Acid-base homeostasisWhich substance is a stronger acid; H2SO4 (pKa -4) or HCl (pKa -3)? Flashcards

: H2SO4 because the pKa is lower, it will more readily donate a hydrogen...even though pure versions of both substances will readily burn your skin off

1. Dissolved in the plasma
2. Carried in the RBC
a. Bound to hemoglobin (carboxyhemoglobin)
b. Dissolved inside erythrocytes
3. Dissolved bicarbonate (HCO3) in the plasma transforms into carbonic acid (H2CO3)

She will breathe it out because her carbonic anhydrase will combine the excess hydrogens with bicarbonate to create carbon dioxide to be breathed out. Unfortunately, Aspirin overdose will also have other undesirable side effects.

● Increased CO2
● Acidosis
● Increased DPG
● Exercise
● Increased Temperature

note: “CADET, face Right!”

Answer: CO2, Acidosis, Exercise, and Increased temperature

Answer: 3.5 mg/dL - the reference range for serum potassium is 3.5-5.0 mg/dL

note: This means that much of the intracellular potassium will be excreted in the urine

The correct answer is C. The Henderson-Hasselbalch equation is used to figure this out.
pH = pKa + log (Base/Acid)
pH = 6.35 + log (20/1)
pH = 6.35 + 1.30
pH = 7.65

This pH is close to the homeostatic physiologic state. While the carbonic acid buffer is one of the most prevalent in our bodies, it is by no means the only buffer system in our body. The rest of the acidity comes from the proteins and other factors to bring the pH closer to 7.4.

The correct answer is B. Increased 2,3-DPG concentration leads to a “right-shift”, therefore if it’s lacking, then we have a “left shift” of the curve. This leads to oxygen retention on hemoglobin and allows for more hemoglobin to be saturated at a specific partial pressure of Oxygen.
Remember the mnemonic “CADET face right!

The correct answer is A. Remember the enzyme carbonic anhydrase and how it can interconvert CO2 , H2O, H2CO3, H+, and HCO3. Each one of those molecules can transform into another quite rapidly. Metabolic acidosis is an excess of H+ in the body. The HCO3- will bind to the H+ to form H2CO3 , which will then be turned into carbon dioxide and water to be excreted.

The correct answer is A. We would expect her chloride level to be elevated. This young girl is breathing rapidly which efficiently removes CO2 from the lungs. With such rapid breathing, you
can blow off so much CO2 that you become alkalemic. This is called respiratory alkalosis and occurs with hyperventilation. The treatment for hyperventilation is to breathe into a bag. You breathe back in the same CO2 that you breathed out, so it helps you not become so alkalotic. Because this girl is already alkalotic, the bicarbonate (HCO3-) in her blood will be exchanged for Cl -in the RBCs. This will cause an increase in the extracellular Chloride concentration
(hyperchloremia)

Answer:
Clarke Electrode, which is amperometric and measures the current produced after being exposed to a standardized potential between two electrodes.

pH: 7.35-7.45

pCO₂: 34-45 mm/Hg

pO₂: 90-100 mm/Hg

HCO₃: 22-28 mEq/L

HCO3 - is calculated from the Henderson-Hasselbalch equation using pCO2 as the acid species, a pKa of 6.4 for H2CO3, and the pH. I don’t think that you’ll be required to calculate it, but you will NEED to know that HCO3 - is CALCULATED and NOT directly measured.

pCO2 is decreased in hyperventilation. With more breaths per minute, more CO2 is removed from the blood. pCO2 is increased in many other pulmonary disorders which impair gas exchange in the pulmonary capillaries (e.g. emphysema, atelectasis [collapsed alveoli], pneumonia, Acute Respiratory Distress Syndrome
[ARDS], pulmonary edema, etc.).

With an alkalotic pH, either pCO2 is decreased or HCO3 is increased. Usually, whichever one deviates in the direction that would cause the pH change is the primary cause

respiratory alkalosis because the person is breathing so quickly and has adequate gas exchange, so they are breathing off all of their CO2

1. High pH
2. Low pCO2
3. Variable HCO3- (due to compensation and chronicity)
4. Is the pH in the 7.35-7.45 window?

respiratory acidosis because of the inefficient gas exchange inside the lungs. These patients may be short of breath and breathing quickly, but they can’t get rid of their CO2.

