Lung compliance Physiology | Hysteresis in lung pressure volume curve | Respiratory physiology

[@AkashS007]

The best one out there.

[@PhysiologyOpen]

Thank you 😊

[@fahmincv5545]

Yep 😂

[@AkashS007]

@@fahmincv5545 hello there😁

[@julianalacerda4220]

This video just made my day! I finally understood these concepts. Thank you so much!

[@PhysiologyOpen]

Glad you liked it…most welcome

[@kca7695]

Mam I have struggled very much to understand why compliance is more in expiration than inspiration U have explained it beautifully at 6:15 THANK YOU MA'AM

[@PhysiologyOpen]

😊...always happy when a student understands the concept..Physiologyopen task fulfilled

[@abhishekjangra21]

Thankyou ma'am Jaise aap concept explain krte ho toh topics samaj me aata hai 🙏🏻🙏🏻🙌🏻🙌🏻

[@PhysiologyOpen]

I am so glad !!

[@chandinireddy2345]

Really loved your efforts! No one would thought of explaining this topic through phusics, you really did a great job mam ❤️❤️

[@PhysiologyOpen]

Thank you

[@patriciac.i.o.6362]

I absolutely loved how you explained this super important concept! You went all the way to physics to make it super comprehensible! Thank you so much for sharing your knowledge!

[@PhysiologyOpen]

Thank you so much…I feel if we skip the physics part people find physiology confusing…I am glad my efforts worked

[@samayaagarwal3475]

Ma'am your videos are really helpful. Plz make videos on all the imp and difficult topics of physiology which are left as soon as possible .🙏

[@PhysiologyOpen]

Let me know all the topics you want videos on

[@samayaagarwal3475]

@@PhysiologyOpen ma'am plz make a video on smooth muscle action potential (including spike wave and slow wave etc topics also) and also plz explain the difference between action potential of nerve,smooth muscle,skeletal muscle,cardiac muscle in detail🙏

[@PhysiologyOpen]

@@samayaagarwal3475 sure...already made videos on neuron, and cardiac action potential..mentioned about skeletal muscle action potential in the video on phases of neuron action potential Will do one on smooth muscle soon

[@samayaagarwal3475]

@@PhysiologyOpen Thank you so much ma'am🙏

[@arshithgowda8728]

@@PhysiologyOpen mam do a video on (cerebral blood flow regulation)

[@jaydentjmuso]

You explained this so well, such a life saver! Thank you heaps:)

[@PhysiologyOpen]

You're very welcome!

[@hesham-wu9ql]

Compliance is not about expansion, it's about deformation (STRAIN)produced per certain amount of STRESS. In case of lung physiology the deformation (STRAIN) is measured in change in volume/original volume. STRESS is that which causes that STRAIN (change in volume) and is measure of Trans pulmonary pressure [intra alveolar pressure(IAP)-intra pleural pressure(IPP) ] The actual formula for compliance is strain/stress. Strain= change in volume/original volume Stress= trans pulmonary pressure Now into your question Even after expiration lungs still have functional residual capacity of 2500ml air inside all alveoli. So even before inspiration the volume of air in lungs is 2500 ml which is V1 Now after normal inspiration (tidal volume) of 500ml the total volume of air now in lungs is 3000ml = V2 Change in volume= V2 - V1 That equals to (3000 - 2500)=+ 500ml That positive sign indicates the stress is tensile and is stretching in nature. Now come to strain STRAIN = change in volume/original volume(V1= 2500ml) Calculate it STRAIN = 500/2500 = 1/5 Now STRESS= trans pulmonary pressure at end of inspiration { Tpm} Tpm = IAP - IPP At end of inspiration IAP = 760mmhg IPP = 754 mm hg So Tpm = 760 - 754 Tpm = 6mm hg Now come to compliance C = strain/ stress C = 1/5×6= 1/30 [ml/mmhg] The inference is for a stress(pressure) of 30 MMHG the strain (deformation or volume change) is 1ML. So for inspiration the lung compliance is 1ml per 30 mm hg Now let's calculate for Expiration Before expiration that is at the end of inspiration the volume of air in lungs is 3000ml Now V1= 3000ML And now stress is elastic recoil of alveoli which increase pressure and produce change (deformation) After normal expiration (T.V) of 500 ml the final volume V2 is 2500 ML So change in volume is - (V2 - V1) The negative sign indicates the elastic recoil of alveoli is of compressive stress So change in volume is - (2500 - 3000) U will get 500ML Now for strain = change in volume/ original volume STRAIN= 500/3000 = 1/6 (no units) Now for stress (Tpm) Tpm at end of expiration is IAP- IPP IAP at end of expiration is 760 mm hg IPP at end of expiration is 758 mm hg Tpm = IAP- IPP Tpm = 760 - 758 = 2mm HG Now for compliance C C = strain/stress = 1/6×2 = 1/12 [ml/mmhg] The inference is for a stress of 12 mm hg the strain is 1ml So during inspiration for producing a change in volume of 1ml u need 30 MMHG But in case of expiration for producing a change of 1ml u just need 12 MMHG. Final take = for a very little stress if we produce more change it has more compliance Compliance of lungs is higher in expiration than in inspiration bcoz in expiration a less stress(pressure) produces more change in volume That's it

