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Renal - Larmon > Regulation of Acid-Base Balance > Flashcards

Regulation of Acid-Base Balance Flashcards

1
Q

pH is __________ related to the H+ concentration

A

inversely

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2
Q

A low pH corresponds to a ________ H+ concentration and a high pH corresponds to a ________ H+ concentration

A

high / low

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3
Q

The normal pH of arterial blood is ______, whereas the pH of venous blood and interstitial fluids is about ______ because of the extra amounts of _____ _______ released from the tissues to form H2C03 in these fluids.

A

7.4 / 7.35 / carbon dioxide

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4
Q

Because the normal pH of arterial blood is 7.4, a person is considered to have ________ when the pH falls below this value and _________ when the pH rises above 7.4. The lower limit of pH at which a person can live more than a few hours is about ____ and the upper limit is about ____.

A

acidosis / alkalosis / 6.8 / 8.0

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5
Q

An acid is a proton (H+) _______ while a base is a proton ______

A

donor / acceptor

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6
Q

A strong acid almost completely dissociates into ____ and a conjugate _______ while a strong base avidly binds _____

A

H+ / anion / H+

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7
Q

A weak acid or base ______ donates or accepts a proton

A

reversibly

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8
Q

The Henderson–Hasselbalch equation describes the relationship between what?

A

pH, PaC02, and serum bicarbonate

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9
Q

An increase in bicarbonate concentration causes the pH to ______, and shifts the acid-base balance toward _______

A

rise / alkalosis

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10
Q

An increase in PC02 causes the pH to ________ and shifts the acid-base balance towards _______

A

decrease / acidosis

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11
Q

The HC03 concentration is regulated by the ________, whereas the PC02 in extracellular fluid is controled by the rate of _______

A

kidneys / respiration

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12
Q

Based on the H/H 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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13
Q

Solutions of weak acids or bases act as buffers as they minimize pH changes by donating or accepting _________

A

electrons

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14
Q

Buffers are most efficient when ?

A

pH=pKa

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15
Q

When disturbances of acid-base balance result from a primary change in extracellular fluid HC03 concentration, they are referred to as _______ acid-base disorders

A

metabolic

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16
Q

Body Buffers

A

Bicarbonate (H2C03 / HC03), Hgb, intracellular proteins, Phosphate, Ammonia

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17
Q

________ are by far the most powerful of the acid-base regulatory systems

A

kidneys

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18
Q

Three prieary systems that regulate H+ concentration in the body fluids to prevent acidosis or alkalosis

A

the chemical acid-base buffer systems of the body fluids, the respiratory center, and the kidneys

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19
Q

The chemical acid-base buffer systems of the body fluids, which immediately combine with an acid or base to prevent excessive changes in _____ concentration

A

H+

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20
Q

The respiratory center regulates the removal of C02 and therefore ________ from the extracellular fluid

A

H2C03

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21
Q

The kidneys can excrete either ___ or _____ urine, thereby readjusting the extracellular fluid H+ concentration toward normal during acidosis or alkalosis. The kidneys are relatively _____ to respond.

A

acid / alkaline / slow

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22
Q

The bicarbonate buffer is effective against ______ but not ________ acid-base disturbances

A

metabolic / respiratory

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23
Q

The pKa of bicarbonate is _____. Nonetheless it is a good _____ because it is present in high concentration in the _____ and because PaC02 and HCO3 are closely regulated by the ____ and _____.

A

6.1 / buffer / ECF / lungs and kidneys

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24
Q

What is the most powerful extracellular buffer in the body?

A

bicarbonate buffer system

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25
Q

The pH of the extracellular fluid can be precisely controlled by gthe relative rate of removal and addition of ______ by the kidneys and the rate of removal of ______ by the lungs

A

HCO3 / CO2

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26
Q

Keep in mind that for each HCO3 reabsorbed a H+ must be ______

A

secreted

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27
Q

Explain Renal compensation during acidosis

A

Increased HC03 reabsorption: C02 combines with water to form H2C03 which rapidly dissociates into H+ and HC03, H+ is secreted into the PROXIMAL TUBULE and BICARBONATE is reabsorbed to blood, H+ in the tubule combines with filtered HCO3 to form carbonic acid, carbonic anhydrase HYDROLYZES this water and CO2 which goes into the cell replacing original CO2

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28
Q

Review slide 10

A

Review slide 10

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29
Q

The epithelial cells of the proximal tubule, the THICK segment of the ascending LOH, and the early Distal Tubule all secrete ________ into the tubular fluid by ______-_______ counter-transport