1. Low pH
2. High pCO2
3. Variable HCO3- (due to compensation and chronicity)
4. Is the pH in the 7.35-7.45 window?

= metabolic alkalosis because they all create a basic environment for the body. In hyperaldosteronism, the kidney is forced to retain
Na+ at the expense of K+ , but still tries desperately to regulate the K+ concentration in the body. It is able to reabsorb a fraction of the K+ , but it costs one H +, causing alkalosis.

1. High pH
2. High HCO3 -
3. Usually High pCO2
4. Is the pH in the 7.35-7.45 window?

= metabolic acidosis because each pathology creates an acid that cannot be removed as quickly by the kidneys … so it hangs around for a while.

1. Low pH
2. Low HCO3-
3. Usually Low pCO2
4. Is the pH in the 7.35-7.45 window?

Answer:
We would expect to see a primary metabolic alkalosis with a secondary respiratory acidosis. The mechanism revolves around the function of aldosterone which retains Na + in exchange for K+ causing hypokalemia. The peritubular capillaries have a H+/K+ exchange pump which goes at full force to retain as much K+ as possible, but does so at the cost of a H +. The body is now starving for both H + and K+ !

1. Blood gases must ALWAYS be collected on ice in a fluoride tube and be assessed within 30 minutes, leukocytes continue to metabolize oxygen after the sample is taken, so rapid assessment is ALWAYS best

2. Electrodes don’t allow for diffusion very easily when there is protein build-up on the membranes, nor do they function outside of the standard temperature or barometric pressure that they are supposed to operate under. However, improper calibration is one of the most
common sources of error.

3. Probably one of the most common sources of error for the Clarke electrode is improper collection. If the sample can be exposed to room air during collection, transportation, or measurement; be deliberate and cautious with how you handle blood gas samples.

Blood gases need to be collected in a fluoride tube (gray top), transported on ice, and assessed within 30 minutes.

The correct answer is B. Respiratory Acidosis occurs because even though the patient is likely breathing quickly, he is unable to efficiently transfer oxygen and carbon dioxide into/out of his blood because of his pulmonary disease (emphysema). So, if you were
thinking hyperventilation would cause respiratory alkalosis, that is a great thought, but each time he breathes, it doesn’t contain much expired CO2 because of the inefficient gas exchange in his lungs. Here are values that I would expect in a patient such as this:

The correct answer is D. Our patient should have a fully compensated process because she’s been living with it for 5 years. The tumor is likely hypersecreting aldosterone which will cause the kidneys to retain Na+ at the expense of K+. One of the main reasons why
this has an effect on Acid-Base homeostasis is because of a K+/H+ channel in the distal convoluted tubule of the nephron. Since our body is short on K + , it’s going to get as much as it can through this channel. We reclaim a K+, but give up a H+, leaving us in an
alkalotic state. Here is a panel that I would expect from such a patient:

The correct answer is D. This woman is hyperventilating which will cause her to breathe off her CO2. This will decrease her pCO2 and thereby, decrease the H + that is produced from carbonic anhydrase. The circulating HCO3- goes unchecked and causes an alkalotic state. Because HCO3 - cannot be excreted immediately by the kidney, the
expected compensatory pattern of metabolic acidosis would not be seen acutely and would likely take a day or two to develop. Here is a panel that I would expect from such a patient:

is any concentration of Hydrogen atoms above the baseline and has a pH lower than 7.35, we see this in vivo as increased pCO2 or decreased HCO3

is any concentration of Hydrogen atoms below the baseline and has a pH higher than 7.45, we see this in vivo as decreased pCO2 or increased HCO3

Hypoxia is the general term that means we are breathing in less oxygen than we need

Hypoxemia means that we have low levels of oxygen in our blood

the ratio of Bicarbonate to Carbonic Acid in the body is 20:1

Bicarbonate Buffer System - H2CO3 and HCO3-

by the kidneys through metabolic compensation, and usually a Ph change occurs after a few days

by the lungs through respiratory compensation, and can occur immediately

1.NH3 production and NH4+ secretion in the urine

2.Na-H exchange pumps

3.Conservation of Filtered H2CO3

The tubular lumen is more acidic than the blood

NH3 binds to H+ in the urine filtrate creating NH4+

NH3 can diffuse through plasma membranes, but NH4+ is trapped

1. CO2 carried in RBC

2. HCO3- dissolved in plasma as carbonic acid

3. CO2 dissolved in plasma.

Breathe more to reduce the acid to Decrease levels of pCO2 and Increase the levels of HCO3

