5. Essentials of Renal Physiology Pt. III Flashcards
K in Body Fluids
- Normal serum [K] is ____ to 5 meq/L
- Extracellular K is not bound and is freely ____.
- Normal intracellular [K is ____ to 150 meq/L• ____ orders of magnitude difference
3.5
filterable
120
2
The Nernst Equation Cares
- Cell membranes from excitable tissues are more permeable to ____ than Na or Cl.
- Therefore, the resting membrane potential Em is given by the Nernst’ equation:
Em =-RTln[K]i =-61.5log[K]i =-80to-90mV F [K]e [K]e
3. Since [K]i is relatively constant, small changes in [K]e will have large changes in \_\_\_\_ and dramatic consequences in \_\_\_\_ rhythm and neuromuscular function. • K is the major determinant of resting potential of cells • Cause EC gradient > chemoelectrical gradient ○ \_\_\_\_ gradient is first thing that happens § Differing cxn of K+ on side to another ○ The positive charges from K+ very rapidly builds up + charge on one side that pushes back \_\_\_\_ on the concenrtration gradient ○ Electrical charge exits on diff scale of cxn vs normal cxn that we talked about • K+ is the only one where there is a permeability in the d\_\_\_\_ state ○ Other oions have huge cxn gradient (Na+, Cl-), don't have permebalityt in the resitng state ○ Determines the resting state of excitable cells § Low K outside the cell > make the few K+ go down concentration gradient, and make a molar polarized cell □ Hypokalemia ® \_\_\_\_ the cell ® Opposite happens with hyperkalemia (less K+ crosses, cell is more \_\_\_\_) □ Either abnormalities > lethal on the heart ® Cardiac arrhythmia ◊ Low K+ state > hyperpolarized > makes volt-channels more \_\_\_\_ > increases the risk for lethal tachyarrhythmia
K
Em
cardiac
conc equally resting hyperpolarize depolarized excitable
• Depolarize past threshold > voltage-gated channels open > create ____ to other ions (Na+, Ca++) > further depolarizes the cell > channels have a time-limit and then close > permeability goes away > open up voltage K+ channels > return the cell back to it’s resting potential > ____
perms
overshoot
Potassium
• Input – \_\_\_\_ (oranges, bananas, potatoes, tomatoes) • Output – \_\_\_\_, Renal • Shift (Can have a BIG impact)
* Kidney is regulated; \_\_\_\_ is not * Shift of K+ in or out of cells will have a large impact on extracellular K+ cxn
food
GI
gut
• In and out is the ____ amount
○ Any shift in the ECF, and the ICF > ____ deal
same
big
Major Site Of Regulation of Potassium Excretion:
• The ____
cortical collecting tubule
Cortical collecting duct: principal cells
• Enac > allows Na+ to go in by itself > net \_\_\_\_ charge in lumen ○ Inhiibted by \_\_\_\_ • K+ channel > allows K+ to go out > pulled out by net \_\_\_\_ charge • Whole system stimualted by \_\_\_\_
-
amiliodarione
-
aldosterone
Potassium - Output
• To adequately excrete potassium via the kidneys you need 3 components:
- ____ (ie, enough nephrons working)
- ____ at the cortical collecting tubule
- ____
Absence of any of the above can lead to ____• GFR
○ Nephrons working
• Urine flow with Na+ in it at the CCT
○ Cannot have resorbeda lot before urine got ot the CCT
• CCT swithced on by aldosterone
• Can lead to hyperkalemia in the setting of ____ K+, or cells ____ DOWN THINGS
GFR
urine flow
aldosterone
hyperkalemia
ingesting
breaking
Elevation of both #2 and #3 can lead to K ____
• Elevate both the urine flow and ALD > wasting K+ at the site of the CCT ○ These two things never go in same direction § High \_\_\_\_ diet > flow of urine and amount of Na+ will increase □ ALD will be \_\_\_\_ □ These two are working in \_\_\_\_ directions § Salt restricted diet □ Volume \_\_\_\_ □ ALD will be \_\_\_\_ □ Proximal resoprtion of Na+ will be high > urine flow at last segment of nephron will be \_\_\_\_
wasting salt low opposite deplete high low
• High ALD and high urine
○ Diuretics
§ If block Na+ resorption ____ to distal nephrone/collecting duct > K+ ____
□ Hypokalemia
® Not everyone gets it because they ____ so much K+ > they keep up with their losses
• [???]
