Exam II Acid/Base Balance, Electrolytes, Osmometer Flashcards

1
Q

Major intracellular cation

Normal value

A

Potassium

3.5-5.0 mM/L

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2
Q

Major extracellular cation

Normal Value

A

Sodium

136-145 mM/L

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3
Q

Major extracellular anion

Normal Value

A

Chloride

90-109 mM/L

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4
Q

What is the endpoint of mercurimetric chloride assay?

A

when excess Hg2+ forms a complex with an indicator like dyphenylcarbazon, producing a violet-blue color

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5
Q

What two cations are most likely to be ordered to determine the cause of cardiac tetany?

A

calcium

magnesium

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6
Q

calculate anion gap. be able to correlate abnormal anion gaps with other test results (such as BUN) or with instrument/tech errors

A

(Na + K)-(Cl + HCO3) = 12-20mmol/L

Na - (Cl + HCO3) = 8-18 mmol/L

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7
Q

What does %saturation refer to?

Normal value?

A

%saturation= serumFe/TIBC x 100

20-50%

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8
Q

What is hypokalemia?

A

low serum potassium

caused by dietary intake

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9
Q

If tetany is due to calcium, what specific fraction of calcium is involved?
Will it be increased or decreased?

A

Ionized(free) calcium

decreased

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10
Q

What analyte in the blood is used to measure serum phosphorous?
What is the normal value of serum phosphorous?

A

inorganic phosphorous

2.7-4.5 mg%

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11
Q

Why is it important to measure serum magnesium levels?

A

check for tetany due to magnesium deficiency

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12
Q

In analyzing calcium by atomic absorption, why is lanthanum added?

A

to prevent interference of phosphate

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13
Q

Calcium exist in serum as?

Which is physiologically active?

A

ionized(free) and protein bound

free

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14
Q

A patient with lactic acid acidosis would have an (increased/decreased) anion gap?

A

increased

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15
Q

What is the purpose of adding magnesium carbonate to an iron binding capacity?

A

to remove excess unbound iron

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16
Q

What does TIBC measure?

A

estimates transferrin level in serum

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17
Q

In what method is phosphate in serum combined with ammonium molybdate to form phosphomolybdate, which is then reduced to aminonapthosulfonic acid which is measured with spectrophotometery?

A

Fiske-Subbarow method for Phosphorus

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18
Q

Serum calcium and phosphorous have what kind of relationship?

A

reciprocal

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19
Q

What is the normal serum calcium level?

A

8.4-10.2 mg%

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20
Q

What would be the expected test results for calcium and phosphorus in hyperparathyroidism?

A

increase calcium

decrease phosphorus

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21
Q

What is the purpose of adding stannous chloride, ferrous sulfate, and ascorbic acid in the determination of inorganic phosphorus?

A

reducing agents

*reduces phosphomolybdate to aminonapthosulfonic acid

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22
Q

Name several things that can affect the level of circulating calcium

A

Vitamin D
serum protein levels
bone cell activity

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23
Q

What two hormones control serum calcium levels?

A

PTH and Calcitonin

have an antagonistic relationship

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24
Q

Which electrolyte is the chief plasma base that helps in maintaining osmotic pressure?

A

sodium

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25
Q

Hemolysis has the greatest effect on which serum levels?

A

potassium

magnesium

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26
Q

What is the function of aldosterone?

A

promotes sodium by kidneys, which results in increased water retention, blood vol and BP

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27
Q

What hormone has the most control over serum phosphate levels?

A

PTH

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28
Q

What is the normal serum osmolality?

A

275-295 mOsm/kg of H2O

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29
Q

What are the four main buffer systems in the body?

A

carbonic acid-bicarbonate system
hemoglobin buffers
other plasma proteins
phosphate-phosphoric acid system

30
Q

The pKa of carbonic acid is?

A

6.1

31
Q

What is added to the reaction mixture in calcium determinations to prevent interference by magnesium?

A

8-hydroxylquinoline

32
Q

What component of a FP osmometer actually measures the sample temperature?

