Normal Acid-Base Regulation (ABG Interpretation - Lesson 2)

[@aleo6480]

As a MD, I need to thank you deeply for providing these very useful videos for reviewing and re-studying fundamental topics. Cheers from Italy

[@tesfaymoges2754]

These videos are made more than 10 years ago, they are still fresh. I can't thank you enough for these fine presentations.

[@rawdonwaller]

I found this to be a well-rounded, balanced (basic science and clinical considerations), well-paced lecture. I particularly appreciated the asides, e.g., 'acid' having negative connotations. I believe such asides make a lecture--any lecture, not just this one--more interesting, for several reasons. Good job.

[@StrongMed]

I'm glad you enjoyed it! The music is the La Réjouissance movement from Handel's Music for Royal Fireworks.

[@StrongMed]

...I didn't mention their hypoxemia detecting function in this lecture because I was trying to focus on acid-base balance in normal physiology, and they don't activate until significant pathology is already occurring. A more complete description of the control of ventilation (including your above point) occurs in the first 5 minutes of another lecture: Respiratory Acidosis (Understanding ABGs - Lecture 11). Thanks for watching!

[@jaquelinemanuel5716]

Thank you doctor Eric for sharing your knowledge to us. You really are a BIG help.

[@ranjanmukherjee2846]

These beautiful and simple lectures on acid base balance were of great help

[@StrongMed]

wai sx, I'm glad you found the video helpful. I've had many requests for specific topics recently, and I'll be trying to get to as many suggestions as possible over the upcoming year. I'll certainly add your great idea to the list, but unfortunately, I can't estimate yet when it might be up.

[@romeolhk1008]

Dr. Eric, you are a genius! Thanks for linking Henderson-Hasselbalch equation with the arrows!

[@sunving]

Thank you Dr Strong ! I know you are busy preparing to face a Covid-19 VA and Stanford. I wish you luck and i am grateful for your effort.

[@StrongMed]

...By adding more CO2 to the blood, the balance between CO2 + H2O and H2CO3 is shifted such that some of that extra CO2 will combine with the H2O to form more H2CO3. H2CO3 levels will increase until a new equilibrium state is reached. Some of the H2CO3 will then dissociate within the blood into H+ and HCO3-, thus increasing the blood's H+ concentration, and lowering its pH.

[@allalover]

Hi dr,, m from Middle East, i v been struggling with the acid bace issue since four dayz however my mind gently started to get the main concepts that helps alot, i do appreciate your effort thank you soo much

[@StrongMed]

Venturer3, in addition to Ryan's explanation, even if you aren't familiar with the concept of Lewis acids and bases (which you don't necessarily need to be), you can understand CO2's classification as an "acid" based on its effect on the concentration of carbonic acid. CO2 and H2O are in constant equilibrium with H2CO3 (carbonic acid) with molecules of H2CO3 continuously breaking down into CO2 and H2O, while other molecules of CO2 and H2O are simlutaneously forming more H2CO3...

[@shuvomd]

Awesome - brings back memories of medical school and has proven invaluable for MRCP (UK) revision. Many thanks!

[@StrongMed]

mrslackalot83: Thanks for the good question! I know that carotid receptors are frequently described as primarily sensors of hypoxemia, but they do also detect changes in pH and pCO2. Their most important role is detecting low pO2 not because it's the most common role they play (actually these receptors don't become active until pO2 < 60mmHg), but rather because there is no other major and reliable mechanism in the body to respond to low O2 with increased ventilation.

[@rizwannazarali7822]

Great lecture Dr. Strong! I am curious to know the classical music segment at the onset.

[@StrongMed]

Was getting over a cold (or as my wife calls it, a "Daycare Associated Viral Syndrome")

[@edipmemisoglu5616]

😂😂

[@MikeBirkhead]

I know I ask too many questions of you, but I have to: - in my lectures and in board-style question banks, I commonly see vignettes in which the pH, PaCO2, and Bicarbonate do not correlate in the Henderson-Hasselbach equation. - this bothers me because it implies that either the vignette is completely fictitious or else that the bicarbonate (calculated) is slightly more complex than I currently understand. - I looked into this and saw that some blood gas analyzers make "corrections" by taking the pH and PCO2 and then re-checking them at a specified pressure or atmospheric CO2 (created with some sort of CO2 cartridge, I presume). - recently a vignette was given (in lecture) with the following values -- pH = 7.25 -- PaCO2 = 65 -- HCO3 = 15 By the equation, pH "should" be extremely alkolotic. Is the patient completely fictitious or is there more to the buffer system than just bicarbonate? - bicarb would have to be about 3 orders of magnitude more potent than any other buffer?

[@lehu8529]

Following helped me greatly with remembering the stimuli for proximal bicarb reabsorption 1) Low pH is obvious :-P 2) Hypokalemia - increasing proximal NaHCO3 reabsorption decreases the sodium availability in the aldosterone-sensitive part of the nephron, thus providing less substrate for the ENaC (i.e., less potassium is secreted) 3) Angiotensin II - it indicates low renal perfusion pressure, which means that there may be increased anaerobic respiration and thus lactic acid production -> so the body increases bicarb reabsorption to sort of prepare for this acid load

[@aldocosta7567]

Your videos are the best time investment ever! Thanks doctor!

[@StrongMed]

Thanks for pointing out the misuse of the term kinetics. Physicians often freely interchange the terms kinetics and thermodynamics when discussing physiology - obviously a bad habit.

[@dcx1287]

Around the 8:00 mark - The equilibrium constant is an empirically derived constant that provides a measure for the thermodynamics - not kinetics - of a chemical reaction.

