Acid-Base Regulation - Quiz 4 Flashcards

1
Q

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

A

40 nEq/L

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2
Q

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

A

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

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3
Q

What is an acid?

A

Proton Donor

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4
Q

What does the Henderson-Hasselbalch equation describe?

A

Relationship b/t pH, PaCO2, and Serum Bicarb

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5
Q

What is the Solubility Coefficient for CO2?

A

0.03 mmol/mmHg

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6
Q

What is a base?

A

Proton Acceptor

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7
Q

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

A

Act as Buffers to minimize pH changes

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8
Q

When are pH buffers most efficient?

A

When pH = pKA

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9
Q

What are the pH Body Buffers?

A

Bicarb - strongest ECF buffer

Hgb

Proteins

Phosphate

Ammonia

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10
Q

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

A

Chemical Acid-Base Buffers of Body Fluid

Respiratory Center

Kidneys - slowest, but strongest regulator

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11
Q

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

A

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

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12
Q

What is the pKa of Bicarb?

A

pKa = 6.1

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13
Q

How do the Kidneys increase Bicarb Reabsorption during Acidosis?

A
  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
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14
Q

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

A

Sodium-Hydrogen Counter-Transport

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15
Q

How much Filtered Bicarb is reabsorbed in the Proximal Tubule?

A

80-90 %

The rest reabsorbs in the Distal Tubule

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16
Q

By which mechanism is H+ secreted in Distal Tubule?

A

H+ Pump

17
Q

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

A

K+ is exchanged for H+

18
Q

How does Phosphate play a role in Acid Excretion?

A

HPO42- combines w/ the H+ in the Tubule Fluid to form H2PO4- which CANNOT be reabsorbed and gets trapped in urine

19
Q

Why is Phosphate effective as a buffer in acidic urine?

A

Phosphate has pKA of 6.8

20
Q

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

A

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

21
Q

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

A

NH4 Excretion

22
Q

What are the common situations in which Alkalosis occurs?

A

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

23
Q

What is Base Excess?

A

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

(+) = Metabolic Alkalosis

(-) = Metabolic Acidosis

24
Q

What causes Increased H+ Secretion & Bicarb Reabsorption?

A

↓ECF

↑Angiotensin II

↑Aldosterone

Hypokalemia

Hypocalcemia

25
Q

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

A

~ 0.5

26
Q

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

A

~ 0.5 mEq/L

27
Q

How is Metabolic Acidosis treated?

A

Treat Underlying Cause

Sodium Bicarb (Dont give to pts w/ Resp Failure)

Dialysis

28
Q

How is Alkalosis treated?

A

IV HCl

Spironolactone

Treat Underlying Problem

29
Q

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

A

Doubles Cerebral Blood Flow

30
Q

How is the Anion Gap calculated?

A

Na+ - [Cl- + HCO3-]

Normal: 7 - 14 mEq/L

31
Q

Why does acidosis occur w/ a High Anion Gap?

A

H+ consumes and ties up all the Bicarb

Occurs w/ DKA, Uremia, and Lactic Acidosis

32
Q

What causes Metabolic Acidosis w/ a Normal Anion Gap?

A

Renal Tubular Acidosis

Diarrhea

Carbonic Anhydrase Inhibition

Uteral Diversion

Early Renal Failure

Hydronephrosis

HCl

Saline

33
Q

What toxins cause a High Anion Gap Acidosis?

A

Methanol

Ethylene Glycol

Salicylates

Paraldehyde

34
Q

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

A

Bicarb increases by 1 mEq per 10 mmHg of CO2

35
Q

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

A

Bicarb increases 4 mEq per 10 mmHg in CO2

36
Q

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

A

CO2 decreases 1.2x the decrease in Bicarb

37
Q

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

A

Bicarb decreases 2 mEq/L per 10 mmHg in CO2

38
Q

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

A

Bicarb decreases 2 mEq/L per 10 mmHg in CO2

39
Q

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

A

CO2 increases 0.7x the increase in Bicarb