proximal
wasting
eat
Potassium Shift
Shift INTO cells • \_\_\_\_ • Beta-agonists (like albuterol) • \_\_\_\_ • Hypo-osmolarity (acute)
Shift OUT OF cells
• ____ due to fasting (generally mild effect)
• Hyperchloremic Metoabolic Acidosis
• ____ (acute)
• Cell rupture (rhabdomyolysis, hemolysis)
• Insulin is most clinically important; big part of treatment for \_\_\_\_ ○ Shifts K+ into cells • Cell rupture ○ Breaking down ○ Hematoma being reaborbed
insulin
hypo-osmolarity
insulinopenia
hyperosmolarity
hyperkalemia
• Changes in EKG as hyperkalemic
○ Peaked ____ wave
• Can cause letahl ____ and can stop heart
○ Hyperkalemia puts volt gated cells in state where cannot ____
• Open heart surgery > stop heart > the way they stop is via big dose of K+ IV
• Lethal injections > K+
T
arrythmia
open
Treatment of Hyperkalemia
Step 1: Stabilize cardiac cell membranes
-____ or calcium chloride
Step 2: SHIFT potassium back into cells
-____ (usually given with D50 to prevent hypoglycemia)
-Albuterol
-____
Step 3: Get it OUT
-____ (if kidneys working) -Sodium polystyrene sulfate (kayexalate) -____ (f kidneys not working)
• Stabilize the cell membranes ○ Having high EC \_\_\_\_++ decreases impact of hyperkalemia • Most impotant acute therapy is INSULIN ○ Rapidly casues K+ to go into cell, and if normal blood sugar and give \_\_\_\_ § Want to avoid acute hypoglycemia • Step 1/2 are temporizing manuevers > will give time, but will not remove K+ from the body • Diuretics can act proximilaly in nephrone > K+ wasting ○ In patients who are not volume deplete > give a \_\_\_\_ ○ If hypovolumeic > give \_\_\_\_, and then add a loop diuretic in ○ K+ binders > SPS > bind K+ in the \_\_\_\_ § Resin that binds K+ ○ If kidneys aren't working > dilaysis
calcium gluconate
insulin
sodium bicarbonate
fursosemide
dialysis
Ca
loop
saline
gut
Treatment of Hypokalemia
• Give ____
• (but don’t give too much too ____) • ‘Nuff said
* Give K+ too fast > cardioplegic > deadly * Slow > challenge to those who are losing a lot of K+ due to diarrhea
potassium
fast
Why Do We Care?
• [H+] is very ____ regulated
• H+ ions are small; they associate closely with proteins and alter their function
• [H+] is regulated on a ____ scale – Normal is 40nM (pH 7.4)
– Range compatible with life is ____ nM
(pH 7.8- 6.8)
• Small > allows to get close ot proteins and affect function ○ Proteins feel presence of protons acutely • Up until now, everything has been on the mM scale (1000th), and now we're on nM (billionth) ○ Huge difference in cxn • Narrow range compatible with life because in nM!
