Respiratory | Mechanics of Breathing: Inspiration | Part 2
Summary
TLDRThis educational video script delves into the mechanics of breathing, focusing on the inspiratory process. It outlines the role of the central nervous system, the diaphragm, and external intercostal muscles in expanding the thoracic cavity. The script explains how these actions decrease intrapleural and intrapulmonary pressures, creating a pressure gradient that facilitates air flow into the lungs. The video uses analogies and models to illustrate these concepts, aiming to provide a clear understanding of the respiratory process.
Takeaways
- 🧠 The process of breathing is controlled by the central nervous system, including the midbrain, pons, medulla, and spinal cord.
- 💪 Key muscles involved in the inspiratory process are the external intercostals and the diaphragm, which are innervated by the phrenic nerve and intercostal nerves, respectively.
- 📉 During inhalation, the contraction of the external intercostals and diaphragm increases the thoracic cavity volume, leading to a decrease in intrapleural and intrapulmonary pressures.
- 🔁 The ventral respiratory group in the medulla also plays a role in stimulating the nerves that control the external intercostals and diaphragm.
- 📌 The external intercostals pull the ribs outward and upward like a bucket handle, while the diaphragm contracts and moves downward, collectively increasing the thoracic cavity volume.
- 🌀 According to Boyle's Law, as the volume of the thoracic cavity increases, the intrapleural pressure decreases, creating a pressure gradient that allows air to flow into the lungs.
- 🌐 The atmospheric pressure remains constant during the breathing process, unaffected by the changes in thoracic cavity volume.
- 🔄 The transpulmonary pressure, which is the difference between intrapulmonary and intrapleural pressures, increases slightly during inhalation.
- 🛑 At the peak of inspiration, the intrapulmonary pressure equals the atmospheric pressure, stopping the flow of air into the lungs until the pressure gradient changes during exhalation.
- 🔮 The entire process of inhalation is a coordinated effort of the nervous system and respiratory muscles to create pressure gradients that facilitate the flow of air into the lungs.
Q & A
What is the role of the external intercostal muscles in the breathing process?
-The external intercostal muscles play a crucial role in the inspiratory process by contracting and pulling the ribs outward, which increases the thoracic cavity volume. This action is often referred to as the 'bucket handle' movement.
What is the primary muscle responsible for the inspiratory process?
-The diaphragm is the primary muscle responsible for the inspiratory process. When it contracts, it moves downward, increasing the volume of the thoracic cavity and facilitating the inhalation of air.
How does the contraction of the diaphragm affect the thoracic cavity volume?
-When the diaphragm contracts, it domes downward, which increases the volume of the thoracic cavity. This movement is essential for drawing air into the lungs during inhalation.
What is the function of the phrenic nerve in the breathing process?
-The phrenic nerve originates from the C3, C4, and C5 nerve roots and innervates the diaphragm. Its stimulation causes the diaphragm to contract, contributing to the increase in thoracic cavity volume during inhalation.
What is the significance of the intercostal nerves in the breathing process?
-The intercostal nerves, which run from T1 to T11, innervate the external intercostal muscles. Their stimulation leads to the contraction of these muscles, further increasing the thoracic cavity volume and aiding in inhalation.
How does the ventral respiratory group in the medulla contribute to the breathing process?
-The ventral respiratory group in the medulla contains nuclei that send axons to stimulate the neurons controlling the external intercostal muscles and the diaphragm, thereby contributing to the automatic regulation of breathing.
What is the relationship between the thoracic cavity volume and the intrapleural pressure during inhalation?
-During inhalation, as the thoracic cavity volume increases due to the contraction of the external intercostal muscles and the diaphragm, the intrapleural pressure decreases according to Boyle's law.
What is the initial intrapleural pressure at rest, and how does it change during inhalation?
-The initial intrapleural pressure at rest is approximately 4 mm Hg. During inhalation, it decreases to about -6 mm Hg due to the expansion of the thoracic cavity.
