Exam 2 Flashcards
What is the major intracellular cation?
potassium
What is the normal value for potassium?
3.5-5.0 mM/L
What is the major extracellular cation?
sodium
What is the normal value for sodium?
136-145 mM/L or mEq/L
What is the major extracellular anion?
chloride
What is the normal value for chloride?
90-109 mM/L
What is the endpoint of a mercurimetric chloride assay?
violet blue color
What is the violet blue color of a mercurimetric chloride assay a result of?
complex of mercury and diphenylcarbozone
What two cations are most likely to be ordered to determine the cause of cardiac tetany?
calcium and magnesium
To what does %saturation of transferrin refer?
ratio of serum iron to TIBC
What is the normal value of % saturation?
20-50%
What is hypokalemia?
low serum potassium
What are some causes of hypokalemia? (3)
decreased dietary intake, vomiting, renal dysfunction
If tetany is due to calcium, what specific fraction of calcium is involved?
ionized calcium
If tetany is due to calcium, will it be increased or decreased?
decreased
What analyte in the blood is used to measure serum phosphorus?
inorganic phosphate
What is the normal value for serum phosphorus?
2.7-4.5 mg/dL
Why is it important to measure serum magnesium levels?
tetany due to magnesium deficiency
In analyzing calcium by atomic absorption, why is lanthanum added?
to prevent interference of phosphate
Calcium exists in serum as…? (2)
ionized and protein bound
Which of the two types of calcium is physiologically active?
ionized
A patient with lactic acid acidosis would have an increased or decreased anion gap?
increased
What is the purpose of adding magnesium carbonate to an iron binding capacity?
removes excess unbound iron
What does TIBC measure?
estimates transferrin level in serum
What is the Fiske-Subbarow method for phosphorus?
molybdate added to serum to form phosphomolybdate which is reduced to aminonaphthosulfonic acid
What type of relationship exists between serum calcium and phosphorus?
reciprocal
What is the normal serum calcium level?
8.4-10.2 mg/dL
What would be the expected test results for calcium and phosphorus in hyperparathyroidism?
calcium is increased, phosphorus is decreased
What is the purpose of adding stannous chloride, ferrous sulfate, and ascorbic acid in the determination of inorganic phosphorus?
they are reducing agents
What are some things that can affect the level of circulating calcium? (4)
serum protein levels, PTH, bone-cell activity, vitamin D
What two hormones control serum calcium levels?
calcitonin and PTH
Which electrolyte is the chief plasma base that helps in maintaining osmotic pressure?
sodium
What ions does hemolysis have the greatest affect?
potassium and magnesium
What is the function of aldosterone? (4)
increased sodium reabsorption, increased water retention, increased blood pressure, and blood volume
What hormone has the most control over serum phosphate levels?
PTH
What is the normal serum osmolality?
275-295 mosm/kg of water
What are the four main buffer systems of the body?
bicarbonate-carbonic acid, hemoglobin buffer, plasma proteins, phosphoric acid-phosphate buffer
What is the pKa of carbonic acid?
6.1
What is added to reaction mixture in calcium determinations to prevent interference by magnesium?
8-hydroxylquinolone
What component of a freezing point osmometer actually measures the sample temperature
thermistor
What two properties can be used to measure osmolality?
vapor pressure and freezing point depression
What analyses are the main contributors to serum and urine osmolality?
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 the soluteion
What does the PCO2 electrode actually measure?
pH
Respiratory acidosis is an excess of?
carbon dioxide
What is respiratory acidosis due to
decreased exchange of carbon dioxide
During the chloride shift, the chloride moves from where to where?
plasma to cell
What anion is exchanged for chloride?
bicarbonate
What buffer system contributes most to the regulation of blood pH?
bicarbonate-carbonic acid
What is the normal ratio of the two portions of the buffer system?
20:1 if lungs and kidneys are functioning properly
What is pH of normal blood?
7.35-7.45 (slightly alkaline)
Most of the carbon dioxide in the blood is in the form of?
bicarbonate
What substance is necessary for the release of oxygen from hemoglobin?
2,3-DPG
What does DPG stand for?
diphosphoglycerate
What happens in the body to compensate for a state of metabolic acidosis?
hyperventilation
What is the cause of metabolic alkalosis?
excess bicarbonate
What is p50?
PO2 at which hemoglobin is 50% saturated with oxygen
What is the normal range for p50?
26-27 mmHg
What are some precautions that must be used in handling a specimen for ABGs?
anaerobic, transported within 15 minutes, place on ice, heparinized, drawn from the artery, mixed well
Hyperventilation is a common cause of?
respiratory alkalosis
What reaction is catalyzed by the enzyme carbonic anhydrase?
forms carbonic acid from carbon dioxide and water
What is the normal range for pCO2?
25-45 mmHg
What is the normal range for pO2?
80-100 mmHg
In general, respiratory acidosis results from?
decreased exchange of carbon dioxide from lungs resulting in increased carbon dioxide hypoventilation
A fever of unknown origin would cause why type of shift in the oxygen dissociation curve?
shift to the right
What type of shift is caused by an increased affinity for oxygen?
shift to the left
Which anticoagulant is preferred for ABG analysis?
heparin
The pO2 electrode is based on what principle?
amperometric
What would be the breathing pattern of a patient in respiratory alkalosis?
shallow, rapid
What is the compensatory mechanism in respiratory acidosis?
increasing bicarbonate concentration by increasing reabsorption in the kidneys
What ABG parameter is most useful in assessing a fire victim?
pO2
How would exposure to air bubbles affect an arterial blood sample?
pO2 would increase, pH would increase, pCO2 would decrease
Hyperventilation results in the loss of?
CO2
Every mole of solute decreases the freezing point of H2O by how many degrees?
1.86 C
What is the name of the rapid stirrer mechanism in an osmometer?
vibrator
What are the 4 forms of carbon dioxide in the blood?
bicarbonate, carbonic acid, dissolved CO2, carabamino compounds
What percentage of the blood is made up of bicarbonate?
90-95%
When calcium levels decline, which hormone is secreted to restore normal calcium levels?
parathyroid hormone
What gases can be measured by a co-oximeter?
carboxyhemoglobin, sulfhemoglobin, and methemoglobin
How should the sample for an ABG measurement be mixed?
Roll between palms
Name four suitable sites for ABG draws
radial, brachial, femoral, and temporal arteries
What is ceruloplasmin?
transport protein for copper
What disease is ceruloplasmin decreased?
Wilson’s disease
What is oligoclonal banding?
increased CSF IgG and multiple distinct bands in the globulin zone
Where is oligoclonal banding typically seen?
90% of MS patients
What is the normal range of blood pH?
7.35-7.45
What is the normal range for bicarbonate?
22-26
What is the acid-base status of a patient with a decreased pH?
acidosis
What is the acid-base status of a patient with an increased pH?
alkalosis
What does it mean if the pH and pCO2 is the same?
metabolic
What does it mean if the pH and pCO2 is the opposite?
respiratory
What is the Henderson-Hasselbach equation?
pH = pKa + log (base/acid)
What kind of relationship to calcitonin and PTH have?
antagonistic
What events shift the oxygen dissociation curve to the left?
decreased p50 causes an increased affinity of hemoglobin for O2