[@MilkMocha-jh6pp]

Mam you have explained a difficlt concept in a simlpe way and beautifully.thanx

[@PhysiologyOpen]

Thanks and welcome 😊

[@matysteven]

Por fin, después de 19 años de mi vida, he aprendido a interpretar un gráfico de este tipo. Te agradezco muchísimo, de verdad, greetings from Spain, new subscriber :D

[@PhysiologyOpen]

Language of love❤️

[@shivangirambalibaghel]

Best lecture 🎉🎉🎉🎉

[@PhysiologyOpen]

Thank you 😊

[@kaniskal8900]

Thank you so much .your explanation really helpful ..

[@PhysiologyOpen]

So glad

[@gongallakamalakar7525]

Thanks medam for clearing the concept in a simple way , glad to have teacher like u ♥️♥️

[@PhysiologyOpen]

Thanks and welcome 😊

[@saniasultana7141]

Thank you soooooooo much for giving us such type of quality explanation❤❤❤❤👍👍👍

[@PhysiologyOpen]

So so glad

[@subhanishaik-fb5qj]

Mam 🙏🙏🙏you saved my exam tomorrow ❤❤❤

[@PhysiologyOpen]

Awesome 😊

[@ananyagupta9730]

Wow my mind is blown. Thank you

[@PhysiologyOpen]

Awww...so happy😊

[@studybite10M]

best explanation 😍😍😍😍 thank you mam

[@PhysiologyOpen]

My pleasure

[@farahshaikh6327]

Thankssssss mam for suchhhh a crystal clear explanation,thnks a lott👍

[@PhysiologyOpen]

My pleasure

[@shaimamerghani8300]

Thank you very informative 👍 👏

[@PhysiologyOpen]

Glad it was helpful!

[@livingmyself2232]

Its really awesome mam. The concepts are very clear. So helpful

[@PhysiologyOpen]

Glad you liked it. Keep learning 😊

[@mhassan5933]

Nice 👍

[@PhysiologyOpen]

Thanks ✌

[@ganeshvel4798]

Awesome mam

[@PhysiologyOpen]

Thank you! Cheers!

[@kiranjitsidhu6114]

Mam beautifully explained.Mam so both surface tension & elastance play a role in hysteresis??

[@PhysiologyOpen]

yes..but mostly surface tension

[@Destinyschild777]

Wow Mam thank you so much

[@PhysiologyOpen]

Pleasure ❤️

[@shaharpitkirankumar2557]

Very beautiful lecture 😊

[@PhysiologyOpen]

Thanks a lot 😊

[@AK-yu4tf]

Mam thanks u very much for your lecture

[@PhysiologyOpen]

It's my pleasure

[@faizmudassir5011]

awesome

[@PhysiologyOpen]

Thanks

[@sanasabir1925]

Well explained ❤

[@PhysiologyOpen]

Thank you 😊

[@rubanu7066]

Thankyou mam❤🙏

[@PhysiologyOpen]

Most welcome

[@DRBHUPATHI]

mam would be really helpful if you could make a vedio on static ,dynamic compliance

[@PhysiologyOpen]

Yeah that was on cards...but then got shifted to acid base balance...will try to do it in near future

[@sagarsrivasatava3004]

So good😍😍😍😍

[@PhysiologyOpen]

Thanks 🙏

[@kiranjitsidhu6114]

Mam is this concept there that during inspiration surfactant concentration decreases in alveoli & opposite happens during expiration?