What is the initial intrapulmonary pressure at rest, and how does it change during inhalation?
-The initial intrapulmonary pressure at rest is approximately 0 mm Hg. During inhalation, it decreases to about -1 mm Hg as the volume inside the lungs increases.
How does the transpulmonary pressure change during inhalation?
-The transpulmonary pressure, which is the difference between the intrapulmonary and intrapleural pressures, increases slightly during inhalation due to the decrease in intrapulmonary pressure relative to the intrapleural pressure.
What is the trans respiratory pressure, and how does it indicate the direction of air flow during inhalation?
-The trans respiratory pressure is the difference between the intrapulmonary pressure and the atmospheric pressure. During inhalation, it is negative (-1 mm Hg), indicating that air flows from the atmosphere into the alveoli.
Outlines
🧠 Central Nervous System and Breathing Mechanisms
The paragraph introduces the second part of a video series on the mechanics of breathing, focusing on how the inspiratory process affects pressure changes. It begins with an overview of the central nervous system, highlighting the midbrain, pons, medulla, and spinal cord. The discussion then shifts to the muscles involved in breathing, particularly the external intercostals and the diaphragm. These muscles are controlled by signals from the cerebral cortex through the spinal cord, specifically the phrenic nerve from C3, C4, C5, and intercostal nerves from T1 to T11. The video aims to explain how these nerves and muscles work together to initiate the process of inhalation.
💪 The Role of Intercostal Muscles in Breathing
This section delves into the function of the intercostal nerves and how they interact with the external intercostal muscles during inhalation. When these nerves stimulate the muscles, they cause the ribs to move outward, creating a bucket handle effect, and the sternum to push outward and upward, increasing the thoracic cavity volume. The video uses an anatomical model to visually demonstrate these actions and explains how these movements lead to an increase in the volume of the thoracic cavity, which is crucial for the breathing process.
📉 Pressure Changes During Inspiration
The paragraph explains the impact of the increased thoracic cavity volume on pressures within the respiratory system. As the volume increases due to the contraction of the external intercostals and the diaphragm, the intrapleural pressure decreases according to Boyle's law. The video details how the pressure changes from approximately 4 mm Hg at rest to about -6 mm Hg during inspiration. It also discusses the corresponding decrease in intra-pulmonary pressure from 0 mm Hg at rest to approximately -1 or -2 mm Hg, indicating that air will flow into the lungs due to these pressure gradients.
🔄 Transpulmonary and Transthoracic Pressures in Breathing
This section further explores the effects of increased thoracic cavity volume on transpulmonary and transthoracic pressures. The transpulmonary pressure, which is the difference between intra-alveolar and intrapleural pressures, becomes more positive during inhalation. Meanwhile, the transthoracic pressure, which is the difference between intrapleural and atmospheric pressures, becomes more negative, indicating that the chest wall is expanding outward. The video concludes by emphasizing that these pressure changes are essential for drawing air into the lungs during inspiration.
🔁 From Inspiration toExpiration: Pressure Equilibrium
The final paragraph summarizes the pressure changes that occur during the inspiratory process and sets the stage for the next video, which will cover expiration. It reiterates that the pressure gradients cause air to flow from the atmosphere into the alveoli until the intra-alveolar pressure equals the atmospheric pressure. The video stresses the importance of understanding these mechanics for a complete grasp of the breathing process and hints at the reversal of these events during exhalation.
Mindmap
Keywords
💡Inspiratory Process
💡Central Nervous System
💡External Intercostals
💡Diaphragm
💡Cervical Plexus (C3, C4, C5)
💡Intercostal Nerves
💡Ventral Respiratory Group
💡Thoracic Cavity Volume
💡Intrapleural Pressure
💡Transpulmonary Pressure
Highlights
Explanation of the inspiratory process and its effect on pressures within the respiratory system.