tightly
nanomolar
15-150
pH: A Stupid Unit Invented to Deal With All the Zero’s
• pH = -log[H+] • Acid: substance that increases [H+] – Lowers pH • Base: substance that decreases [H+] – Increases pH
• The unit is not \_\_\_\_; going from .1 change is different ○ Going from 7.0 to 7.1 > different change than from 7.1 to 7.2 because it's a log scale
proportional
- Most acid > ____ (2.0)
* Anything below ____ > lowest a human can survive; and once above ____ inconsistent with life
stomach contents
- 6
- 8
Challenge For The Body
• [H+] is on nanomolar scale
• Normal diet and metabolism adds ____ of H+ to the body
– 1 millimole = 1 million nanomoles
millimoles
cahllenge for the body
• Nm scale of ph, add/sbstatct acid on mM scale ○ Diet is 10 mM of acid per day > need to have kidney excrete 70 mM of H+ per day to stay in steady state ○ Kreb cycle generating CO2 > make 15,000 mM per day § Every CO2 is a potential acid ○ A lot of acid generated in something that must be \_\_\_\_ and fixed
low
HA H++A-
• Buffers require a ____ (HA) and a ____ (A- )
• Acid and base loads are handled by changing between these two forms to prevent large changes in free [H+]
* Add acid to system > excess anion > can bind the acid and drive equil to the left > no free proton that can assoc to protein * If opposite > lose proton > equil to right > donate a proton to the system
hydrogen donor
hydrogen acceptor
Characteristics of an Ideal Buffer
- In sufficient quantity, that it can “absorb” the acid-base load and keep the pH ____ over a wide range of potential insults
- The ____ (base) and donating pair in the buffer are in approximately equal quantity
- The ____ of your acid base pair should be near your ideal pH• Add acid, pH is dropped a lttle, but most is bound by buffer until you run out and then you drop very quickly
stable
acceptor
pKa
BODY BUFFERS
• ECF buffers – \_\_\_\_/carbonic acid/CO2 • H+ + HCO3– H2CO3 CO2 + H2O – Plasma proteins – Inorganic \_\_\_\_
• ICF buffers
– ____ (red blood cells)
– Proteins
– Inorganic____
• ____ (potentially very large buffer reservoir)
– Releases NaHCO3, KHCO3, CaCO3, CaHPO4 in response to acid load
– Accounts for up to ____% of acute acid/base buffering
• CO2 is in equil with bicarb and a. Proton • Buffers inside cells • Bone is a large buffer ○ HA in bone does a lot of buffering • Only know about bicarb buffer system ○ The others are dificult to measure
bicarbonate phosphate hemoglobi phosphate bone 40
• ____ very unstable > impossible to find because changes between the two states
○ Often left out when describing the equilibrium
• Carbonic anhydrase
○ ____ (PCT) and cytosoloic forms
• The bicarb is present on chem 7
○ Measure every single day ebcasue its importantt acid base balalnce
H2CO2
luminal
• \_\_\_\_ is how the CO2 is measured ○ Not same as \_\_\_\_ CO2 ○ Must multiply by factor to get dissolved • Normal pH of 7.4 • Do not memorize equation/do math
pCO2
dissolved
HCO3–/H2CO3 Buffer System
Why is it so important?
- One component (____) is tightly regulated by the kidneys
- The other component (CO2) is independently regulated by the ____ (i.e., it is an “open” buffer system—the solution containing the buffer equilibrates with the environment)
- ____ measured
- Most ____ extracellular buffer• Has features that aren’t present in other buffer systems
• Impact by two organ systems
○ Two safety valves
• Bicarb
○ Regualted by the kidneys (resorbing, and also generate)
• CO2
○ Regualted by the lungs
§ Rate in which breathe > determiend by the need to get rid of CO2
• Creates an open buffer system > in equil with the outside world > makes buffer more ____
• Easily measure because can measure stuff in blood
HCO3- lung easily abundant powerful
• A liter of fluid that has a PCO2 40mmHg (normal); HCO3 24 (normal); and a normal pH
• If removed the buffers (no bicarb)
○ The pH would be ____
2
• Add buffer and close system > and no movement of fluid
○ Add acid > will be buffered by bicarb > goes down to 14
§ The protons are sucked up by bicarb > equil to th e ____
§ Closed > CO2 staying insdi eteh box > push equil back to the ____
□ The pH will be ____
□ Still below what is seen in the rang ecompatbaile with life
• Turn into an open system
○ Fix the concentration at 40 (CO2)
§ Will be sept by gas (same as breathing)
§ CO2 ____ pushing equil to the right; a BETTER job buffering
□ pH will be ____
