Acid-Base Regulation - Quiz 4

Question 1

What is the Normal amount of H⁺ in the ECF?

Answer 1

40 nEq/L

Question 2

The Lower & Higher Limit of pH at which a person can live for a few hours is ___ & ___ respectively.

Answer 2

The Lower & Higher Limit of pH at which a person can live for a few hours is 6.8 & 8.0 respectively.

Question 3

What is an acid?

Answer 3

Proton Donor

Question 4

What does the Henderson-Hasselbalch equation describe?

Answer 4

Relationship b/t pH, PaCO₂, and Serum Bicarb

Question 5

What is the Solubility Coefficient for CO₂?

Answer 5

0.03 mmol/mmHg

Question 6

What is a base?

Answer 6

Proton Acceptor

Question 7

What is the role of Weak Acids or Bases in regards to pH?

Answer 7

Act as Buffers to minimize pH changes

Question 8

When are pH buffers most efficient?

Answer 8

When pH = pKA

Question 9

What are the pH Body Buffers?

Answer 9

Bicarb - strongest ECF buffer

Hgb

Proteins

Phosphate

Ammonia

Question 10

What are the Primary Systems that regulate H⁺ and Prevent Acidosis/Alkalosis?

Answer 10

Chemical Acid-Base Buffers of Body Fluid

Respiratory Center

Kidneys - slowest, but strongest regulator

Question 11

True or False: The Bicarb buffer is effective Against both Metabolic & Respiratory acid-base imbalances.

Answer 11

FALSE - Bicarb is effective against Metabolic, but not Respiratory acid-base imbalances

Question 12

What is the pKa of Bicarb?

Answer 12

pKa = 6.1

Question 13

How do the Kidneys increase Bicarb Reabsorption during Acidosis?

Answer 13

1. CO₂ + Water = H₂CO₃ (Carbonic Acid)
2. H₂CO₃ —> H⁺ + HCO₃^-
3. H⁺ secreted into Proximal Tubule & Bicarb is Reabsorbed
4. H⁺ in Proximal Tubule combines w/ Filtered Bicarb = H₂CO₃^-
5. Carbonic Anhydrase replaces CO₂ by Splitting Bicarb into CO₂ & Water

Question 14

By which mechanism is H⁺ secreted into the Tubular Fluid?

Answer 14

Sodium-Hydrogen Counter-Transport

Question 15

How much Filtered Bicarb is reabsorbed in the Proximal Tubule?

Answer 15

80-90 %

The rest reabsorbs in the Distal Tubule

Question 16

By which mechanism is H+ secreted in Distal Tubule?

Answer 16

H⁺ Pump

Question 17

How is H⁺ secreted into the Tubular Fluid in the Collecting Duct?

Answer 17

K⁺ is exchanged for H⁺

Question 18

How does Phosphate play a role in Acid Excretion?

Answer 18

HPO₄^2- combines w/ the H⁺ in the Tubule Fluid to form H₂PO₄^- which CANNOT be reabsorbed and gets trapped in urine

Question 19

Why is Phosphate effective as a buffer in acidic urine?

Answer 19

Phosphate has pKA of 6.8

Question 20

How does Ammonium (NH₄) work as a Buffer in the Collecting Tubules vs the Proximal, Distal, & TAL?

Answer 20

Collecting Duct - Ammonia (NH₃) combines w/ H⁺ to make NH₄, then excreted. Bicarb is made in the process

Proximal, Distal, & TAL - NH₄ is made from Glutamine, then excreted. Bicarb is made in the process

Question 21

What is the main mechanism of Acid Elimination w/ Chronic Acidosis?

Answer 21

NH₄ Excretion

Question 22

What are the common situations in which Alkalosis occurs?

Answer 22

Sodium Depletion/Contraction Alkalosis - More sodium goes into Proximal Tubule & Co-Transports Chloride. Bicarb is reabsorbed in exchange w/ Chloride. This happens w/ chronic diuretics.

Increased Aldosterone - Increases Na reabsorption & H⁺ secretion in the Distal Tubule

Question 23

What is Base Excess?

Answer 23

Amount of Acid/Base needed to return pH back to 7.4

(+) = Metabolic Alkalosis

(-) = Metabolic Acidosis

Question 24

What causes Increased H⁺ Secretion & Bicarb Reabsorption?

Answer 24

↓ECF

↑Angiotensin II

↑Aldosterone

Hypokalemia

Hypocalcemia

Question 25

How much does the PaCO₂ increase w/ a 1 mEq/L increase in Bicarb?

Answer 25

_~ 0.5

Question 26

How does Potassium Levels change w/ a 0.1 increase in pH?

Answer 26

_~ 0.5 mEq/L

Question 27

How is Metabolic Acidosis treated?

Answer 27

Treat Underlying Cause Sodium Bicarb (Dont give to pts w/ Resp Failure) Dialysis

Question 28

How is Alkalosis treated?

Answer 28

IV HCl Spironolactone Treat Underlying Problem

Question 29

How is the Cerebral Blood Flow affected by reducing ventilation by half & doubling PaCO₂?

Answer 29

Doubles Cerebral Blood Flow

Question 30

How is the Anion Gap calculated?

Answer 30

Na⁺ - [Cl^- + HCO₃^-] Normal: 7 - 14 mEq/L

Question 31

Why does acidosis occur w/ a High Anion Gap?

Answer 31

H⁺ consumes and ties up all the Bicarb Occurs w/ **DKA, Uremia, and Lactic Acidosis**

Question 32

What causes Metabolic Acidosis w/ a Normal Anion Gap?

Answer 32

Renal Tubular Acidosis Diarrhea Carbonic Anhydrase Inhibition Uteral Diversion Early Renal Failure Hydronephrosis HCl Saline

Question 33

What toxins cause a High Anion Gap Acidosis?

Answer 33

Methanol Ethylene Glycol Salicylates Paraldehyde

Question 34

In *Acute* Respiratory Acidosis compensation, how much does the Bicarb increase for every 10 mmHg increase in CO₂?

Answer 34

Bicarb increases by 1 mEq per 10 mmHg of CO₂

Question 35

In *Chronic* Respiratory Acidosis compensation, how much does the Bicarb increase for every 10 mmHg increase in CO2?

Answer 35

Bicarb increases 4 mEq per 10 mmHg in CO₂

Question 36

For Metabolic Acidosis compensation, what happens to the CO₂ when the Bicarb Decreases?

Answer 36

CO₂ decreases 1.2x the decrease in Bicarb

Question 37

In *Acute* Respiratory Alkalosis compensation, how much does the Bicarb decrease for every 10 mmHg decrease in CO₂?

Answer 37

Bicarb decreases 2 mEq/L per 10 mmHg in CO₂

Question 38

In *Chronic* Respiratory Alkalosis compensation, how much does the Bicarb decrease for every 10 mmHg decrease in CO₂?

Answer 38

Bicarb decreases 2 mEq/L per 10 mmHg in CO₂

Question 39

For Metabolic Alkalosis compensation, what happens to the CO₂ when the Bicarb Increases?

Answer 39

CO₂ increases 0.7x the increase in Bicarb