Role of the central nervous system, particularly the midbrain, pons, medulla, and spinal cord, in initiating the breathing process.
Importance of the external intercostal muscles in the inspiratory process.
The diaphragm's crucial role as a muscle in the breathing process, separating the thoracic cavity from the abdominal cavity.
Voluntary control over skeletal muscles like the diaphragm and external intercostals via signals from the cerebral cortex.
Description of the phrenic nerve, which arises from C3, C4, and C5 nerve roots and innervates the diaphragm.
Functioning of the intercostal nerves from T1 to T11, which stimulate the external intercostal muscles.
The ventral respiratory group in the medulla and its connection to the nerves supplying the external intercostals and diaphragm.
Mechanism by which the external intercostal muscles contract to increase the thoracic cavity volume.
Visual demonstration of the bucket handle movement of the ribs and the pump handle action of the sternum during inspiration.
The diaphragm's action of doming down and its contribution to increasing the thoracic cavity volume.
Decrease in intrapleural pressure during inspiration due to the expansion of the thoracic cavity.
Correlation between increased thoracic cavity volume and decreased intra-alveolar pressure.
Explanation of how the atmospheric pressure remains constant during the breathing process.
Changes in transpulmonary, transthoracic, and transrespiratory pressures during inspiration.
Final equilibrium of intrapulmonary pressure with atmospheric pressure at the peak of inspiration.
Anticipation of the next video, which will cover the mechanics of expiration.
Transcripts
all right ners so if you guys here for
Part Two for the mechanics of breathing
appreciate it what we're going to do now
is we're going to go over exactly how
this actual inspiratory process can
produce these changes in these pressures
okay so let's go ahead and get started
so where does this all start okay let's
say that we have here our actual central
nervous system all right so we have
again the midbrain the ponds the medulla
right so we we'll quickly outline that
again we're going to have the midbrain
here all right
midbrain you'll have the
pawns you'll have the medulla right here
and then you'll even have right here
which is our spinal
cord so we're taking a um an actual
sagittal section here so I'm taking A
sagittal section we're looking at like
that so in other words I'm taking here
and I'm cutting right down all right now
whenever we want to breathe since this
muscle here you see how we have the ribs
we took a cross-section of the ribs here
connecting between the ribs you see
these muscles right here these red
muscles right there these ones right
here are specifically
called the
external intercostals so they're called
the external
intercostals now the external
intercostals are kind of really
important muscles for this entire
inspiratory process okay they're one of
the big ones but an even really really
more important one is this big beast
right here you see this big guy right
here all the way from one end to the
other this big muscle right here is a
very important muscle this big old Beast
right here is called the diaphragm okay
so this is called the
diaphragm so you have two really
important muscles here external
intercrosses which are in between the
ribs and the diaphragm right which is
going to be right here right underneath
it's actually what separates the nice
thoracic cavity from the abdominal
cavity okay now
whenever we want to be able to contract
these since these are skeletal muscles
we have voluntary control over our
skeletal muscles so let's say from the
cerebral cortex right from the cerebral
cortex we'll have it coming down from
here you can't see it but it's coming
down from here right you could have
signals coming down here you could have
signals coming down here and actually
stimulating some specific uh nerves
within the spinal cord right so let's
say for example if this is uh going to
be
C3 C4 and C5 this would come out
activate these sematic motor neurons and
come and
inate the diaphragm okay so this would
be C3 C4 C5 nerve rout this is going to
be specifically called the frenic nerve
they actually call this the frenic
nerve
okay whereas you have another structure
let me get Skelly out of the way here
you have another structure here let's do
this one one
in let's actually do this one in this
nice color here let's say that we keep
coming down here though and we come down
to
about you know we're not going to draw
all of them but there's a couple other
ones down in the thoracic region we'll
just do a couple of them and we'll say
for right here we have from T1 all the
way down to about t11 so all the way
down we're not drawing all of them but
for the sake of it I drew a couple here
from T1 all the way down to about t11