A

H+ / sodium-hydrogen

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30
Q

____ to ____% of filtered bicarbonate is reabsorbed in the _______ ______

A

80-90% / proximal tubule

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31
Q

review slide 13

A

intercalated cells of collecting duct

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32
Q

Reabsorption and secretion of bicarbonate involves 4 steps. Step 1: Sodium ions are reabsorbed filtrate in exchange for _____ by a antiport mechanism in the apical membranes of cells lining the renal tubule. Step 2: The cells produce ________ ions that can be shunted to PERITUBULAR CAPILLARIES. Step3: When CO2 is available, the reaction is driven to the formation of ______ ______, which dissociates to form a bicarbonate ion and a hydrogen ion. Step 4: The bicarbonate ion passes into the peritubular capillaries and returns to the blood. The hydrogen ion is _________ into the filtrate, where it can become part of new water molecules and be reabsorbed as such or removed in the _______.

A

H+ / bicarbonate / carbonic acid / secreted / urine

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33
Q

H+ secreted in tubule lumen can combine with HP04 to form H2PO4 that not ________ and becomes trapped in urine

A

reabsorbable

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34
Q

H2P04 is _______ _______

A

dihydrogen phosphate

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35
Q

Phosphate is effective buffer in ______ fluid

A

tubular

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36
Q

Phosphate has a pKa of _____ which in acidic urine allow to be more effective ________

A

6.8 / buffer

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37
Q

Review slides 16 and 17

A

phsophate buffer

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38
Q

Ammonium (NH4) is an important tubular fluid buffer in what areas?

A

PT, thick loop, DT

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39
Q

Ammonium is synthesized from _________ which comese mianly from the metabolism of amino acids in the liver. BICARBONATE is generated in the process

A

glutamine

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40
Q

In collecting tubules production of NH4 by different mechanism. H+ combines with NH3 to form NH4 which is _______

A

excreted

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41
Q

With CHRONIC Acidosis, the dominant mechanism by which acid is eliminated is excretion of _____. This process also provides the most importnt mechanism for generating new _________ during chornic acidosis.

A

NH4 / bicarbonate

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42
Q

With ammonium production and secretioin, NH4 is secreted into the tubular lumen by ____ _______ mechanism in exchange for SODIUM, which is _________. The HCO3 is transported across the ______ __________, along with the reabsorbed Na+, into the INTERSTITIAL fluid and is taken up by the __________ capillaries.

A

counter transport / reabsorbed / basolateral membrane / peritubular

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43
Q

One of the most important features of the renal ammonium-ammonia buffer system is that it is subject to PHYSIOLOGIC CONTROL. An increase in extraceullular fluid H+ concentration stimulates _____ _________ metabolism and, thererfore, increases the formation of _____ and new ______ to be used in H+ buffering; a DECREASE in H+ concentration has the opposite effect.

A

renal gluatamine / NH4 / HCO3

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44
Q

During renal compensation for alkalosis large amounts of ________ can be excreted if necessary

A

bicarbonate

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45
Q

Metabolic alkalosis is mainly possible in 2 situations. What are they?

A

Na+ depeltion, Increased Aldosterone (mineralcorticoid)

46
Q

Metabolic alkalosis due to Na+ depletion happens when more sodium is reabsored in the _______ tubule, and as this occurs _____ moves with it to preserve neutrality, thus as Cl- in the tubule decreases, _________ must be reabsorbed. This is also know as what?

A

proximal / Cl- / bicarb

47
Q

Contraction alkalosis can occur with what?

A

long term diuretic use

48
Q

Metabolic alkalosis due to increased ALDOSTERONE activity increases ____ reabsorbtion and _____ secretion in the DISTAL tubule

A

Na+ / H+

49
Q

_________ __________ is calculated as the urine flow rate multiplied by urinary HCO3 concentration

A

bicarbonate excretion

50
Q

In alkalosis, the loss of _______ helps return the plasma pH towards normal

A

bicarbonate

51
Q

In alkalosis, there is a ________ net acid secretion

A

negative

52
Q

_____ _______ is defined as the amount of acid or base that must be added to return blood pH to 7.4 with PaC02 = 40 mmHg and temp 37 degrees Celsius

A

base excess

53
Q

With base excess, a positive value indicates ______ ______ and a negative value is _____ _______

A

metabolic alkalosis / metabolic acidosis

54
Q

The most important stimuli for increasing H+ SECRETION by the tubules in acidosis are what?