§ Bicarb is the same > ever so slightly different
□ The same as difference in + cxn
□ Will be slightly lower in the open system because going to the ____
left right 6.2 not 7.2 left
This is how we get rid of all the CO2 generated by the krebs cycle
• Retain CO2 > quickly the pCO2 will lead to generation of acid and bicarb > protons affect proteins > in trouble ○ Will survive a monthish • pCO2 in air is close to 0, mix ore outside air with gas generated in alvoeli > bring mor eamibent air > lower the \_\_\_\_ in the avlolaer gas > the pCO2 is determiend by the \_\_\_\_ > breath faster > allow lungs ot ompentsat eofr \_\_\_\_ being added to the body ○ Compensation will make pH be better ○ Lower pCO2 further > can bring the pH up to \_\_\_\_ ○ Bicarb did NOT increase; it actually would've \_\_\_\_ as a result of compensation • Lungs set the \_\_\_\_; kidneys restore the \_\_\_\_
pCO2 ventilation acid 7.3 decreased CO2 bicarb
This is how we get rid of all the CO2 generated by the krebs cycle
• Retain CO2 > quickly the pCO2 will lead to generation of acid and bicarb > protons affect proteins > in trouble ○ Will survive a monthish • pCO2 in air is close to 0, mix ore outside air with gas generated in alvoeli > bring mor eamibent air > lower the \_\_\_\_ in the avlolaer gas > the pCO2 is determiend by the \_\_\_\_ > breath faster > allow lungs ot ompentsat eofr \_\_\_\_ being added to the body ○ Compensation will make pH be better ○ Lower pCO2 further > can bring the pH up to \_\_\_\_ ○ Bicarb did NOT increase; it actually would've \_\_\_\_ as a result of compensation • Lungs set the \_\_\_\_; kidneys restore the \_\_\_\_
pCO2 ventilation acid 7.3 decreased CO2 bicarb
“Compensation”: does not restore the ____
Lungs: set the ____
Kidneys: restore the ____
bicarbonate
pCO2
bicarbonate
Henderson-hasselbach
• pH is determiend by ____ over ____
kidney
lung
Henderson-Hasselbalch Applied
• Bottom Line
– Rise in HCO3- causes a rise in ____
– Drop in HCO3- causes a drop in ____
– Rise in CO2 causes a decrease in ____
– Drop in CO2 causes a rise in ____
* Inc bicarb and no other change > pH rise > more alkaline > fewer protons * Drop bicarb and no change > drop pH > more protons
pH
pH
pH
pH
Respiratory Mechanisms
• Exhaling ____ is an excellent way to rid the body of acid, specifically volatile acids
(Recall: CO2 + H20 ↔ H2CO3 ↔ H+ + HCO3-)
• Alveolar ventilation can be ____ rapidly
• The pH of the body influences the rate of alveolar ventilation
– ↓ pH triggers increased ____, more CO2 is lost, [H+] decreases and pH ____
– ↑pH triggers decreased ventilation, ____ accumulate, [H+] increases and pH ____
• Acid > stimulate more ventilation > breathe faster > pH goes up • Alkaline > inhibit breathing > drive pH back down • Overdose of opiates > high doses > inhibits ability to detect acidemia > stop breathing > hypercarbic and hypoxic ○ Antidote: narcan > rapid rescue bc causes them to breathe
carbon dioxide titrated ventilation rises CO2 falls
How to Increase Ventilation
1. Increase ____ of Breathing 2. Increase ____ of Breathing
• Both = Kussmaul breathing= seen in severe ____
rate
depth
acidoses
Kidney Has Two Jobs Regarding HCO3– Balance
- Prevent ____ of filtered HCO3-
- “Create” new ____
- Protons that have sulfates and + charge > metabolized > generate acid > destroys ____
- Segment of nephron resorbs filtered bicarb > ____
loss
HCO3
bicarb
proximal
Prevention of HCO3– Loss
- HUGE amount of HCO3– filtered daily
- Almost all is resorbed in the ____
proximal tubule
Promixal tubule ' • Na/H exhcnager • Na in and proton goes out • Proton with bicarb • Luminal CA • \_\_\_\_ into cell > spltis into + and bicarb • \_\_\_\_into urine • \_\_\_\_ leaves the cell
CO2
proton
bicarb
HCO3– Resorption Rest of the Nephron: Weak Sauce
- If HCO3– resorption in proximal tubule is disrupted, then the rest of the nephron cannot “____”
- Onc ebicarb is past PCT > poorly abosbre danion > difficulty getting out of ____
catch up
urine
Carbonic Anhydrase Inhibitors: Lower Serum [HCO3–]
* Inhibit the CA then you can cause biarb wasting > will be in \_\_\_\_ and exit body bc the nprhon cannot catch up witht elack of bicarb absorption in th eproximal tubule * CA inhibitor is the only diuretic that would have taken > going into high altitude to compensate for low pCO2
urine
“Creating” New HCO3–
- Kidney needs to pump ____ into the urine
- Where does this happen?
