Electrolytes Flashcards
What electrolyte/s is/are important in the maintenance of myocardial rhythm and muscle contractility?
K, Mg, Ca
What electrolyte/s is/are important in volume and osmotic regulation?
Na
TRUE or FALSE: Sodium can act as a activator
False
Decreased blood volume (dehydration), ____ blood osmolality, ____ ADH (water retention by the kidneys)
Increased, increased
RAAS: angiotensin II causes ____, which ____ blood pressure and secretion of aldosterone, which increases retention of ____.
Vasoconstriction; increases; Na
Urine osmolality is ____ in diabetes insipidus.
Decreased
Primary mechanism for cells to maintain water balance between themselves and their surrounding environment
Na-K-ATPase pump
TRUE or FALSE: Iron overload is observed in patients with hemolytic anemia.
True
Reagent used in the Schales and Schales chloride determination
Mercuric nitrate
Intracellular fluid accounts for about ___ of total body water.
2/3
A 1-2% increase in osmolality causes a fourfold ____ in the circulating concentration of AVP.
Increase
AVP acts by increasing the reabsorption of water in the ____ and ____.
Cortical and medullary collecting tubes
Renin is secreted near the renal glomeruli in response to ____ renal blood flow.
Decreased
2 most frequently used methods for osmolality determination
Freezing point depression and vapor pressure decrease
Operate by freezing point depression and are standardized using sodium chloride reference solutions
Osmometer
Difference between the measured osmolality and the calculated osmolality
Osmolal gap
Na-K-ATPase pump moves ___ Na+ ions out of the cell in exchange for ___ 2 K+ ions into the cell as ATP is converted to ___.
3; 2; ADP
3 processes most important in Na+ regulation:
Intake of water in response to thirst
Excretion of water (largely affected by AVP release)
Blood volume status (affects Na+ excretion through aldosterone, angiotensin II and ANP)
__% to __% of filtered Na+ is reabsorbed in the proximal tubule.
60; 75
Electroneutrality is maintained by either ___ reabsorption or H+ secretion.
Cl-
Treatment for hyponatremia
Fluid restriction and provision of hypertonic saline
AVP receptor antagonist, Conivaptan
A reset osmostat may occur in ____, in which excess aldosterone induces mild hypervolemia that retards AVP release, shifting plasma Na+ upward.
Primary hyperaldosteronism
TRUE or FALSE: Serum, plasma, and urine are all acceptable for Na+ measurements.
True
An ___ plasma K+ decreases the resting membrane potential (RMP) of the cell.
Elevated
Hypokalemia: ____ cell excitability by increasing RMP
Decreases
Under the influence of ____, additional K+ is secreted into the urine in exchange for Na+ in both the distal tubules and the collecting ducts.
Aldosterone
Principal determinant of urinary K+ excretion
Distal nephron
3 factors that influence the distribution of K+ between the cells and ECF:
K+ loss frequently occurs whenever the Na-K-ATPase pump is inhibited by conditions such as hypoxia, hypomagnesemia, or digoxin overdose
Insulin promotes acute entry of K+ into the skeletal muscle and liver
Catecholamines promote cellular entry of K+, while propanolol impairs cellular entry of K+
Alkalemia and insulin ____ the cellular uptake of K+
Increase
In DM, insulin deficiency promotes cellular ____ of K+
Loss
Treatment should be immediately initiated when serum K+ is ____ or greater.
6 - 6.5 mmol/L
Provides immediate but short-lived protection to the myocardium against the effects of hyperkalemia
Ca+
Whole blood samples for K+ determinations should be stored at:
Room temperature
Anticoagulant of choice for K+
Heparin
2 ways Cl- maintains electrical neutrality
Reabsorption with Na+ at the proximal convoluted tubules (Na+ reabsorption is limited by the amount of Cl- available)
Chloride shift
Cl- determination: amperometric-coulometric titration using ___ ions which combine with Cl- to quantitate Cl- concentration
Silver
Most of the HCO3 in the kidneys is reabsorbed by the proximal tubules, with ___% being reabsorbed by the distal tubules.
15
Anticoagulant preferred for Cl- and CO2 determination
Lithium heparin
4th most abundant cation in the body and 2nd most abundant intracellular ion
Magnesium
Approximately 53% of Mg+ found in the body is found in ____.
Bone
TRUE or FALSE: About 2/3 of Mg+ in the serum is bound to albumin.
False
*1/3
TRUE or FALSE: Free Mg+ is the physiologically active form in the body.
True
Organ in charge of overall regulation of body Mg+
Kidneys
Major renal regulatory site of Mg+
Ascending loop of Henle
Normally, about ___% of filtered Mg+ is excreted in the urine per day.
6
What hormone increases the renal reabsorption of Mg+ and enhances the absorption of Mg+ in the intestine?
Parathyroid hormone
What is the normal plasma osmolality?
275-295 mOs/kg of plasma H2O
Sodium and its associated anions account for approximately ___% of the osmotic activity in plasma.
90
ISE with ____ membrane is the routine method for Potassium determination.
Valinomycin
Cl- and Na+ are passively reabsorbed by the ____.
PCT
The Schales & Schales method of Cl determination uses the principle of ____.
Mercurimetric titration
This method for Cl- determination uses mercuric thiocyanate and has a reddish end-product.
Whitehorn titration method
Bicarbonate accounts for more than ___% of total CO2 at physiologic pH.
90
Overall regulation of Mg+ is controlled largely by the ____.
Kidneys
What are the 3 colorimetric methods of Mg+?
Calmagite method
Formazen dye method
Methylthymol method
Titan yellow dye method
What is the reference method for Mg+ & Ca+?
AAS
What are the 2 colorimetric methods of Ca+?
Ortho-cresolphthalein complexone (CPC)
Arsenazo III dye
What are the 2 precipitation & redox titration methods of Ca+?
Clarke-Collip precipitation
Ferro Ham Chloroanilic precipitation
What is the method used and its end-product of PO4- determination?
Fiske-Subbarow; ammonium phosphomolybdate complex/molybdenum blue
