4 Acid - Base

Question 1

Henderson-Hasselbalch describes the relationship between…

Answer 1

pH, PaCO2, and serum Bicarbonate

Question 2

Solutions of weak acids or bases act as ______ as they minimize ___ changes by donating or accepting electrons.

Answer 2

Buffers, pH

Question 3

Buffers are most efficient when ….

Answer 3

pH = pKa

Question 4

What is the pKa of bicarbonate?

Answer 4

6.1

Question 5

Bicarbonate is a good buffer for what two reasons?

Answer 5

• Is present in > concentrations in the ECF.

- PaCO2 and HCO3 are closely regulated by the lungs and kidneys.

Question 6

What do the kidneys do to compensate during acidosis?

Answer 6

> HCO3 re-absorption

Question 7

H+ is ______ during HCO3 re-absorption in the ________.

Answer 7

Secreted, proximal tubule.

Question 8

What facilitates the reaction between CO2 and H20 to form carbonic acid?

Answer 8

Carbonic anhydrase

Question 9

For every HCO3 re-absorbed, one ____ is secreted.

Answer 9

Hydrogen

Question 10

Carbonic acid is a ______

Answer 10

Weak acid

Question 11

HCO3 is the ______ ______ of carbonic acid.

Answer 11

Conjugate base

Question 12

Where is 80-90% of bicarbonate reabsorbed.

Answer 12

Proximal tubule (10-20% reabsorbed in distal tubule)

Question 13

What is an important tubular fluid buffer?

Answer 13

Ammonium (NH4)

PT, Thick Loop, DT

Question 14

What is NH4 synthesized from?

Answer 14

Glutamine

Question 15

What is generated when NH4 is synthesized from glutamine?

Answer 15

HCO3

Question 16

How is the production of NH4 (ammonium) in the collecting tubules (duct?) different than in the PT, thick loop, and DT?

Answer 16

H combines with NH3 (ammonia) to form NH4. This process also generates HCO3

Question 17

With chronic acidosis, the dominant mechanism by which acid is eliminated is the excretion of what?

Answer 17

NH4 (ammonium)

Question 18

Metabolic alkalosis is mainly possible in what two situations?

Answer 18

• Na depletion (occurs with long term diuretic use)(“contraction alkalosis”)
• Increased aldosterone (Conn’s syndrome)

Question 19

What causes metabolic alkalosis?

Answer 19

• Loss of acid from extracellular space
• Excessive HCO3
• Chronic hypercapnia

Question 20

PaCO2 > ___ mmHg per __ mEq/L increase in HCO3. (Metabolic Alkalosis)

Answer 20

0.5-0.6, 1

Last two digits of the pH should approximate the HCO3 + 15

Question 21

PaCO2 < ___ mmHg per __ mEq/L decrease of HCO3. (Metabolic acidosis)

Answer 21

1.2, 1

Question 22

What 3 diseases cause elevated anion gap metabolic acidosis?

Answer 22

Uremia
Ketoacidosis
Lactic acidosis

Toxins (methanol, ethylene glycol, salicylates)

Question 23

K > __mEq/L for each __ unit decrease in pH.

Answer 23

0.6, 0.1

Question 24

A normal metabolic acidosis anion gap is usually seen with:

Answer 24

Hyperchloremia
(Renal tubular acidosis, diarrhea, carbonic anhydrase inhibition, early renal failure, HCL administration, saline administration)

Question 25

In ACUTE respiratory acidosis, expect a __ mEq/L increase in HCO3 for every __ mmHg increase in CO2

Answer 25

1, 10

Question 26

In CHRONIC respiratory acidosis, expect a __ mEq/L increase in HCO3 for every __ mmHg increase in CO2

Answer 26

4, 10

Question 27

In metabolic acidosis, expect CO2 to decrease ___ times the decrease in HCO3

Answer 27

1.2

Question 28

In ACUTE respiratory alkalosis, expect a __ mEq/L decrease in HCO3 for every __ mmHg decrease in CO2

Answer 28

2, 10

Question 29

In CHRONIC respiratory alkalosis, expect a __ mEq/L decrease in HCO3 for every __ mmHg decrease in CO2

Answer 29

4, 10

Question 30

In metabolic alkalosis, CO2 will increase ___ times the increase in HCO3

Answer 30

0.7

Question 31

Why would the body > H+ secretion and HCO3 reabsorption?

Answer 31

Because of…
Increased: PCO2, H, Angiotensin 2, Aldosterone
Decreased: K, Extracellular fluid volume, HCO3

Question 32

Why would the body < secretion of H and HCO3 reabsorption?

Answer 32

Because of…
Increased: HCO3, extracellular fluid volume, K
Decreased: Angiotensin 2, Aldosterone, H, PCO2