What is preload? | Circulatory system physiology | NCLEX-RN | Khan Academy

[@rawdonwaller]

Beautiful. Understanding this small amount of extra detail makes 'preload' that much more comprehensible to me. KZbin and Khan are resources par excellence.

[@ldyprinz]

I have been a nurse for a long time and this was one of the best explanations I have ever seen.. Thank you

[@chc892]

PRELOAD = "WALL STRESS" (units = kg/m*s2) i.e. the same units as Pressure Original Laplace's Law: "Wall Stress" = (P * r)/2*h *So if you multiply and divide Pressure by the same units (meters) you just get Pressure units back!! Tension units = (kg/s2) *Thus Wall Stress = Wall Tension/Wall Thickness *These units are also used by the spring constant k in Hooke's Law Finally Laplace's Law can be used within the ventricle to calculate Preload: Preload =(left ventricular end diastolic PRESSURE * left ventricular end diastolic RADIUS)/ 2* left ventricular wall THICKNESS *Therefore, Preload is a NEW pressure in the left ventricle that wall thickness and inner radius have changed

[@Poonamgupta-wn6ni]

Khan academy is undoubtedly the one proving every brick (basics)is important if the wall (concept) has to be stable(clear)!I hope one day I will be a part of it☺

[@palaknehra]

Man….this channel is the best thing that’s happened to me ❤

[@lizakerr6323]

You are incredible breaking down difficult pathophys concepts! Thank you very much for helping me understand better. I am currently in nurse practitioner school and highly recommend Khan Academy!

[@sophiekreynolds1]

"another term that people use all the time all the time is... PRELOAD... preload i think it's really important to define....preload is NEITHER pressure nor volume... it is equal to the WALL STRESS... Left ventricular wall stress, at END DIASTOLE." perfect

[@haitianhottie101]

I understand that preload deals with Laplace's law but you spent more time on that that the actual concept of preload in itself.. still an alright video though just would've preferred further explanation

[@ramzeschavez]

Preload = Frank- Starling

[@VickiBee]

This stuff makes me grateful for Omnimedic, the thing they created to do the calculations FOR us; because in an emergency, every second counts. I can't do these calculations in my head like the doctors actually HAVE done. If I could, I probably would have made it into PreMed school instead of just being a paramedic. If I hadn't actually been living with a doctor when I became a paramedic, I never would have made it through capnography.

[@kalldesk123]

wow...Thank you Sir! you are Awesome

[@mariabelinska2797]

Thank you very much this is really impossible question at my faculty.

[@wiamalbouzidi8362]

thank you so much ! helping us in corona time

[@hvn81]

Fot the very first time somebody knows what preload is!! LOL. Thank you

[@mishganfatima2930]

😂😂

[@moragwa]

wow definately my new favorite teach SUBSCRIBED!!!

[@oscarquiroz3324]

EXCELLENT! Thank you for a very clear description of a very fuzzy subject I have been able to find. You are an outstanding instructor.

[@TheBetadecay]

what do you think he was trying to teach? The title is "What is preload". I think knowing how to calculate Preload is essential. People from different disciplines, including engineering and physics, will be looking at PV loops and dealing with preload. I think the math is very appropriate.

[@fastbreather]

Isn't compliance change in volume/ change in pressure? Please enlighten me on this.

[@andreal9458]

Isn't Compliance change in volume/ over change in pressure? (V/P), not P/V, as the video has indicated?

[@local5ab]

thanx dr rishi.

[@ezzo911]

thanks alot

[@JR-ou2el]

Pressure and volume are inversely related. Yet, the graph shows a direct or positive correlation between the two. How can that be right?

[@pangeyi]

Good job on explain preload.

[@lbryanmillanl]

Because it´s about the volume of the content, not the container

[@jeffreagan2001]

You describe elastance as the slope of the EDPVR. So shouldn't you describe it as the change in pressure/change in volume rather than P/V or in calculus terms the derivative of the EDPVR?

[@nazmulurrahmannazmul2681]

thank you sir for it was an excellent lesson and it helped me a lot.

[@tigerswallowtail6012]

Love these vids

[@riteshchaurasia8016]

How does end diastolic volume ant point A increases to 125 to 150ml to point B ..plz explain..!?

[@PG0355]

Excellent lesson

[@LubaNikit]

r is R_{IN}, not R_{TOT}

[@Tomevone]

how can u assume the left ventricle to be spherical. since u applied "4/3 π r3"???

[@heartshunter]

You have to change the video title to Cardiac Preload.

[@myh4you]

Uhm,preload is not wall stress,that's afterload..or at least that's what my cardiology book says..if Preload is wall stress then what is afterload all about ? Laplace has nothing to do with preload.

[@brandonderuiter9157]

+Mihaela Țolea Maybe pre-load and afterload are wall stress during different parts of the cardiac cycle

[@GoToHellHermen]

Afterload is the load against which the cardiac muscle exerts its contractile force. (i.e. the pressure in the arteries)

[@YanSimonMusic]

I'm pretty sure wherever you said "Elastance" you actually meant "Compliance".

[@YanSimonMusic]

Just finished a physiology course in uni, we used compliance when talking about the CVS, never elastance.

[@ghazwanalwan4303]

Compliance is different from elastance.

[@dramaaddict2011]

no. compliance is V/P

[@drownedingames488]

Elasticity is the inverse of compliance. A vessel that has high elasticity (a large tendency to rebound from a stretch) has low compliance.

[@mariaskf1]

To the best of my knowledge this is afterload and not preload...

[@bentduck]

no, Maria, Khan is correct.

[@manel7480]

Afterload is the pressure the LV has to face when contracting an ejecting blood, not before that...

[@GoToHellHermen]

Afterload is the load against which the cardiac muscle exerts its contractile force. (i.e. the pressure in the arteries)

[@ericerickson4876]

This explanation was so over talked with unnecessary information that I would give it 4 thumbs down.

[@bradschroeder7705]

Wasnt helpful