Alveolar Pressure and Pleural Pressure

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Video Summary:
Understanding of lung mechanics starts with understanding pressures in respiratory system. In this video I have explained pleural pressure and intrapleural pressure (or simply pleural pressure). Alveolar pressure is pressure in alveoli. When no air is moving and glottis is open, entire airway including alveoli are in balance with atmospheric pressure. So pressure is 0 cm of water. This is the situation just before starting inspiration or expiration. During inspiration it falls to negative value to suck air from atmosphere and during expiration it becomes positive which drives the expulsion of air. Pleural pressure is negative due to opposing force by lung and chest wall on pleural space. Elastic recoil of lung pulls the pleura inward and elastic recoil of chest wall pulls it outwards. Drainage of lymphatics also contribute in vacuum. In this discussion I haven't touched transmural pressure.
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DISCLAIMER: This video is for education purpose only. Although every effort is made to ensure accuracy of material, viewer should refer to the appropriate regulatory body/authorised websites, guidelines and other suitable sources of information as deemed relevant and applicable. In view of possibility of human error or changes in medical science, any person or organization involved in preparation of this work accepts no responsibility for any errors or omissions or results obtained from use of information in this video.

[@babygurll7]

This really helped my understanding of intrapleural pressure and why its negative and more negative at the apex! Thanks sooo much!!

[@NonstopNeuron]

Welcome 😊

[@nora4784]

This is beyond helpful thank you very much 🙏🏼

[@AmitavaGarai]

That really was so helpful ❤

[@huenhuluu]

this is amazing, I really got stuck w/ what the book writes but this video explained everything well, thank you so much

[@aimenkamara4297]

Thank you, you made it much easier💖

[@DR_YAZZ]

I was wondering how does the pleura works and keeps the lungs from collapsing, thanks to ur video now i understand . So thank you 🙏❤️

[@GraemeEdwardSmith]

Good simplified diagram. Thank you.

[@syedmohammadaanasfarukh890]

What a guy. Respek. Great video mate. Helped a lot.

[@aznfresh4]

Thank you so much. amazing visuals and easy to understand.

[@alaahroub3790]

thanks alot! I was struggling with these concepts but this video made it clear and easy :)

[@NonstopNeuron]

Glad it helped!

[@musaddiqrauf4093]

Love you sir,,, you made it very easy 💙

[@zeeshantarapurwala6852]

Concise and to the point. Thank you so much

[@NonstopNeuron]

You're welcome!

[@arsalanazhar3340]

INCREDIBLY AMAZING, u made this so easy. THANKYOU

[@NonstopNeuron]

Thank you very much. You can support by sharing the videos 😊

[@FA-vg3le]

Simple and clear
Keep going 👏

[@safaahegazy9976]

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Thank you

[@magdynasr6639]

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[@raninetahir3307]

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[@husseinelkhodery7129]

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[@zainab-jg9vl]

Good job 👏🏼 ❤

[@nooralaa4466]

Many thanks

[@alfa4305]

Super,thank you❤

[@atem2302]

I agree. excellent.

[@anshulkohli693]

Hats off to u what an explanation

[@AbuTalhaAdor]

You are great sir... Thank you ...take love from Bangladesh ❤❤

[@idreeskhanachakzai6637]

this really helped me thank you soo muchhhh
i was struggling with the concept now got it cleared Alhamdulillah!

[@NonstopNeuron]

Most welcome

[@sumu_0036]

Thankyou so much ❤
So far, this is the best channel for physiology.

[@NonstopNeuron]

Most welcome

[@nisansalaperera3139]

thank you

[@kath7012]

THANKS ALOT!!!!! I like your explanation and graphic. keep up the good work

[@NonstopNeuron]

Thank you

[@muhammadtalhaqureshi6734]

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[@moiznauman5121]

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[@anasrahim526]

Sir thankyou soo much
Very helpful👍

[@minarichowdhury6889]

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[@MarcusFriend]

This was amazing!! Thank u so much!! Didn't take too long and VERY VERY CLEAR

[@NonstopNeuron]

Glad it helped!

[@sushmarangu4113]

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[@NonstopNeuron]

Thank you so much. We are creating videos the fastest we can to cover all the topics and subjects the earliest.