you have these intercostal nerves here
and These Guys these intercostal nerves
are actually going to come and innervate
we actually have them coming through
here they're going to be inating the
external
intercostals and when they inate the
external intercostals they're going to
provide a stimulus to the external
intercostals so so far what do we have
here I'll put it like here so it looks
good let's do this like that yeah all
right so we got the frenic nerve coming
here from the C3 C4 C5 nerve rootes
interva in the diaphragm then we have
from T1 all the way down to t11 we're
going to have this intercostal nerves
right so you're going to have your
inter
costal nerves and this could be
activated by cortical control right so
we have cortical control there but you
know what else can actually stimulate
these also we're going to talk about it
in more detail but you have a specific
set of nuclei located here within the
medulla a spe a special set of nuclei
these nuclei are actually called the
ventral respiratory group and the
ventral respiratory group actually has
connections okay that can actually run
here and
provide these axons that can stimulate
these actual neurons that are going out
to supply the external intercostals as
well as the diaphragm so you have input
coming from the cerebral cortex as well
as even from What's called the vental
respiratory group within the medulla
anyway when these guys are coming out
from the frenic nerve and the internal
inter internal intercostal nerves what's
happening let's first look at how the
actual intercostal nerves are working so
we're work from top to bottom so the
intercostal nerves come over here to the
external intercostal and they cause them
to contract now when the actual external
intercostal muscles contract something
really really cool happens I'm going to
show you personally but then I'm going
to bring in an actual Anatomy model so
we can see it in a better way so what
the external intercostals do is when
they contract they pull the ribs outward
so they pull the ribs like they're
coming out so you know whenever you have
like a a bucket with the two handles so
if you have like a bucket with the two
handles and you pull the handles
actually like this that's exactly what's
happening to the ribs so one thing
that's happening is you're taking the
ribs and pulling them outward which is
increasing the thoracic cavity volume so
as you pull the ribs outward that
increases the thoracic cavity volume
another thing whenever the actual
external neosales contract they pull the
sternum they push the sternum out like
this okay so when they push the sternum
out out and upward like this that
increases the thoracic cavity volume
anteriorly a little bit anterior
posterior whereas whenever the uh ribs
go outward that increases it in a
horizontal volume right either way
nonetheless when the extr cost is
contract they pull up they call it like
a bucket handle movement and then
whenever the actual external Coss is
contract they pull the sternum outward
which is kind of like if you guys ever
seen like the water F like the the old
school ones that you do like the pump
action there that's what they call they
call it like the little water pump
action which is actually pull the
sternum out either way the whole result
is increasing the thoracic cavity volume
okay so I want to give you guys a better
example now so what I'm going to do is
I'm going to bring in the an actual
skeleton model here so we can get a
better idea of what this looks like here
because I want to I want to make sure
that this is really really
understandable here so again here we're
going to have all of these structures
these are our ribs okay so all of these
are the ribs okay the external Cal is
actually attach between the ribs so
let's pretend this is actually a rib
here a rib here the external inter Cal
would attach here now what they do is
the lower part of the rib where the
external intercostal is attaches to it
pulls that rib up so when it pulls the
ribs up what look what it actually would
do it would pull the ribs out like this
so you're actually going to pull them
outward like this okay so whenever
they're Contracting when the external
inter cost is contract they pull the
ribs outward like this now and also what
they do is whenever they're Contracting
they kind of push the sternum outward so
two things are happening the ribs are
going outward and the volume in here is
actually increasing also the sternum is
is coming out farther and the volume in
here is increasing so that should make
sense now okay now let me grab another
model real quickly so we can even see a
little bit better about these actual
muscles here so let me bring this back
in here so if we see here we got the
Skelly now what I'm going to do is I'm
going to take this actual chest plate
here put in front of it okay so if you
guys look here for a second you're going