A

thermistor

33
Q

What two properties can be used to measure osmolality?

A

Freezing point depression

vapor pressure depression

34
Q

What analytes are the main contributors to serum and urine osmolality?

A

electrolytes
sodium
chloride
bicarbonate

35
Q

What is the principle of the freezing point osmometer?

A

freezing point lowered by an amount that is directly proportional to the concentration of dissolved particles in a solution

36
Q

What does the pCO2 electrode actually measure?

A

pH

37
Q

Increase exchange of CO2

A

respiratory acidosis

38
Q

Decrease exchange of CO2

A

respiratory alkalosis

39
Q

What happens in a chloride shift?

What anion is exchanged for chloride?

A

chloride moves from plasma to red cells

bicarbonate

40
Q

What buffer system contributes most to the regulation of blood pH? What is the normal ratio of the two portions?

A

bicarbonate-carbonic acid system

20: 1
bicarb: carbonic

41
Q
  1. 35-7.45

* 7.4

A

normal blood pH

42
Q

Most of the CO2 present in blood is in what form?

A

bicarbonate

43
Q

What substance is necessary for the release of oxygen from hemoglobin?

A

2,3 DPG

44
Q

What happens in the body to compensate for a state of metabolic acidosis?

A

hyperventilation

45
Q

What is the cause of metabolic alkalosis?

A

excess of bicarbonate

46
Q

What is p50?

A

pO2 at 50% saturation of hemoglobin with O2

47
Q

List several precautions in hadling ABG specimens

A

mix well
dont expose to air
transport within 15 min on ice

48
Q

hypervetilation is the most common cause of?

A

respiratory alkalosis

49
Q

What reaction is catalyzed by the enzyme carbonic anhydrase?

A

formation of carbonic acid from CO2 to H2O

50
Q

35-45 mg%

A

pCO2

51
Q

80-100 mg%

A

pO2

52
Q

Respiratory results from what?

A

decrease exchange of CO2

*hypoventilation

53
Q

Henderson-Hasselbalch equation

A

pH=pKa + log{base(bicarb0}/{acid(carbonic}

54
Q

a fever of unknown origin causes what?

increased affinity for oxygen cause…?

A

shift to the Right of the dissociation curve

shift to the Left

55
Q

What anitocagulant is preferred for ABG analysis?

A

heparin

56
Q

The pO2 electrode is based on what principle?

A

Amperometric measurement

57
Q

What would be the breathing pattern of a patient in respiratory alkalosis?

A

shallow, rapid

58
Q

What is the compensatory mechanism in respiratory acidosis?

A

increase of bicarbonate concentration in blood by increased reabsorption in kidneys

59
Q

What ABG parameter is most useful in assessing a fire victim?

A

pO2

60
Q

How would exposure to air bubbles affect an arterial blood sample?

A

Increase pO2, pH

Decrease pCO2

61
Q

What events shift the oxygen dissociation curve to the left?

A

Increase affinity of hemoglobin for O2, pH, CO2

Decrease p50, 2,3DPG, body temp, pCO2

62
Q

Hyperventilation results in a loss of?

A

CO2

63
Q

A supercooled solutions has ? than is freezing point??

A

lower temp

64
Q

Every mole of solute decreases the freezing point of H2O by?

A

1.86 degrees C

65
Q

What is the name of the rapid stirrer mechanism in an osmometer?

A

vibrator

66
Q

What are the four forms of CO2 in the blood?

A

carbonic acid
bicarbonate
dissolved carbon dioxide
carbamino compounds

67
Q

When calcium levels decline, which hormone is secreted to restore normal calcium levels?

A

PTH

68
Q

What gases can be measured by a co-oximeter?

A

sulfahemoglobin
carboxylhemoglobin
methylhemoglobin

69
Q

How should the sample for an ABG measurement be mixed?

A

roll between the palms

70
Q

Name several suitable draw sites for ABG.

A

brachial
radial
femoral
temporal

71
Q

Be able to evaluate the acid-base status of a patient

A

Increase pH

see slide