- ____
- Here come another couple of slides from the sodium lecture• Make the urine acidic
○ CCT - site of interaction with Na, K and acid base physology
H+
cortical collecting tubule
Remember Question:
• What if you wanted to reabsorb Na+, but the anion it was paired with was not resorbable?
• You would have a ____
cation exchanger
Principal Cells Help Process by Making Lumen Negative, But Do NOT Have H+ Pumps
• Prinicipal cells ○ Make the lumen negative by allowing Na+ to traveld own cxn grdaient and allow K+ to leave but don’t have channels that facilitate \_\_\_\_ to leave ○ Most comonly found cell in renal tubule/epithleium • Intercalated cells ○ Separate ○ Differne tmorphologies > will focus on \_\_\_\_ (ecerteting acid) § Can change in alkemia ○ Alpha § Two pumps § Every other channels is a passive channgel; this is th eone palce where there's another pump that burns \_\_\_\_ itself □ Up the cxn gradient § \_\_\_\_ ATPase § \_\_\_\_ ATPase § Most quanitfyabtlae important.> \_\_\_\_ ATPase □ Majority of pumping □ CO2 inside cell >sppit into proton and bicarb > take H+ and pump inot \_\_\_\_ > leave a bicarb that stays in obdy ® Good enough?
H+ alpha ATP H+ H/K H+ lumen
Alpha-Intercalated Cells Establish H+ Gradient
• The ____is the major proton pump for these cells
– H+/K+ ATPase has minimal role
• Able to establish pH of ____ in the urine even though pH is 7.4 in the blood
• But:
– pH of 4.4 is only 0.04mMol [H+] per liter
– Kidney typically has to get rid of 70 mMol/day! – How does kidney do this?
• One liter of urine is getting rid of 0.04 mmol ○ Need to get rid of 70 mmol per day > would have to make 100's of liters of urine in order to get rid of enough protons ○ What else? § BUFFER! □ Buffer in urine □ \_\_\_\_ (excess in food) □ Only one regulated: ® \_\_\_\_ (NH4+)
H+ ATPase
4.4
phosphate
ammonium
Buffers
• Many of the substances the kidney excretes are also buffers
– ____ is a major one
• Only one is these buffers is regulated: – ____(NH4+)
phosphate
ammonium
Proximal Tubule Makes NH3 from Glutamine to Buffer H+
• Prox tubule cell > \_\_\_\_ ATPase • Cell also takes AA (\_\_\_\_) > generates \_\_\_\_ > goes into urine ○ If no acid urine in distal tubule > ammonium reasborbed > \_\_\_\_ > undo work of proximal tubule in generating it ○ MAKE AMMONIA IN PROX, BUT TRAP IN THE \_\_\_\_ § Pumping + into with ATPase, suck up proton with ammonia > ammonium > no longer pushign on cxn gradient on the pump that's tryig to ush more protons out
Na/H glutamine ammonia metabolized CCT
Handling of NH3 and NH4+ in the Tubule is Complicated
- NH4+ can be reabsorbed in the tubule and then later ____
- If pH is not acid in the distal tubule, then NH4+ will be reabsorbed and “undo” the work of the ____
- Take-Home message is that the distal tubule “traps” in the tubule by secreting ____
secreted
proximal tuule
proton
Three Things Needed for Kidney To Excrete Acid Generated by Metabolism 1. Reclaim all filtered \_\_\_\_ 2. Make urine pH \_\_\_\_ 3. Create sufficient \_\_\_\_ (ammonium)
• Missing one of three things > will not be in completley \_\_\_\_status
bicarbonate
low
buffer
normal acid-base
Four Step Process
- What’s the “____”?