A

An increase in PC02 of the extracellular fluid in respiratory acidosis AND an increase in H+ concentration of the extracellular fluid (decreased pH) respiratory or metabolic acidosis

55
Q

Review slide 22

A

Acid-base balance

56
Q

Situations that generate metabolic alkalosis from LOSS OF ACID FROM THE EXTRACELLULAR SPACE

A

loss of gastric fluid (HCL), acid loss in the urine from increased distal Na+ delivery in presence of hyperaldosteronism, acid shifts into cells, loss of acid into stool

57
Q

Situations that generate metabolic alkalosis from EXCESSIVE HCO3 loads

A

Oral or parenteral HCO3, metabolic conversion of the salts of organic acids to HCO3

58
Q

T/F Metabolic alkalosis occur from Posthypercapnic states?

A

TRUE

59
Q

Factors that generate metabolic alkalosis include vomiting and diuretic administration. MAINTENANCE of metabolic alkalosis depends on continued stimulus, such as renal _________, hypokalemia, hypochloremia, or hypovolemia, for ________ tubular reabsorption of HCO3

A

hypoperfusion / distal

60
Q

Factors that maintain metabolic alkalosis

A

decreased GFR, volume contraction, hypokalemia, passive backflus of HCO3, aldosterone

61
Q

Review proposed mechanisms on slide 24

A

slide 24

62
Q

_________ ____________ is associated with hypokalemia, ionized hypocalcemia, secondary ventricular arrhythmias, increased digoxin toxicity, and compensatory hypoventilation (hypercarbia), although compensation rarely results in PaC02 above _____ mmHg.

A

metabolic alkalosis / 55

63
Q

Alkalmeia may reduce tissue oxygen availability by shifting the oxyhemoglobin curve to the _____ and by decreasing cardiac output

A

left

64
Q

During anesthetic management, inadvertent addition of iatrogenic respiratory alkalosis to pre-existing metabolic alkalosis may produce severe __________ and precipitate cardiovascular depression, dysrhythmias and hypokalemia

A

alkalemia

65
Q

In metabolic alkalosis, The PaC02 increases ___ to ___mmHg per 1 mEq/L increase in HCO3

A

0.5 to 0.6

66
Q

The last two digits of the pH should appoximate the HCO3 + ____

A

15 / example. pH 7.40, so subtract 15 from 40 which is 25 which should approximate what the bicarb is

67
Q

In metabolic acidosis, PaC02 decreases ___ mmHg per 1 mEq/L in HCO3 to a minimum of 10-15 mmHg

A

1.2

68
Q

For metabolic alkalosis, treatment could be expansion of intravascular volume or administration of potassium. Infusion of 0.9% saline will dose-dependentlhy increase serum _____ and decrease serum _____

A

Cl- / HCO3

69
Q

Differential diagonsis of metabolic acidosis with an elevated anion gap are what 3 diseases?

A

uremia, ketoacidosis, lactic acidosis

70
Q

Differential diagonsis of metabolic acidosis with an elevated anion gap can be from what toxins? (4)

A

Methanol, Ethylene glycol, salicylates, paraldehyde

71
Q

Differential diagnosis of metabolic acidosis with a normal anion gap includes what (8)?

A

Renal tubular necrosis, diarrhea, carbonic anyhydrase inhibition, ureteral diversions, early renal failure, hydronephrosis, HCL administration, Saline administration

72
Q

________ ________ occurs as a consequence of buffering by bicarbonate of endogenous acid loads or as a consequence of abnormal external loss of bicarbonate

A

metabolic acidosis

73
Q

Metabolic acidosis associated with a high Anion Gap which is greater than _____ mEq/L, occurs because excess production of decreased excretion of organic acids or ingestion of one of several toxic compounds.

A

13

74
Q

In metabolic acidosis associated with high anion gap, bicarbonate ions are consumed in buffering hydrogen ions, while the associated anion replaces ________ in serum.

A

bicarbonate

75
Q

Physiologic effects of acidosis

A

(1) potassium increases 0.6 mEq/L for each 0.1 unit decrease in pH (2) a rightward shift is seen in the oxy-hemoglobin dissociation curve (3) Cardiac contractility is decreased (4) There is decreased responsiveness to catecholamines

76
Q

In acidosis, there is a net addition of ______ back to the blood as more ____ and urinary titratable acid are excreted.

A

bicarbonate / ammonium

77
Q

Failure of a patient to appropriately hyperventilate in response to metabolic acidosis is physiologically equivalent to ________ ________ and suggests clinical deterioration

A

respiratory acidosis

78
Q

Preoperative assessment should emphasize _______ status and ________ function

A

volume / renal

79
Q

in planning intravenous fluid therapy, consider that balanced salt solutions like LR tend to _________ pH and HCO3 and 0.9% saline tends to ________ pH and HCO3

A

increase / decrease

80
Q

______ should rarely be used to treat acidemia induced by metabolic acidosis

A

Sodium Bicarb (NaHCO3)

81
Q

Treating metabolic acidosis.