Breathe slower to compensate to Increase the levels of pCO2 and Decrease the levels of HCO3

is when the pH is outside the 7.35-7.45 window, but the pCO2 is indicating one direction (e.g. acidosis) and the HCO3- is indicating another (e.g. alkalosis)

For example, pH of 7.49, pCO2 high, HCO3- very high

MEMORY TRICK: 35 and 45 have 3, 4, and 5, if you want to extend the chain, just add 2 and 6

The correct answer is A. Our patient should have a partially compensated process because it’s acutely affecting him. His body is likely unable to respond to the increased demands that he is placing on his muscles in the Leadville 100 race. Lactic acidosis is likely in this scenario. The lactic acid buildup causes a metabolic acidosis and is normally remedied by oxygen and ensuring that there is good blood flow to the affected areas.

The correct answer is A. Our patient should have a partially compensated respiratory acidosis because it’s acutely affecting her. Her body is trying to respond to decreased oxygen absorption and increased CO2 retention because of the pulmonary edema (fluid on the lungs). She will breathe quicker and her kidneys will retain more HCO3- to balance the respiratory acidosis.

pH: up

PaCO2: down

HCO3: Variable

pH: down

PaCO2: up

HCO3: Variable

pH: up

PaCO2: Variable

HCO3: up

pH: down

PaCO2: Variable

HCO3: down

Metabolic acidosis

Respiratory acidosis

Do not report results

Respiratory alkalosis

Metabolic alkalosis

Mixed acidosis

• indwelling arterial catheter in the radial artery: Note: these are places of error.
• Test is performed on Heparinized Whole Blood
• Collection is in a glass syringe with lyophilized heparin
• Specimen is stable on ICE for 1 hour and at RT for 30 minutes

pH > 7.45 and a pCO2 < 35

• wrong patient drawn
• inappropriate draw technique
• failure to follow protocol for drawing specimen
• introducing air into the syringe
• exposing the specimen to air
• delays in transport
• not keeping sample cold during transport
• failure to check patient demographics
• failure to mix sample properly
• failure to remove all air bubbles
• failure to remove fibrin clots

• Creating a short sample
• failure to perform quality control
• failure to perform maintenance
• failure to perform calibration

• reporting wrong results to the clinician
• transcription mistakes
• failure to interpret instrument flags or warning something may be wrong

! Two points of calibration are required every eight hours and one point calibration at least every four hours. Because of electrode drift slow up ward or down ward drift.

An increase in extracellular H+ ions will drive K+ out. The cell is nice enough to offer to take some of the burden of harboring the extra H+, but it does so in exchange for K+ to keep electrical neutrality

The high H+ concentration in the tissues draws the HCO- out of the cells and sucks the Cl- intracellularly

The lower H+ concentration in the lungs pulls the HCO- back into the cells and pumps the Cl- out

Primary Respiratory Alkalosis - Cause: Blow off CO2

By product Response: Compensatory Metabolic Acidosis - Excrete more HCO3- in the urine

Primary Respiratory Acidosis - Cause: Can’t get rid of enough CO2

Response: Compensatory Metabolic Alkalosis - Retain more HCO3- in the kidneys

Primary Metabolic Acidosis - Cause: Ethanol causes a lactic acidosis

Response: Compensatory Respiratory Alkalosis - Breathe quickly to release extra H+

Primary Metabolic Alkalosis - Cause: Loss of Hydrochloric Acid in vomitus

Response: Compensatory Respiratory Acidosis - Breathe slowly to retain H+

Metabolic alkalosis

Respiratory acidosis

Mixed acidosis

Respiratory alkalosis

Mixed alkalosis

Respiratory acidosis

Bellow 7.4= acidosis

above 7.4= alkalosis

then the cause is some sort of respiratory process

then you should think of metabolic causes.