- What’s the “____”?
- Is there appropriate ____? 4. Is there a widened ____?
emia
osis
compensation
anion gap
Definitions: “emia”
• “-emia” refers to the actual ECF ____
– “Normalemia”: ____pH (7.38–7.42)
– Acidemia: ____ pH (<7.38) – Alkalemia: ____ pH (>7.42)
• Determined by pH from ____
• A patient can have only ____ “emia” at a time
• Blood gas - tells about CO2 and O2 in blood at th esame time • Emia is where you are in acid-base land > one place at particualr time ○ As opposed ot an osis which is a process
pH normal low high blood gas one
What The Heck Is An “Osis”?
• An “osis” are process that changes ____
pH
Processes that change pH
- Acidosis: ____ [H+]
- Alkalosis: takes ____ [H+]• May have started middle > acidosis > two steps to the right > acidemia
○ Can also have severe osis, but also an alkalosis > and can end up in the same psot
adds
away
• Acidosis: \_\_\_\_ [H+] • Alkalosis: takes \_\_\_\_ [H+] • Respiratory “osis > changes \_\_\_\_ • Metabolic “osis” > changes \_\_\_\_ • Each “osis” has its appropriate \_\_\_\_ – Metabolic “osis”> \_\_\_\_ – Respiratory “osis” > \_\_\_\_
adds away pCO2 [HCO3-] compensation respiratory compensation metabolic compensation
“Osis” versus “Emia”
• “…osis” is a ____
– Acidosis: respiratory, metabolic
– Alkalosis: respiratory, metabolic
– Can have ____ than one at a time (maximum ____) – Does not tell us the ____ of the blood
• “…emia” indicates the change in blood ____ – Acidemia: pH < 7.35
– Alkalemia: pH > 7.45
– Does not tell us ____ we got there
– Can only be ____ pH at a time!
• If acidemic, you know at a minimum that you have an acidosis ○ But do not know what kind, how many, etc. ○ And same applies for alkalemic
process
more
3
pH
pH
how
one
Respiratory Alkalosis
• pCO2 less than ____ mm Hg (____)
• Most ____ acid- base imbalance
• Primary cause is ____
• Things that make you breathe fast ○ Causes RA • Not clinically detected/significant ○ Do not check a \_\_\_\_ for these people if something else wrogn isn't present
40 hypocapnea common hyperventilation blood gas
Respiratory Acidosis
• ____ levels of CO2
– CO2>____mmHg.
• Hypercapnia – high levels of ____ in blood
• Typically due to airway compromise resulting in ____ – classic is ____.
* Acute and sudden * Can be lethal in the face of taking heroin/fentynl IV
elevated 40 CO2 hypoventilation COPD
Metabolic Acidosis
• Increased [H+] because of drop in ____
[HCO3-]
Why Metabolic Acidosis Occurs
Usually one of three processes:
1. ____ of acids (acids produced faster than they can be excreted)
§ Abnormal metabolism: ____, ketoacidosis
§ Substances that cause acid generation: ____,
methanol, ethylene glycol
2. Loss of ____ (bicarb) directly
§ GI: ____ (most common)
§ Renal: Proximal Renal Tubular Acidosis (RTA)
3. Lack of ____ of new base
§ Low ____ excretion (____ RTA)
* Lactic acidosis > no \_\_\_\_ of vital organs * Ketoacidosis > insufficient \_\_\_\_ to undergo normal metabolism * Sialyclic acid (aspirin) > works by inhibitng normal metbaolism > alctone/ketone generation * Abnormal alcohols > mebtaolized to formate/ox acid * Low ammonium can be due to not making enough, or not having th e\_\_\_\_ that pushes it up the cxn gradient
overproduction lactic acidosis salicylates base diarrhea synthesis ammonium
perfusion
insulin
pump
Overproduction of Acids
• They All “Leave Behind” a ____:
HA > H+ +A-
conjugate anion
The “Anion Gap”
[Na] + [Unmeasured Cation] = [Bicarb]+ [Cl] + [Unmeasured Anion]
[Na] - [Bicarb]- [Cl] = [Unmeasured Anion] – [Unmeasured Cation]
