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Renal > Lecture 3 - Anesthesia & Renal Physiology: Regulation of Acid-Base Balance > Flashcards

Lecture 3 - Anesthesia & Renal Physiology: Regulation of Acid-Base Balance Flashcards

1
Q

T/F: Acid-base physiology is all about the K+ ion concentrations.

A

FALSE (…is all about H+ ion,,,)

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2
Q

Normal ECF H+ concentration is ~ ____ nEq/L since these numbers are awkward to use, the __ scale is favored.

A
  • 40

- pH

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3
Q

An acid is defined as a proton (H+) ______ while a base acts as a proton ________.

A
  • donor

- acceptor

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4
Q

A strong acid almost completely ________into H+ and a ________ anion WHILE a strong base avidly _____ H+ ion.

A
  • dissociates
  • conjugate
  • binds
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5
Q

T/F: A weak acid or base reversibly donates or accepts a proton.

A

TRUE

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6
Q

T/F: A weak acid of base makes for a good buffer.

A

TRUE

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7
Q

Based on the Henderson Hasselbalch equation we know that the pH of a solution is related to the ratio of the __________ anion to the _______________ acid.

A
  • dissociated

- undissociated

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8
Q

T/F: Buffers are most efficient when the pH is equal to the pKa.

A

True

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9
Q

What are the human body’s buffers:

A
  • Bicarbonate (H2CO3/HCO3)
  • Hemoglobin
  • Intracellular proteins
  • Phosphate
  • Ammonia
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10
Q

T/F: The bicarbonate buffer is effective against respiratory disturbances but not to metabolic acid base disturbances.

A

FALSE (…effective against metabolic but not respiratory acid base disturbances.)

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11
Q

What is the pKa of bicarbonate?

A

6.1

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12
Q

Why bicarbonate a good buffer if the pH is 6.1:

A

Present in high concentrations in the ECF and because PaCO2 and HCO3 are closely regulated by the lungs and kidneys.

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13
Q

How does renal system compensate during acidosis?

A

-Increased HCO3 reabsorbtion

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14
Q

What are the steps the renal system goes through to reabsorb bicarbinate:

A

Step 1: CO2 combines with water to form H2CO3 which rapidly dissociates into H+ and HCO3.

Step 2: H+ is secreted into the proximal tubule and bicarbonate is reabsorbed to blood

Step 3: H+ in the tubule combines with filtered HCO3 to form carbonic acid

Step 4: Carbonic anhydrase hydrolyzes this to water and CO2 which goes into the cell replacing the original CO2.

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15
Q

Over __ to __ % of filtered bicarbonate is reabsorbed in the proximal tubule.

A

80

90

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16
Q

Over __ to __ % of filtered bicarbonate is reabsorbed in the distal tubule.

A

10

20

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17
Q

T/F: In the distal tubule a H+ pump exists which can establish a steep gradient for acidifying urine.

A

TRUE

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18
Q

H+ secreted in tubule lumen can combine with HPO4^2 to form H2PO4 that is NOT _________ and becomes _______ in urine

A
  • reabsorbable

- trapped

19
Q

Phosphate is an effective buffer in the ________ fluid.

A

tubular

20
Q

Phosphate has a pK of ___ which in acidic urine allow to be more _________ buffer.

A
  • 6.8

- effective

21
Q

Kidneys replenish extracellular ______.

A

HCO3

22
Q

What is the ammonium synthesized from:

A

glutamine

23
Q

Ammonium (NH4) is important tubular fluid buffer in the:

A
  • Proximal tubular
  • Thick ascending loop
  • Distal tubular
24
Q

What is also synthesized in the production of ammonium (NH4):

A

bicarbonate

25
Q

Where is ammonium produced in the kidneys?

A

-collecting tubules

26
Q

Metabolic alkalosis is mainly possible in what two situations?

A
  1. Na+ depletion where more sodium is reabsorbed in the proximal tubule, and as this occurs Cl- moves with it to preserve electoneutrality thus as Cl- in the tubule decreases HCO3- must be reabsorbed. This is a so call “contraction alkalosis” that can occur with LONG TERM DIURETIC USE.
  2. Increased aldosterone (mineralocorticoid) activity increases Na+ reabsorbtion and H+ secretion in the distal tubule
27
Q

A base excess that is positive would indicate ______ ________.

A

-metabolic alkalosis

28
Q

A base excess that is negative would indicate _______ _________.

A

-metabolic acidosis

29
Q

Potassium increases ___ mEq/L for each ___ unit decrease in pH (Physiologic effects of acidosis).

A
  • 0.6

- 0.1

30
Q

Physiologic effects of acidosis are:

A
  • Rightward shift is seen in the oxyhemoglobin dissociation curve
  • Cardiac contractility is decreased
  • There is decreased responsiveness to catecholamines
31
Q

What is the equation of anion gap?

A

Anion gap = [Na+] - ([Cl-] + HCO3-])

32
Q

What is the normal value for anion gap?

A

7-14

33
Q

T/F: An acidosis with a high anion gap is caused by relatively strong nonvolatile acids.

A

TRUE

34
Q

What are some substances that cause a high anion gap?

A
  • Uremia
  • Diabetic ketoacidosis
  • Lactic acidosis
35
Q

In a high anion gap the __ ion consumes HCO3- and an ____________ anion accumulates and takes the place of bicarbonate.

A
  • H+

- accuulates

36
Q

A normal anion gap acidosis the ___ takes the place of the HCO3.

A
  • Cl-
37
Q

What are some causes of normal anion gap acidosis:

A
  • diarrhea (GI loss of bicarb)

- Renal loss or HCO3-

38
Q

How would you treat metabolic acidosis?

A
  • Treat underlying cause (Hypovolemia, anemia, cardiogenic shock)
  • NaHCO3 (Do not give to patient with respiratory failure as CO2 will go up)
  • Refractory acidosis may require dialysis
39
Q

How would you treat alkalosis?

A
  • IV HCl (rare cases)
  • Spironolactone if increased mineralocorticoid activity
  • Stop diuretics
  • (Treat Hypokalemia) Hypokalemia will also augment H+ secretion
  • Stop NG suction
40
Q

What would be the expected level of compensation for respiratory acidosis?

A

Acute: 1meq/L increase in HCO3- for every 10 mmHg increase in CO2

Chronic: 4 meq/L increase in HCO3- for every 10mmHg increase in CO2

41
Q

What would be the expected level of compenstion for metabolic acidosis?

A
  • CO2 decrease 1.2 X the decrease in HCO3-
42
Q

What would be the expected level of compensation for respiratory alkalosis?

A

Acute: 2 meq/L decrease in HCO3- for every 10 mmHg decrease in CO2

Chronic: 4 meq/L decrease in HCO3- for every 10mHg decrease in CO2

43
Q

What would be the expected level of compensation for metabolic alkalosis?

A

CO2 increase by 0.7 X the increase HCO3-

Renal (5 decks)

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