[@PhysiologyOpen]

Yes…because in inspiration alveolar volume increases(surfactant amount remains same - but it’s concentration will decrease

[@kiranjitsidhu6114]

Thankyou 🎉​@@PhysiologyOpen

[@meyercaamanoamaliateresa4595]

buenísimo muchas gracias!

[@PhysiologyOpen]

Thanks

[@AdityaSathya]

What exactly is specific compliance ma'am?

[@PhysiologyOpen]

Compliance normalised for lung size - for comparison of compliance in different lung sizes . Let me say just like cardiac index is cardiac output divided by body surface area

[@ofabhay]

Mam fromwhere can we get ur notes🙏

[@PhysiologyOpen]

Download Physiologyopen app

[@shaziafarooq7804]

Mam, both compliance and elastic recoil depends on elastic fibres, then why they are inversely related to each other

[@PhysiologyOpen]

Compliance leads to stretch...elasticity to recoil...

[@govindsharma9517]

Ma’am 🙏🙏

[@PhysiologyOpen]

😊❤️

[@seema9875]

During inspiration intrapleural pressure is less negative not same as inspiration than transpulmonary will be different

[@PhysiologyOpen]

Can you quote the time in video please

[@medicalbiochemistry_]

Nice

[@shaziafarooq7804]

Mam,please have a video on flow volume curves

[@PhysiologyOpen]

Sure will do

[@shaziafarooq7804]

@@PhysiologyOpen thank you so much.. Mam

[@PhysiologyOpen]

Flow volume loop - Full concept: kzbin.info/www/bejne/e3nLoouCnKaZmJY

[@shaziafarooq7804]

@@PhysiologyOpen thank you so much mam

[@PhysiologyOpen]

You are welcome 😊

[@ASHISHCR7VK18]

How low and high lung volumes make lung stiff(less compliant)

[@PhysiologyOpen]

When it reaches high lung volume, the tissue is at its limit of stretching…at low lung volumes, it’s just the property of the tissue that’s it’s difficult to stretch

[@ankanbiswas1527]

Mam during expiration surfactant concentration increase and decreases surface tension , so can i say during expiration lung compliance is more than lung compliance in inspiration!!? Is during expirationcan we use the term compliance???

[@PhysiologyOpen]

It’s experimental…when we take out air from lungs , how much pressure change occurs (delta V/ delta P)…in clinical scenario - decreased compliance means decreased filling and also increased recoil thus decreasing TLC, VC and also FRC

[@why.............]

3.Condition in which FRV decreases

[@nithinkrishna9861]

Ma'am one doubt.. If the intra plural pressure changes from -5 to -8cm H20 during inspiration approximately 500ml of volume will enter the lungs(tidal volume). So if the person has open chest cavity ,so that the pleural pressure is equal to atmospheric pressure ,then howmuch change in pleural pressure will be there to achieve some tidal volume during inspiration

[@habeebolalekan8373]

With open chest cavity, every inspiration leads to seeping of air into the pleura cavity through the wound and since the tissue at the sight of injury act as a flap, the air doesn't come out during expiration. This increase the intrapleural pressure thus preventing the lungs from expanding ( collapse). To achieve tidal volume, I feel one need to perform thoracostomy.

[@logeshram5244]

Mam how (1/thoracic wall compliance)= total compliance - ( 1/ lung compliance) is derived???

[@PhysiologyOpen]

I think it’s not incorrect 1/total compliance = (1/lung compliance ) + (1/thoracic cage compliance) So by rearranging the equation we will get correct derivation Compliance of lung and thoracic cage are not simply added because mostly their compliances oppose each other

[@logeshram5244]

@@PhysiologyOpen Mam then, how this inverse relations came???

[@PhysiologyOpen]

It’s like if you have read about series and parallel circuits in physics…when resistors are in series they are added up but when in parallel , they are added up with this inverse relationship. When capacitors are in series they have inverse relationship (something like that,I need to check)…similarly after experiments on lung separately , thoracic age separately , and both combined…they found certain values and this equation best describes those values

[@logeshram5244]

Ok thankyou mam

[@lekhareddy2110]

What is the answer for 3rd question

[@PhysiologyOpen]

In cases where lung volumes themselves are lower e.g. in case of children..stretchability is normal but lung compliances are low..so for comparison we need to actually calculate specific lung compliance

[@lekhareddy2110]

@@PhysiologyOpen tq mam

[@PhysiologyOpen]

Keep learning

[@vineetkumarpandey3003]

I read that Elastic recoil is not the reason for hysteresis as you have explained. Isn't it the surfactant which is responsible for varying pressure-volume curves during inspiration and expiration ?