[____] - [____]- [____] = Anion gap
Usually this gap is a set amount of unmeasured anions (we assume unmeasured cations are negligible)
When the gap increases above 10, this suggests the addition of an ____ in an amount noted equivalent to the increase in the gap
• Differenc ebt measrued cations and anions • Not a lot of measured cations other than Na+ • Antions ar eclhoride and bicarb • Anions are usaully slight in difference ○ Anion gap = \_\_\_\_ anions ○ There are anions there, but they're not measured anions • NEEDED (not noted) • Anion gap widened (> 10 meq/L) ○ Calling card of an acid that's been added to the body
Na bicarb Cl acid unmeasured
Most Important Causes of Gap Acidosis
- ____
- Ketoacidosis
- ____
- Toxic alcohols
lactic acidosis
salicylate
Metabolic Alkalosis
• Bicarbonate ____ - concentration in blood is greater than 24 mEq/L
• Causes: – Excess \_\_\_\_ = loss of stomach acid – Endocrine disorders – particularly \_\_\_\_ – Heavy ingestion of \_\_\_\_ – Severe \_\_\_\_
• Remove HCl > leaving behind bicarb ○ Acid generated by splitting CO2 and H+ ○ The H+ comes back in, or the bicarb will be secreted into the GI • CCT secreting protons; if CCT is upregualted by aldo, then more + into the urine, and will leave \_\_\_\_ behind • Antacids have bicarbs in them • Severe volume depletion via NaCl
excess vomiting hyperaldosteronism antacids volume depletion bicarb
Compensation
• If underlying problem is metabolic >
– Bicarbonate < 24 = ____ (nml bicarb ~24)
– Bicarbonate > 24 = ____
– Respiratory compensation by either increasing or decreasing ventilation and as a result, altering ____
• If problem is respiratory >
– CO2 < 40 = ____ (nml CO2 ~ 40)
– CO2 >40 = ____
– Increased ventilation, increases CO2 ____ and reduces the CO2
– metabolic compensation by either increasing or decreasing ____ excretion
• Compensation never fully ____ the underlying abnormality
acidosis alkalosis CO2 alkalosis acidosis excretion acid corrects
Compensation for Metabolic Acidosis
• Increased ventilation
– The expected respiratory compensation is given by the formula (aka ____ formula):
– Expected pCO2 (on ABG) = 1.5 ([HCO3]) + 8 2
– Winter’s formula only works for ____
• There are other compensation equations, but they are beyond the focus of today’s talk
* Gives the expected \_\_\_\_ compensation * Each acid-base disorder has it's own compensation equation
Winter’s
respiratory alkalosis
respiratory
ACID-BASE DISTURBANCES SUMMARIZED
Resp acidosis
Primary disturbance: ____ CO2
Compensation: ____ HCO3-
Resp alkalosis
Primary disturbance: ____ CO2
Compensation: ____ HCO3-
Metabolic acidosis
Primary disturbance: ____ HCO3-
Compensation: ____ CO2
Metabolic alkalosis
Primary disturbance: ____ HCO3-
Compensation: ____ CO2
inc
inc
dec
dec
dec
dec
inc
inc
Strategy for Analyzing Acid-Base
Problems
How to identify the primary disorder
1. Look at ____
• Acidemia
• Alkalemia
- Look at pCO2 (acid)
• High pCO2 ® ____
• Low pCO2 ® ____ - Look at HCO3- (base)
• High HCO3- ® ____
• Low HCO3- ® ____ - Look for ____
pH
respiratoyr acidosis
respiratory alkalosis
metabolic alkalosis
metabolic acidosis
compensation
Strategy for Analyzing Acid-Base problems
• Always calculate the ____
• To identify a mixed acid-base disorder, assess whether compensation is appropriate:
– If a metabolic acidosis is present, calculate the expected pCO2 using ____
Arterial blood gas:
____ / pCO2 / ____
anion gap
winter’s formula
LOOK AT THE QUESTIONS!
ya