to notice again here's our ribs but you
see these muscles right here on the edge
these muscles right there are your
external intercostals when they contract
so let's imagine we look at this
external intercostal this point here is
actually going to pull that actual rib
up so this is the insertion this point
here is actually fixed that's the origin
so when it contracts it pulls the
insertion up towards the origin when it
does that again sternum goes out which
increases the thoracic cavity volume and
the ribs come out like a bucket handle
which is increasing thoracic cavity
volume okay so now I'll put these guys
back and we'll get back to our actual
tutorial
here okay so now that we've done that we
should have a good idea what's happening
now so let's actually show that now in a
better way here in this diagram now okay
so that's the first thing that happened
so the thoracic cavity volume is going
to increase so let's say that that
happened the thoracic cavity volume over
here let's say that it actually
increased so it went out wider okay so
if that's the case we would expect the
volume in the thoracic cavity to start
increasing before we do this actually
before I do this let me do one more
muscle so we can get one more muscle in
here last one is the diaphragm okay what
does the diaphragm do we really need to
think about him too right before we go
over there and show that so the
diaphragm when he
contracts what actually happens is he
actually domes down so he actually
depresses if he depresses think about
this for a second let me actually show
you what would look like over here if
this muscle contracts let's say that
it's actual muscle
contracted look at what happened to all
of this volume here look at this let's
say that it actually went down a little
bit oh wow that's a lot of volume there
so if that sucker went down what's going
to happen to this area now what happens
to this volume so now the volume is
increasing by three ways one is the diap
frame is actually depressing increasing
thoracic cavity volume the second one is
the external NE costal are pulling the
ribs upward right and outward which is
pulling them like a bucket handle and
pulling the sternum outward all of those
things are doing what what's the overall
result increasing thoracic cavity volume
let's write that down so what's the
first thing that
happened external
intercostals and diaphragm
contract and whenever these suckers
contract what
happens by the mechanisms that we
mentioned many times already it
increases the
thoracic cavity
volume okay cool well now let's see how
this affects these many
pressures if I can increase the thoracic
cavity volume let's think for a second
what can happen because technically this
is all connected to the chest wall right
as the chest wall is expanding and as
this is going down what we would expect
to happen here with this whole parietal
plural wouldn't we expect it to actually
expand a little bit also and to actually
go with the actual chest wall so let's
just PR pretend for a second that I
bring this one down I'm over
exaggerating it but it's going to be you
know for the purpose of making sense
here so again what's happening to this
parietal plural it's getting pulled
away and it would also get pulled away
with the chest wall as the chest wall is
expanding as all of this is expanding
what is happening to this actual volume
here well the thoracic cavity volume is
increasing so if the volume is
increasing what will happen to the
pressure according to Bo's law the
pressure will
decrease what is the pressure in this
area the int what is intra plural
pressure so the intra plural pressure
was originally what was it originally it
was approximately
about4 mm of mercury that that's what it
was at rest so we'll put put here on the
next to it
rest but then during the inspiratory
process the volume actually went even
greater than normal because now the
actual chest wall is trying to expand
it's pulling that parietal plural away
from the actual visceral plural and this
whole volume here is increasing
potentially right it will actually get
even more negative so the pressure will
drop even more to about what
point the pressure will drop so let's
say that here we show over here what the
pressure changes to the pressure will go
from4 millim of mercury to about six
okay so it'll drop down during the
inspiratory process to about
negative 6 millimeters of mercury and
this is
during
inspiration okay sweet
deal okay next
thing as this is expanding look what
happens
here because the thoracic cavity volume
is increasing not only is that allowing
for that to happen but what happens is
these lungs want to start expanding too
so because the lungs want to start
expanding something really cool happens
this guy right here what's going to
happen to him his his actual lungs are
going to start expanding also so the
visceral plura is going to start getting
