Intro to Acid-Base

Question 1

General mechanisms that control the pH of the body (8 questions total on Acid-Base)

Answer 1

4 ways the body regulates pH
(CO2) + (H2O) ---> (H2CO3) ---> (HCO3-) + (H+)
Chemical buffer systems
Respiratory buffer system
Liver oxidation of strong acids
Renal mechanisms

Question 2

Chemical buffer systems

Answer 2

Fast-acting. Molecules in the inter/intra cellular that resist pH changes. Phosphate, protein, bicarbonate.

Question 3

The respiratory buffer system

Answer 3

Works quickly (1-3 minutes). CO2 is ACIDIC!!

• Breathing more and deeper “blows off” CO2. So minus acid… makes more basic! (increases pH)
• Breathing shallow and less, retains CO2, and therefore increases acidity (decreases pH)

Question 4

Liver oxidation of strong acids

Answer 4

Don’t wait up, this process takes a bit longer.

• “Substrate oxidation” occurs in the liver:
• Gluconeogenesis and lactate oxygenation occur in liver (processes both consuming H+)

Question 5

Renal mechanisms

Answer 5

This can take hours to days. The kidneys are super, super important in regulating HCO3 in the body

• They reabsorb HCO3 (act as a reservoir for it) OR generate bicarb!
• They can also excrete bicarbonate back into the blood stream from stores.

Question 6

Arterial Blood Gas and usefulness

Answer 6

Components: pH, pCO2, and HCO3-, PO2

-Knowing the patient’s pH (comprised of the HCO3 (basic) and CO2 (acidic) values), in conjunction with the other anion lab values, can give you the clues to find Carmen Sandiego. And whether the patient is acidotic or alkalemic, and if so if the imbalance has a respiratory or metabolic etiology. Compensated or uncompensated.

Question 7

Evaluation of an anion gap and significance of its presence

Answer 7

Textually: The anion gap is the difference between primary measured cations (sodium Na+ and potassium K+) and the primary measured anions(chloride Cl- and bicarbonate HCO3-) in serum.
Significance: The presence of the anion gap points you towards the etiologies of the imbalance
Anion gap acidoses:
-DKA, Starvation, Alcoholic
-Renal Failure/Uremia
-Toxins/drugs

Question 8

Step by step approach to ascertain the presence of an acid base disorder

Answer 8

1. Consider the clinical setting!
2. Is the patient academic or alkalemic?
3. Is the primary process metabolic or respiratory?
4. If metabolic acidosis, gap or non-gap?
5. Is the degree of compensation appropriate?
6. Is more than one disorder present?

Question 9

Acid base disorders

Answer 9

See table