Exam II Acid/Base Balance, Electrolytes, Osmometer Flashcards by Alex Olsen

Major intracellular cation

Normal value

Potassium

3.5-5.0 mM/L

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Major extracellular cation

Normal Value

Sodium

136-145 mM/L

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Major extracellular anion

Normal Value

Chloride

90-109 mM/L

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What is the endpoint of mercurimetric chloride assay?

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

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

calcium

magnesium

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

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

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

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What does %saturation refer to?

Normal value?

%saturation= serumFe/TIBC x 100

20-50%

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What is hypokalemia?

low serum potassium

caused by dietary intake

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

Ionized(free) calcium

decreased

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

inorganic phosphorous

2.7-4.5 mg%

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Why is it important to measure serum magnesium levels?

check for tetany due to magnesium deficiency

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

to prevent interference of phosphate

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Calcium exist in serum as?

Which is physiologically active?

ionized(free) and protein bound

free

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

increased

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

to remove excess unbound iron

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What does TIBC measure?

estimates transferrin level in serum

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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?

Fiske-Subbarow method for Phosphorus

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Serum calcium and phosphorous have what kind of relationship?

reciprocal

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What is the normal serum calcium level?

8.4-10.2 mg%

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

increase calcium

decrease phosphorus

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

reducing agents

*reduces phosphomolybdate to aminonapthosulfonic acid

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Name several things that can affect the level of circulating calcium

Vitamin D
serum protein levels
bone cell activity

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What two hormones control serum calcium levels?

PTH and Calcitonin

have an antagonistic relationship

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

sodium

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Hemolysis has the greatest effect on which serum levels?

potassium | magnesium

What is the function of aldosterone?

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

What hormone has the most control over serum phosphate levels?

PTH

What is the normal serum osmolality?

275-295 mOsm/kg of H2O

What are the four main buffer systems in the body?

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

The pKa of carbonic acid is?

6.1

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

8-hydroxylquinoline

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

thermistor

What two properties can be used to measure osmolality?

Freezing point depression | vapor pressure depression

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

*electrolytes* sodium chloride bicarbonate

What is the principle of the freezing point osmometer?

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

What does the pCO2 electrode actually measure?

Increase exchange of CO2

respiratory acidosis

Decrease exchange of CO2

respiratory alkalosis

What happens in a chloride shift? | What anion is exchanged for chloride?

chloride moves from plasma to red cells bicarbonate

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

bicarbonate-carbonic acid system 20: 1 bicarb: carbonic

7. 35-7.45 | * 7.4

normal blood pH

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

bicarbonate

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

2,3 DPG

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

hyperventilation

What is the cause of metabolic alkalosis?

excess of bicarbonate

What is p50?

pO2 at 50% saturation of hemoglobin with O2

List several precautions in hadling ABG specimens

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

hypervetilation is the most common cause of?

respiratory alkalosis

What reaction is catalyzed by the enzyme carbonic anhydrase?

formation of carbonic acid from CO2 to H2O

35-45 mg%

pCO2

80-100 mg%

pO2

Respiratory results from what?

decrease exchange of CO2 | *hypoventilation

Henderson-Hasselbalch equation

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

a fever of unknown origin causes what? | increased affinity for oxygen cause...?

shift to the Right of the dissociation curve | shift to the Left

What anitocagulant is preferred for ABG analysis?

heparin

The pO2 electrode is based on what principle?

Amperometric measurement

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

shallow, rapid

What is the compensatory mechanism in respiratory acidosis?

increase of bicarbonate concentration in blood by increased reabsorption in kidneys

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

pO2

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

Increase pO2, pH | Decrease pCO2

What events shift the oxygen dissociation curve to the left?

Increase affinity of hemoglobin for O2, pH, CO2 | Decrease p50, 2,3DPG, body temp, pCO2

Hyperventilation results in a loss of?

CO2

A supercooled solutions has ? than is freezing point??

lower temp

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

1.86 degrees C

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

vibrator

What are the four forms of CO2 in the blood?

carbonic acid bicarbonate dissolved carbon dioxide carbamino compounds

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

PTH

What gases can be measured by a co-oximeter?

sulfahemoglobin carboxylhemoglobin methylhemoglobin

How should the sample for an ABG measurement be mixed?

roll between the palms

Name several suitable draw sites for ABG.

brachial radial femoral temporal

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

Increase pH | ***see slide***