[@lokipoki3640]

My lecturer telling such a complicated story for this .🥲

[@user-pc9si7wo7o]

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[@NonstopNeuron]

Most Welcome

[@patrickcheng4248]

covered an hour lecture in a few minutes thanks

[@NonstopNeuron]

That's the main purpose behind the channel. Thank you 😊

[@PRINCESSTEOVILCABALHUG]

Thank you so much!!!

[@NonstopNeuron]

You're welcome!

[@jonathanfargalla5427]

Thank u

[@uzumaku_naruto]

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[@NonstopNeuron]

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[@madmedicos786]

Keep it up sir ,,,we need ur crystal clear concepts for second yr MBBS also... ample of thanks sir🤗

[@NonstopNeuron]

Sure. We already have many videos for the second year. And will continue to make.

[@petrebadea7694]

amazing !!

[@NonstopNeuron]

Thank you

[@retromate]

Best explanation

[@NonstopNeuron]

Thank you 😊

[@tomcruise9317]

Any importance in keeping plural pressure negative

[@Faithhhh110]

Pls make a video on transpulmonary and other trans pressure

[@srabonimim2306]

Great video 🤌

[@NonstopNeuron]

Glad you enjoyed

[@khadijah3343]

This was really good!! I just have one question- at 2:42, did you mean pleural pressure is considered uniform from apex to the base of lung?

[@NonstopNeuron]

yes, from apex to base

[@khadijah3343]

@@NonstopNeuron thank you!

[@Dr.Aakanksha]

Sir from base to apex pleural pressure is decreasing ( as more
-ve pressure at apex and less -ve at base)
but usually from base to apex pleural pressure is considered uniform
Correct me if i am wrong ?

[@plcdatvl]

thanks for your video, pls make the video about how brain can control the operation of the lungs?

[@NonstopNeuron]

Noted

[@dreamer8045]

Woah❤

[@kevina5018]

one of the best videos i have seen about this topic bravo!

[@pansareddy4031]

tanq very much sir

[@NonstopNeuron]

You are most welcome

[@johnadrianurbano1976]

omg I love you

[@fastratedabc1903]

Thanks sir carry on

[@NonstopNeuron]

Most welcome

[@paolam.3571]

Nice video. I just have one doubt. The pressure inside the pleura is negative bcs of the opposing forces of the lungs and the chest wall. But when we inhale both chest wall and lungs expand outside in same direction so i didn't understand that. Hope you can respond🙏

[@NonstopNeuron]

When inspiring, our efforts expand chest wall, that creates even more negative pressure in pleura i.e vaccum is created. As nothing except lungs is there to fill that vaccum, lungs expand

[@NonstopNeuron]

In case of injury when air can enter the pleura, air fills that vaccum and lungs can collapse due to its tendency. That's what happens in pneumothorax.

[@mohammedbilal8463]

@@NonstopNeuron so at the moment when lung expand , doesn't the intra pleural presuure increases and goes back to -5?

[@NonstopNeuron]

Yes.. expansion of lungs balances the decrease in intra pleural pressure during inspiration.

[@somarajuraju2970]

Super sir

[@NonstopNeuron]

thanks!

[@gostudyrahi7272]

Can u explain what will happen to lung in pneumothorax? Will both chest and lung collapse or just one of them

[@NonstopNeuron]

They both try to take their resting position. So lung collapses because of inward recoil of its elastic tissue. And chest wall expands because pleura can no longer pull it inward. Watch this video:
czcams.com/video/H5W9PrLd3MI/video.html
It will help with underlying concepts.
I hope it helps.

[@gostudyrahi7272]

@@NonstopNeuron thank u so much 🥺♥️

[@medicalscience1528]

What does mean of ' of water ' ? I really did not get it. Plz explain or someone plz explain it. Else what a great lecture thanks a lot. Stay blessed . You really helped so many huamns in such great way.😊

[@NonstopNeuron]

It's a unit of pressure. It is said that way...

[@NonstopNeuron]

en.m.wikipedia.org/wiki/Centimetre_or_millimetre_of_water

[@medicalscience1528]

Ok. Thank you 😊😊

[@medicalscience1528]

@@NonstopNeuron Can you answer one more of my.question ...
in the alveolar and pleural ( or overall pressure in lung we have been studying )
does positive pressure mean , we have more air in alveoli so that in the lung than outer atmosphere ?
And negative pressure mean that inside the alveoli air is comparatively lesser ? So lesser the pressure is .
And that is the reason that air moves from outer atmosphere to inside lung as from higher to lower concentration ? During inspiration .
And from lung to outward as in expiration ?
Thank you.