A

Treat the underlying cause (hypovolemia, anemia, cardiogenic shock), NaHCO3 (do not give to patient with respiratory failure as C02 will go up, refractory acidosis may require dialysis

82
Q

T/F Although many clinicians choose to administer NaHCO3 to patients with persistent lactic acidosis and ongoing deterioration, there are no clinical trials that demonstrate improved outcome

A

TRUE

83
Q

IV HCL is used in rare cases to treat ________

A

alkalosis

84
Q

If alkalosis is due to increased mineralcorticoid activity what medication may be given?

A

spironolactone

85
Q

________ are the main contributing cause of CHLORIDE sensitive metabolic alkalosis

A

diuretics

86
Q

When diuretics are the cause of metabolic alkalosis _____ is actively reabsorbed secondary to ECF fluid ____________, Cl- goes with it to maintain elctroneutrality and not enough is available so HCO3 is reabsorbed and _____ is secreted

A

Na+ / depletion / H+

87
Q

Hypokalemia will also augment H+ __________

A

secretion

88
Q

Loss of gastric fluid from NG suction or vomiting will cause ________ through loss of HCL

A

alkalosis

89
Q

Is Respiratory Alkalosis ALWAYS characterized by hypocarbia (PaCO2 less than or equal to 35mmHg)

A

yes

90
Q

Respiratory alkalosis is usually characterized by an alkalemic pH of _______

A

> 7.45

91
Q

Can respiratory alkalosis result from an INCREASE in minute alveolar ventilation?

A

Yes

92
Q

Respiratory alkalosis may be a sign of what? (5)

A

pain, anxiety, hypoxemia, central venous systemic disease, systemic sepsis

93
Q

Respiratory alkalosis may produce what? (6)

A

hypokalemia, hypocalcemia, cardiac dysrhythmias, bronchoconstriction, hypotension, and may potentiate the toxicity of digoxin

94
Q

Both brain pH and cerebral blood flow are tightly regulated and respond rapidly to changes in PaC02. Doubling minute ventilation reduces PaC02 to 20 mmHg and _______ cerebral blood flow; conversely, halving minute ventilation _______ PaC02 and _________ cerebral blood flow.

A

halves / doubles / doubles

95
Q

In metabolic acidosis, an excess of H+ over HCO3 occurs in the tubular fluid primarily because of dereased filtration of _________

A

HCO3

96
Q

In respiratory acidosis, the excess H+ in the tubular fluid is due mainly to the rise in extracellular luid PC02 which stimulates _____ secretion

A

H+

97
Q

Review Slides 32 and 33

A

diagnosing acid base disorders. Www.glowm.com/lab_text/item/3

98
Q

Hypobicarbonatemia associated with an increased anion gap is never ________

A

compensatory

99
Q

Metabolic acidosis associated with increased anion gaps require specifc _______

A

treatments

100
Q

Anion gap =

A

[Na+] - ([Cl-] + [HCO3])

101
Q

Normal Anion Gap

A

7-14 mEq/L

102
Q

The anion gap is really a measure of _______ ______

A

unmeasured ions

103
Q

An acidosis with a high anion gap is caused by relatively strong non-volatile acids. In this case H+ consumes HCO3 and an unmeasured anion accumulates and takes the place of ________. Examples?

A

bicarbonate / uremia, DKA, lactic acidosis

104
Q

Three quarters of the normal anion gap consists of ________.

A

albumin

105
Q

Normal anion gap metabolic acidosis is usually sseen with _________

A

hyperchloremia (Cl- takes the place of the bicarbonate ion)

106
Q

Expected level of compensation in ACUTE RESPIRATORY ACIDOSIS

A

expect a 1 mEq/L increase in HCO3 for every 10 mmHg increase in CO2 (usually from 40 mmHg)

107
Q

Expected level of compensation in CHRONIC RESPIRATORY ACIDOSIS

A

expect a 4 mEq/L increase in HCO3 for every 10 mmHg increase in C02

108
Q

Expected level of compensation in METABOLIC ACIDOSIS

A

CO2 decrease 1.2 times the decrease in HCO3 (usually from 24 mEq/L)

109
Q

Expected level of compensation in ACUTE RESPIRATORY ALKALOSIS

A

expect 2 mEq/L decrease in HCO3 for every 10 mmHg decrease in CO2

110
Q

Expected level of compensation in CHRONIC RESPIRATORY ALKALOSIS

A

expect 4 mEq/L decrease in HCO3 for every 10 mmHg decrease in CO2

111
Q

Expected level of compensation in CHRONIC METABOLIC ALKALOSIS

A

CO2 increase by 0.7 times the increase in HCO3

Renal - Larmon (3 decks)

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