closer and closer to the parial plur
right because again we have to remember
it is a potential space but when this uh
parial plur is being pulled away by the
chest wall what is it pulling with it
it's pulling with it the visceral plural
so now what we expect to happen with
this lung now and again we're going to
drag it out out here but as long as we
get the point look at this I'm going to
bring this sucker all the way down here
what did I just do to the
lung I increased the actual volume
inside of the actual lung so if I
increase the volume inside of the lung
what does that mean for the pressure
that means that the pressure goes down
oh man should make so much sense right
so again intra pulmonary pressure what
do we say that we denoted that as we not
as that as people right we call that the
people so the people was originally what
did we say it was about NE I'm sorry not
negative it should be zero millimeters
of mercury at
rest but then what happened what did we
say the visceral plura was getting
pulled with the parietal plura as the
long as the thoracic cavity volume was
increasing due to the external
intercostals and the diaphragm so as the
volume of this actual all these alveoli
start increasing what happens to their
pressure then the pressure starts
decreasing so what should it go to then
it should drop down to appr
approximately
about -1 so it only drops about one or
two it only drops about one or two
millimeters of mercury so we're going to
put here um let's just
put1 but again it can drop down about
negative 1 or -2 so it went down one so
we're going to put negative 1
millimeters of mercury during
inspiration
oh it should make so much
sense does to me somehow all right
now now that we've done that we should
understand how those pressures have
changed but what happens to the
atmospheric pressure does anything
happen with the atmospheric pressure No
it should stay the same right it should
stay the same so the atmospheric
pressure should not be affected let's
write that down though so the
atmospheric pressure it should not be
affected okay so it should still be uh
0o millimeters of Merc if we're
comparing it right but well just for
this case we'll keep it we'll keep it
here at 760 just for the heck of it so
we'll say 760 again millimeters of
mercury and specifically this
millimeters of mercury we could also say
um as a unit we could convert it to an
atmosphere right so 760 millimet of
mercury which is actually equal to one
atmosphere so that's the same okay what
about all these other dang pressures now
what about those okay let's get to that
second let's write down what happened so
far
thoracic cavity volume increased the
third thing that happened what happened
as the thoracic cavity volume increased
what happened the intra pulmonary
pressure what happened to his pressure
it decreased what happened to the intra
plural pressure the PIP IT decreased
okay the last thing to look at is what
happens to the trans pulmonary
pressure what happens to the actual
trans thoracic pressure and if you guys
want we could even say what happens with
the trans respiratory pressure so let's
go ahead and see what happens to all of
these pressures
here
okay well the transpulmonary pressure we
said was what let's write down here real
quick here was a b c we said that the
transpulmonary pressure was the
difference from a minus B which is the
intrapulmonary pressure minus the int
plural okay well now
1 and this is -6 let's write that down
so it went from NE it's - 1 mm Mercury
minus what 6 millimeter of mercury right
minus 6 but actually should be -6 should
be -6 so
-6 millimet of mercury so it's- 1 mm
Mercury minus -6 what is that equal to
about okay well if we have -6 right so
we're taking -1 + 6 so what does that
equal to that's equal to + 5 right so it
should be + 5 mm of mercury so it went
up a little bit but like I said again
the whole point here is I said remember
it actually went down by negative 1 it
can go by down by negative 1G -2 so if
it went down byg -2 what would that be
plus 4 millim mercy so it doesn't really
change significantly but it can change a
little bit in this case all right cool
let's do the next one the next one we
said was the difference between B and C
okay well the difference between B and C
is the difference from the intra plural
pressure in the atmospheric pressure oh
we said that this a trans thoracic
pressure let's write that puppy down so
the trans thoracic pressure is equal to
the int plural pressure which we said in
this case was
-6 millimeters of mercury minus what
zero millimeters of mercury and again
what do we say that this should be the
trans thoracic pressure should be equal
to the int plural pressure and the trans
thoracic pressure is -6 millimet of
mercury what does that imply that's a
good thing that means the chests are
actually recoiling outward and as the
chest is actually the chest wall is