[@PhysiologyOpen]

Yes experiments have shown when surfactant is removed, hysteresis almost disappears..yes but almost

[@vineetkumarpandey3003]

@@PhysiologyOpen okay ma'am

[@PhysiologyOpen]

Questions on lung compliance: 1. Why is the first breath of a newborn so difficult ? 2. What will happen to lung compliance if some alveoli collapse (atelectasis) 3. Can you think of a condition in which lung stretchability is normal but when calculated- lung compliance will be low. (Hint: we use specific compliance in these cases)

[@tusharsaini4177]

1. because during birth the lungs are not proper functional so bay uses his all muscles for breathing that is result in first cry 2.may be complinace will decrease as due to increase in collapsing pressure 3.i don't know waiting for your response mam whether my answers are correct or not THANK YOU for all your videos..!!

[@PhysiologyOpen]

@@tusharsaini4177 1. Lungs are not proper means: it has to be related with lung compliance...Think about what is the lung volume at the beginning and how is compliance related to initial state of lung volume..For 2nd option also, we have to think with respect to lung volume and how does it affect lung compliance... 3. Hint: what will happen to compliance if a person has only one lung... ? will stretchability be normal ?

[@tusharsaini4177]

@@PhysiologyOpen so 1.initially compliance will be less as there is less volume 2. 3.may be in diff pathological conditions mam for the 2nd i am not getting the point..that what we hv to ans

[@PhysiologyOpen]

for second... if alveolai collapse, lung volume will decrease, decreasing the lung compliance. That's one reason how residual volume is helpful since if with every breath, we have to inflate the lungs with initial zero lung volume, it will take lot of effort since compliance of lungs is very less at low lung volumes...

[@davidvincentr8725]

Q3 . Unilateral pneumothorax

[@077insiyanoorbhai4]

Ma’am why is the compliance of the lung alone is more than total respiratory compliance, when the lung has a recoil tendency to collapse .

[@PhysiologyOpen]

Lung compliance and thoracic compliance are almost same...however the compliance of both together is calculated as 1/Ctotal = 1/C lungs + 1/C thorax...hence total comes lesser

[@077insiyanoorbhai4]

@@PhysiologyOpen thankyou ma'am , understood

[@shailkumarjain]

In Graph at 6.21, in expiration limb, initially for a greater transpulomonary pressure change volume expired is very less but since elastic recoil of lung is big here, more volume should change relatively than to later part of expiration. Why is it not happening ? Kindly advice some reason. Thank you.

[@PhysiologyOpen]

You need to see change in transpulmonary pressure (not at a point but change) vs change in volume

[@shailkumarjain]

@@PhysiologyOpen thank you for reply. yes i am asking about initial change in volume over pressure change of expiration limb. The curve is less steep at initial phase of expiration. Why ? 🙏

[@PhysiologyOpen]

Not sure, may be the properties of the tissue are like that..or may be inertia

[@moumitabiswas883]

Mam could not understand hysteresis

[@moumitabiswas883]

In the graph,during inspiration and expiration, trans pulmonary pressure change is not very distinct. It will be beneficial if you put some value

[@sathishkalivela926]

Nice explaination but little fast

[@PhysiologyOpen]

Ok. Thanks for feedback.

[@babybear4]

I love you maam

[@PhysiologyOpen]

Ha 😊

[@shaziafarooq7804]

Mam, when there is no inspiration Or expiration -5 pleural pressure keeps alveoli at 0 atm pressure, then how during expiration the same pleural pressure allows alveoli to reach +1

[@PhysiologyOpen]

Air is more in lungs due to inspiration With the relaxation of muscles, the same air occupies lesser volume in lungs, increasing the pressure

[@shaziafarooq7804]

@@PhysiologyOpen thank you so much... Mam ur videos are really based on concepts

[@PhysiologyOpen]

@@shaziafarooq7804 Thanks

[@deepanshuvats2211]

Ma'am what is the relation between surfactant and hystersis?

[@PhysiologyOpen]

Absence of surfactant causes almost disappearance of hysteresis, as per experimental evidence

[@deepanshuvats2211]

@@PhysiologyOpen Thank you ma'am

[@PhysiologyOpen]

My pleasure

[@sagargupta8015]

❤

[@PhysiologyOpen]

😊