Exam 4 Chemistry Review/Study Questions Part 1

List 3 functions of electrolytes
Water balance, acid-base balance, muscle contraction
Name the major cation of extracellular fluid:
Na
Name the major cation of intracellular fluid:
K
Name the major anion of extracellular fluid:
Cl
Name the major anion of intracellular fluid
PO4
When sodium is reabsorbed in the tubules, what 2 electrolytes will be secreted?
K & H
When sodium is reabsorbed in the tubules, what electrolyte will also be reabsorbed?
Cl
What hormone regulates the reabsorption of Sodium in the distal tubules?
Aldosterone
What hormone regulates the reabsorption of Water in the distal tubules
ADH (vasopressin)
What hormone regulates the reabsorption of Calcium
PTH
For each of the following conditions, indicate if the serum osmolality will be increased or decreased:
Diabetes insipidus
Increased
For each of the following conditions, indicate if the serum osmolality will be increased or decreased:
Water intoxication
Decreased
For each of the following conditions, indicate if the serum osmolality will be increased or decreased:
Dehydration
Increased
For each of the following conditions, indicate if the serum osmolality will be increased or decreased:
Alcohol intoxication
Increased
State the normal range for serum osmolality
275-295 mOsm/kg
State the normal range for urine osmolality
300-900 mOsm/kg
How will an increased osmolality affect the freezing point of a solution?
It will decrease it
State the formula for a osmolal gap
Measured (automated) Osmo minus calculated Osmo
Give a likely explanation for a delta Osmo of:
-5
Error
Give a likely explanation for a delta Osmo of:
5
Normal
Give a likely explanation for a delta Osmo of:
50
Increased (Alcohols, Lactate, Increased Protein/Glucose/Lipids)
What is the most common cause of hypernatremia?
Dehydration
Which electrolyte can cause cardiac arrest if either elevated or decreased?
K
With which electrolyte does chloride “shift” in an attempt to maintain electrical neutrality?
HCO3
As sodium levels become elevated in plasma, what 2 electrolytes will be excreted from the urine to maintain electrical neutrality?
K & H
Of all the electrolytes, which one is most affected by hemolysis?
K
How will blood pH be affected when bicarbonate levels fall?
It will become more acidic
List the 3 hormones responsible for regulating calcium levels.
PTH, Calcitonin, & Vitamin D
How will an elevated albumin level affect the calcium level?
As albumin increases, so will calcium
Which form of calcium should be tested to best ascertain active levels of calcium in the plasma?
Ionized
Which two electrolytes can cause tetany if levels fall too dramatically?
Ca & Mg
In general, what is the relationship between levels of Ca and phosphate?
Inverse (in plasma)
When is lactate formed?
When tissues don’t get enough oxygen, anaerobic glycolysis produces lactic acid.
how are lactate levels useful to the physician?
Used to predict mortality
When is an anion gap usually decreased?
Instrument error or when 1 analyte is above the upper limits of normal
List conditions causing an elevated AG
Alcohols, organic acids, renal failure
As Osmolality Increases, what happens to the following:
Freezing Point
Decreases
As Osmolality Increases, what happens to the following:
Osmotic Pressure
Increases
As Osmolality Increases, what happens to the following:
Boiling Point
Increases
As Osmolality Increases, what happens to the following:
Vapor Pressure
Decreases
What is associated with the following:
Decreased Serum Osmolality
Water Intoxication
Excessive ADH Secretion
What is associated with the following:
Decreased Urine Osmolality
Diabetes Insipidus
Polydipsia
What is associated with the following:
Increased Serum Osmolality
Dehydration
Hyperglycemia
Diabetes Insipidus
Alcohol Intoxication
Renal Failure
What is associated with the following:
Increased Urine Osmolality
Dehydration
Glycosuria
High protein diets causing inc. urine excretion
Proteinuria
What is the formula to calculate osmolality?
2(Na) + Glucose/20 + BUN/3
What should be the range for Normal Delta Osmo?
0-10
If Delta Osmo is a negative number, what should you suspect?
Technical Error
If Delta Osmo is >10, what should you suspect?
Ethanol, Methanol, Ethylene Glycol
Lactic Acid
Hyperlipidemia or Hyperproteinemia
Technical Error
What is the name of the method used to analyze the most common electrolytes?
ISE
What two types of electrodes are used in the ISE method?
Reference & Sample (or indicator)
What titration method can be used to measure chloride in plasma?
Coulometry (outdated)
With what trace metal is chloride mixed in this titration method?
Ag+ (silver ion)
Name the hormone responsible for regulating sodium reabsorption in the renal tubules
Aldosterone
In regards to sample requirements, what is the difference between direct and indirect ISE?
Direct uses undiluted sample
Indirect uses pre-diluted sample
What can Indirect ISE potentially cause?
False decreased sodium if proteins/lipids are too high