[@NonstopNeuron]

Absolutely yes.
Because you used the word "concentration" later on, I am assuming that by more or less air, you mean more or less air density, and not volume. Just mentioning this because volume difference does not drive movement. But you already don't seem to have that confusion. So in short, the answer is yes.

[@roaajafar6218]

Can you explain how the intrapulmonary pressure return back to zero at the end of inspiration and expiration 🙏🏻

[@NonstopNeuron]

during inspiration/expiration, air moves due to pressure difference between atmosphere and in respiratory tract. This happens till there is pressure difference. Evantually the pressure inside the tract equilibrates with that of atmosphere. So we have 0 pressure at the end of inspiration/expiration.

[@fasiurrehmankhoso3289]

It cleared my concept but there is one question sticking in my mind that if pleural pressure has been decreased by expansion of chest wall then it must increase a little bit due to expansion of lung during inspiration cause visceral pleura comes a little bit closer to parietal pleura than it was before.

[@NonstopNeuron]

How do I explain...!!! Don't over think. Think in terms of cause effect sequence. And remember that everything is happening simultaneously but to understand them better, we think in terms of cause effect sequence. I hope you figure out yourself by this hint.

[@tomcruise9317]

When we inspire chest wall increaae intra plural pressure become -2 to-5 but when this happen lung volume too increase so we cant maintain the -5 pressure i.e trans pulmonary pressure which was 0-(-2) =2 initially after inspiration (before air entry) 0-(-5)=5 so this 5 trans mural pressure will make the lung to inflate and the intra plural pressure will get decreaaed to 2 ....butvin book its at end of inspiration intra plural pressure will be 5 is given can you explain

[@NonstopNeuron]

Values may vary from book to book. But your overall understanding seems to be right, which is more important.

[@tomcruise9317]

@@NonstopNeuron no its not about value im asking about the concept during end of inspiration intraplural pressure is -6 mmhg as per book (initially -2) but i am asking how can it happen if chest wall increases then negativity intraplural pressure is increased but this negative plural pressure will cause the lung to inflate as pulmonary pressur is 0 i mean this inflated lung will nutralise the negative pressure to intial negative 2

[@Shawtyy459]

What will happen if negative intrapleural pressure is not maintained even during exhalation ? Lungs will collapse but how ? Is there air in pleural cavity that will escape when negative pressure is not maintained ? Please help

[@NonstopNeuron]

Whenever lungs collapse, its due to their elastic nature. There is no air in pleural cavity. However air might enter in pleural cavity in chest injury. In that case the negative pressure is lost (as pleural cavity comes in contact with atmospheric pressure due to injury) so the lungs collapse. I hope it helps.

[@srinivasan7892]

How interpleural pressure remains -7.5mmhg when visceral pleura also expands during inspiration??? Please answer this..

[@fasiurrehmankhoso3289]

That's my question as well and I am searching this for several days

[@DrXan-om2lk]

The intrapleural volume has increased comparatively , as inspiration is an active process , which includes movement of chest walls and muscles .
The chest wall has moved further away , hence the increase in volume and decrease in pressure .
According to boyles,
P=1/V

[@DrXan-om2lk]

The movement of chest wall is more compared to the expansion of lungs .

[@cristaku9259]

Thanks❤🌹

[@NonstopNeuron]

You're welcome 😊

[@nrutyageethika]

Very nice sir..... thank you

[@NonstopNeuron]

Welcome 😊

[@leenalsayeh206]

THANK YOU ! but I have a question ... why do the lungs expand when the interpleural pressure becomes -6 during inspiration ? doesnt it have collapsing force ?

[@NonstopNeuron]

The pleura is attached to ribs, kind of fixed to it. And it surrounds the lung. So negative pressure in the pleura sucks the lung from all around outside the lung. So lungs expand. I hope it's clear now

[@NonstopNeuron]

Not normally. You might be confusing it with alveolar pressure.

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[@TM-lf6os]

Good video, but your accent can be a bit hard to understand. Mostly though, it is the microphone quality. It sounds like you are in a bathroom! Good video but hard to understand.