wall right because that's
00:30:48
trying to pull this what parietal pleura
00:30:52
away from the visceral pleura which is
00:30:53
increasing this volume what else did we
00:30:54
say we said it was also due to the
00:30:56
natural elasticity and the surface
00:30:58
tension of the lungs which is trying to
00:30:59
pull the actual visceral pleura away
00:31:01
from the product Laurel what is that
00:31:02
doing to the volume it's increasing me
00:31:04
volume and what would that do to the
00:31:06
pressure in this area it'll decrease the
00:31:08
pressure and that's why this should make
00:31:11
sense okay now that we've done that
00:31:15
we've gone over a whole bunch of
00:31:16
pressures and a whole bunch of different
00:31:18
formulas and numbers I'm sorry about
00:31:19
that
00:31:20
what we're going to do is we're going to
00:31:21
go over how is these pressures changing
00:31:25
whenever we're going through the
00:31:26
inspiratory process so if you guys stick
00:31:28
with us go to part two we're going to
00:31:30
specifically see how the nervous system
00:31:32
is affecting the actual this whole
00:31:34
respiratory structure here and how
00:31:36
that's actually producing pressure
00:31:37
differences all right engineers I'll see
00:31:39
you in part two