[@selmayahya6811]

Dear Dr. Eric,I am registered nurse working in PICU. thanks you very much for this lecture. i found it easy to understand and It answer all my question regarding acid base balance. It is useful knowledge as critical care nurse, in deliver a good nursing care . God bless you Dr.

[@ryno1222]

Remember, CO2 is actually a LEWIS acid (in the fact that it collects electrons). There are two types of acids and bases: Lewis and Brownsted-Lowry. CO2 can also be seen as an "acid" in the body since when it increases, H+ concentrations increase, and thus your blood becomes more acidic. Ryan De Leon, RN.

[@cclemonb1222]

"Traumatic memories of high school chemistry" I see what you did there...

[@florianfaehling6458]

Thank you so much for your videos which are in effect the basis of my continous IM resident learning process! I find your explanations by far the best to be found on youtube and also much more detailed than many of the commercial alternatives. I do have one question about the H+/K+ Exchange in acidosis (min 20:41onwards) - what is the clinical consequence of depleted intracellular K+ in severe acidosis? That is, is there a moment when correcting the hyperkalaemia may be dangerous for instance in a patient with severe septic shock and one should instead try to correct the acidosis more aggressively?

[@47thAnuRaG]

For example in DKA, diabetic ketoacidosis with hyperkalemia, don't correct hyperkalemia first. first correct acidosis, potassium may get corrected by itself.

[@eman5669]

@ 16;29 you said hypokalemia stimulates sodium bicarbonate reabsorption at proximal convoluted tubules. I think it is Hyperkalemia?

[@heyitsmedima]

thanks for answering, these lectures helped a lot! hope you have opportunity make more lectures in the future :)

[@waisx4002]

Thankyou very much Dr.Strong =) I'm a medical student, and im only facing problems in Biochemistry because I can't find interest in it, but you've made biochemistry understandable & applicable. May I ask, is it possible to have more videos on biochemistry that is related to the Digestive System?

[@heyitsmedima]

carotid receptors are primarily hypoxemia sensors and central are co2 sensors. why are you using ph/c02 as peripheral stimulus at 15.30sec?

[@lester_ernesto]

Awesome !! Thanks Dr. Strong !! BTW, what's the name is the classical piece you play at the end of each lecture ?

[@p.1127]

first of all, thanks for this great lectures. ı don't understand one point, alkalemia causes hypokalemia via celullar shift mechanism and also hypokalemia causes bicarbonate rebsorbtion in proximal tubule. if these two mechanisms work together, doesn't it cause much more alkalemia?

[@patkap41]

Aren't peripheral chemoreceptors primarily sensitive to O2 concentration?

[@ingrid5400]

Thank you very much Dr Eric!

[@MrShankutube2010]

Thanks Sir for sharing such wonderful informations.

[@wantingtolearn2732]

I have a question if someone could answer it please. If hydrogen protons increase in a cell such as a neuron in the brain or for pain signal, can these protons increase the positive charge within the cell by their increase or binding to negatively charged proteins and thus increase sensitivity? I'm not a medical person, so hope my question makes sense. Thanks.

[@masilafdo3684]

Thank you for sharing your knowledge.

[@kepenetasik]

thank you doctor Eric. this helps me in clearing some key concepts.

[@waisx4002]

Sure it's okay, take your time... I'll hope to see more of your videos soon =D

[@enidginn8986]

I would be really interested in watching a video which explores the pH of blood vs salivary, given that the blood pH is difficult to measure at home, while salivary pH is a simple metric to obtain. Thanks in advance

[@StrongMed]

There's no correlation between the two.

[@sreekanthkomathmohan5277]

Sir it Is An Awesome presentation

[@dcx1287]

Again at 12:45 - "As CO2 is eliminated from the body formation of new CO2 from the ion pair via carbonic anhydrase becomes kinetically favorable" - this should read becomes "thermodynamically favorable" as opposed to "kinetically" favorable. Really the elimination of CO2 leads to a local disequilibrium between the H+, HCO3- pair, carbonic acid, and CO2 and therefore results in a left shift of the entire equation, thereby favoring (initially, at disequilibrium conditions) H+ elimination.

[@bxxxl9447]

I wish I had heard you years earlier, sir

[@elfllal]

really brilliant you illustrate everything by very simple method & very nice illustrations thanks a lot :)

[@TroyeStonich]

My wife loves these!

[@haleylee4173]

It is very clear. Thank you so much

[@dcx1287]

And of course by "H+ elimination" I simply mean H+ combination with HCO3- to produce the undissociated H2CO3.

[@DagaYute]

Thanks doc this is really awesome!

[@khateebyassin]

Very useful !!! Thanks deeply

[@dcx1287]

One last caveat just for the sake of thoroughness - of course when I say "equilibrium" conditions within a biological context I really mean "steady state."

[@janelast5177]

You are a genius Thanks

[@MrTenacity99]

Brilliant. Thanks.

[@ashakrishna8934]

Thank you Dr Eric i am using your lectures for USMLE step 3

[@291ayl]

pKa has nothing to do with rate, it has to do with theromdynamics.

[@rambhoopalreddy3802]

thank u sir

[@xsq12]

many thnx

[@venkybly]

Tq

[@w.t.6668]

la terminale euro de mr mORIN on est la

[@spainvillanumberone]

i get it now

[@Soubhi.Tenawi]

2023 anyone?

[@mohammedmukthar7791]

2024

[@sujathasistla4622]

Not very interesting way of presentation and not easy to follow

[@StrongMed]

Ouch! Please keep in mind that this video is 10 years old, and was one of the first posted here. I think you'll find my newer stuff a significant improvement. (Though I haven't yet remade this particular topic)