exam II Flashcards
the major intracellular cation is ___ and the normal value is ___
potassium
3.5-5.0 mM/L
the major extracellular cation is ____ and the normal value is ___
sodium
136-145 mM/L
the major extracellular anion is ___ and the normal value is ___
chloride
90-109 mM/L
what is the end point of a mercurimetric chloride assay?
violet blue color -> complex of mercury and diphenylcarbozone
what two cations are most likely to be ordered to determine the cause of cardiac tetany?
calcium and magnesium
be able to calculate the anion gap if given values for sodium, potassium, chloride, and carbon dioxide. be able to correlate abnormal anion gaps with other test results (such as BUN) or with instrument/technologist error.
Na+ - (Cl- + HCO3)= 8-18 mmol/L
(Na+ + K+ ) - (Cl- + HCO3) = 12-20 mmol/L
to what does % saturation of transferrin refer? what is the normal value?
% saturation = serum Fe/ TIBC X 100
20-50%
what is hypokalemia?
low serum potassium
decreased dietary intake, vomiting, renal dysfunction, arrythmias
if tetany is due to calcium, what specific fraction of calcium is involved? will it be increased or decreased?
ionized Ca2+
decreased
what analyte in the blood is used to measure serum phosphorous? what is the normal value for serum phosphorus?
inorganic phosphate
2.7-4.5
why is it important to measure serum magnesium levels?
because cardiac tetany will cause heart to contract and not release causing death
in analyzing calcium by atomic absorption, why is lanthanum added?
to prevent interference of phosphate
calcium exists in serum as ____ and ____ which one is physiologically active?
ionized and protein bound calcium
Ionized (free) calcium
a patient with latic acid acidosis would have an ____ anion gap
increased
what is the purpose of adding magnesium carbonate to an iron binding capacity?
removal of excess unbound iron
what does TIBC measure?
estimates transferrin level in serum
what is the fiske-subbarow method for phosphorus ?
phosphate in the serum is combined with ammonium molybdate to form phosphomolybdate. which is then reduced to molybdenum blue (aminonapthasulfonic acid) which is measured with sphectrophotometry
there is an ____ relationship between serum calcium and phosphorus
reciprocal
what is the normal serum calcium level?
8.4-10.2
what would be the expected test results for calcium and phosphorus in hyperparathyroidism?
increased serum calcium
decreased phosphorus
what is the purpose of adding stannous chloride, ferrous sulfate, and ascorbic acid in the determination of inorganic phosphorus?
reducing agents
name several things that can affect level of circulating calcium
PTH
vitamin D
serum protein levels
bone cell activity
what two hormones control serum calcium levels
PTH
calcitonin
which electrolyte is the chief plasma protein base that helps in maintaining osmotic pressure?
sodium
hemolysis has the greatest effect on serum ____ levels
potassium and magnesium
what is the function of aldosterone?
promotes sodium reabsorption by the kidney which results in
increased water retention
increased blood volume
increased blood pressure
what hormone has the most control over serum phosphate levels?
PTH
what is the normal serum osmolarity?
275-295 mosm/kg of H2O
what are the four main buffer systems of the body
carbonic acid-bicarbonate system
other plasma proteins
hemoglobin
phosphate-phosphoric acid
the pKa of carbonic acid is _____
6.1
what is added to the reaction mixture in calcium determinations to prevent interference by magnesium?
8-hydroxyalquinoline
what component of freezing point osmometer actually measures the sample temperature?
thermistor
what two properties can be used to measure osmolarity?
vapor pressure
freezing point depression
what analytes are the main contributors to serum and urine osmolarity?
electrolytes
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
pH
respiratory acidosis is an excess of ____
exchanged CO2
during the chloride shift, the chloride moves from ___ to ___
what anion is exchanged for chloride?
plasma to RBC
bicarbonate
what buffer system contributes most to the regulation of blood pH? what is the normal ratio of the two of the two portions of the buffer system?
bicarbonate - carbonic acid
20:1
normal blood pH is _____
7.4
most of the CO2 present in the blood is in the form of ____
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
lungs compensate by hyperventilating which gets rid of excess CO2
what is the cause of metabolic alkalosis
excess HCO3
what is p50?
a measure of the affinity of oxygen for hemoglobin & an indicator of the position of oxygen on the dissociation curve
hgb= 50% saturated
26-27mmHg
list several precautions that must be used in handling a specimen for ABGs
must be anaerobic sample
transported within 15 minutes
complete mixing between palms of hands
heparin sample
hyperventilation is a common cause of ____
respiratory alkalosis
what reaction is catalyzed by the enzyme carbonic anhydrase?
formation of carbonic acid from CO2 & H2O
what is the normal range for PCO2?
35-45 mmHg
what is the normal range for pO2?
80-100 mmol/L
in general respiratory acidosis results from____
decreased exchange of CO2
hypoventilation
be able to recognize the henderson-hasselblach equation
pH= pka + log {base(HCO3)} / {acid(carbonic acid)}
a fever of unknown origin would cause a ____ shift on the oxygen dissociation curve while an increased affinity for oxygen causes a ___ shift
right
left
which anticoagulant is preferred for ABG analysis?
heparin
the pO2 electrode is based on the principle of _____
amperometric measurement
what would be the breathing pattern of a patient in respiratory alkalosis?
shallow/rapid (hyperventilation)
what its he compensatory mechanism in respiratory acidosis?
reabsorption of HCO3 in kidneys causes an increased amount of HCO3 in blood
what ABG parameter is most useful in assessing a fire victim?
pO2
how would exposure to air bubbles affect an arterial blood sample?
increased pO2
increased pH
pCO2 decrease
hyperventilation results in the loss of ___
CO2
what events shift the oxygen dissociation curve to the left?
increased: affinity of Hgb for O2/ pH/ CO2
decreased p50, 2,3 -DPG, BT, pCO2
a supercooled solution has a ____ temperature than its freezing points
colder
every mole of solute decreases the freezing point of H20 by ____ degrees
1.86
what is the name of the rapid stirrer mechanism in an osmometer?
vibrator
what are the four forms of CO2 in the blood?
bicarbonate
carbonic acid
dissolved CO2
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?
carboxyhemoglobin
sulfhemoglobin
methemoglobin
how should the sample of an ABG measurement ben mixed?
roll between palms
name several suitable sites for ABG draws
radial
brachial
femoral
temporal
normal value of pH
7.35-7.45
normal value of pO2
80-100
normal value of pCO2
35-45
normal O2 saturation
95-100
normal HCO3
22-26
if pH is decreased
acidosis
if pH is increased
alkalosis
example:
pH=7.5
pCO2=44
HCO3= 30
pH is increased and bicarbonate is increased
this suggests metabolic alkalosis