recoiling outward what is it doing it's
pulling on this actual what it's pulling
on the chest wall and as it pulls on the
chest wall what happens to the volume in
this area it increases so that should
make sense because this negative is that
the chest wall is actually recoiling
outward that's
good and again for the heck of it we can
do this last one here let's do this one
in red which is the difference between a
to c and that was the trans respiratory
pressure and the trans respiratory
pressure is just going to be the what
intrapulmonary which in this case was -1
millim of Mercury right minus What minus
the atmospheric pressure which in this
case is 0 millimet Mercury and in this
case what does this tell us the trans
respiratory pressure is saying that air
is actually flowing in what direction
well it was negative one here so what's
our answer here our answer is -1
millimet of mercury that's the answer
what that means
is is that air must be flowing from the
atmosphere into the alveoli that's what
the negative 1 millim Mercury is saying
it's saying that the air is Flowing from
where the air must be flowing from the
atmosphere into the alveoli if it was
positive it would be the opposite it
will be flowing out of the actual alveol
line into the
atmosphere wow this is so beautiful all
right so let's write these things down
now everything that we have here again
transpulmonary pressure should now be
about positive five millim
Mercury and then the trans thoracic
pressure should be about 6 mm
Mercury and then the actual trans
respiratory pressure we said last one
was negative
1 mm of mercury and if we want to
reiterate it the int plural pressure
actually dropped down to about what it
dropped down to actually
-6 millimeter mercury and then the
intrapulmonary pressure or the intra
avolar pressure dropped down to about 1
mm
Mercury okay these are all the events
that are occurring in Inspiration now we
have to figure out okay all this is good
and well but does our lung stay like
like this no this is basically doing
what think about this what's the
pressure inside of the Alvi what's the
pressure inside of there okay was ne1 H
negative 1 in comparison to what
negative one in comparison to the
atmosphere so in other words we could
say this is 760 and what is another way
that I could write this guys 7 59 right
I could technically write this as
759 if I wanted to now what is that that
law again that actual law boils law or
not even I'm sorry not even boils law
just the law of diffusion the law of
diffusion things like to move from areas
of high pressure to areas of low
pressure so where would the air want to
flow the air would want to flow inwards
and so
now look what happens here air starts
flowing inward as the air starts flowing
Inward and more and more and more into
the lung it'll continue to flow from the
atmosphere into the actual lungs until
the intrapulmonary pressure at the peak
point of inspiration goes until it
actually equals the atmospheric pressure
so let me say this one more time here
let me actually put it over here and
pink afterwards to write this over here
to make sure that we're clear let me
explain it one more time before I write
it
down this is negative 1 so it's 759 in
here it's a lower pressure out here is
high higher pressure things like to move
from high pressure into areas of low
pressure as this air is Flowing it's
flowing from areas of high pressure to
low pressure it will continue to flow
from the atmosphere into the actual
lungs or the alvioli in this case until
the pressure in the alvioli equals the
pressure in the atmosphere what is the
pressure in the atmosphere 760 mm of
mercury so it's going to go until it
equals 760 mm of mercury and that is
going to be at the peak point of
inspiration so while that happens when
all those events are happening when our
muscles are Contracting and all those
events the whole point is to suck air in
by pressure gradients so this will
eventually cause the intrapulmonary
pressure to equal if we say it's 760
what does that mean so what 760- 760
zero but again just so that we're clear
again what would that actually be if we
put it in the larger numbers it would be
760 because it has to reach equilibrium
with the atmosphere so this is what will
be at the peak of inspiration and then
whenever we get ready to go into ins I'm
sorry whenever we get ready to go into
expiration which we'll do in the next
video you'll see how all of these
pressures are changing again so amazing
okay all right guys so in this video we
talked a lot about the inspiratory
processes specifically with respect to
the whole mechanics of breathing okay in
the third video the next video we're
going to see exactly how all of these
events are happening again but in
Reverse specifically in expiration all
right ninja ner I'll see you soon
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