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Final Exam
Electrolytes
116
Chemistry
Graduate
04/15/2013

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Term
Electrolyte are
Definition
solutions containing free ions behaving as electrically conductive media. Because they consist of ions in solution, electrolytes are ionic solutions
Term
Electrolyte solutions are formed when
Definition
a salt is placed into a solvent and the individual components dissociate
Term
Electrolytes are classified
Definition
based on their migration in and electrical field.
Term
Cations migrate towards
Definition
the cathode and are said to be positively charged.
Term
The principle cations in human plasma are
Definition
Na+, K+ Ca++, MG++
Term
Anion migrate towards
Definition
the anode and are said to be negatively charged.
Term
The principle anions in human plasma are
Definition
CL-, HCO3-, So4-,PO4-
Term
Total body water
Definition
includes the water within and outside the cell and that normally found in the gastrointestinal and urogential systems
Term
Total body water is subdivided into two compartments:
Definition
the intracellular fluid (ICF) and the extracellular fluid (ECF)
Term
ECF
Definition
is the medium for all metabolic exchange
Term
ICF
Definition
medium for cellular metabolic reactions
Term
Average total body water
Definition
65%
Term
Total body water varies inversely with
Definition
total body fat
Term
Plasma volume is
Definition
the sole compartment of total body water
Term
Plasma volume percent of total body weight
Definition
5%
Term
Total body water as a percentage of body weight decreases
Definition
during intrauterine development and reaches the normal adult values by age three.
Term
Plasma volumes remain
Definition
constant throughout life
Term
The absolute volume of the water compartments
Definition
all increase with growth.
Term
Plasma is
Definition
mixture of water and macromolucules, i.e., proteins, lipids.
Term
Plasma water refers strictly
Definition
to the aqueous phase
Term
The concentration of ions in the plasma is
Definition
lower than their actual concentration in the plasma water.
Term
The ions are present solely in the
Definition
water phase
Term
Reported concentrations represent
Definition
the ion concentration in the plasma
Term
The actual concentration of the ions in the plasma water impact
Definition
diffusion across the capillary membrane.
Term
Increased concentrations of macromolecules in the plasma will result in
Definition
lower measured ion concentration even though plasma water ion concentrations and activity may be normal.
Term
Donnan’s equilibrium
Definition
requiring that the sum of all charged particles must be equal.
Term
the sum of the cations must
Definition
equal the sum of the anions so no net electrical charge exists
Term
Anion Gap
Definition
The sum of the measured cations (Na+ +K+) exceeds the sum of the measure anions (CL- + HCO3-).
Term
Anion gap indicates
Definition
unmeasured anions are greater than the unmeasured cations.
Term
Increases in the anion gap usually indicates
Definition
an increase in one or more of the unmeasured anions. Used in the differential diagnosis of metabolic acidosis
Term
Anion gap formula
Definition
[Na+] - [Cl-] - [HCO3-]
Term
Reference range Anion Gap
Definition
8 to 16 mmol/l
Term
Major Clinical Uses of the Anion Gap
Definition
To signal the presence of a metabolic acidosis
Help differentiate between causes of a metabolic acidosis: high anion gap versus normal anion gap metabolic acidosis.
Term
In an inorganic metabolic acidosis
Definition
the infused Cl- replaces HCO3 and the anion gap remains normal.
Term
In an organic acidosis
Definition
the lost bicarbonate is replaced by the acid anion which is not normally measured. This means that the AG is increased
Term
Major functions of blood electrolytes
Definition
Maintenance of osmotic pressure
Water distribution
Maintenance of pH
Regulation of the proper function of the heart and muscles
Oxidation-reduction reaction – electron transfer
Catalytic reactions by serving as cofactors for enzymes
Term
Theoretical Osmotic Pressure
Definition
O.P. (t) (mmHg) = 19.3 mmHg/mOsm/L X Osmolality (mOsm/L)
Term
Theoretical osmotic pressure is proportional
Definition
to osmolality.
Term
Osmotic pressure is
Definition
the force that tends to move water from dilute solutions to concentrated solutions
Term
effective osmotic pressure
Definition
When a membrane is permeable to a solute the solute exerts no osmotic pressure across the membrane
Term
The effective osmotic pressure is dependent upon
Definition
the total number of solute particles in solution and the permeability of the membrane to the solute
Term
The higher the permeability of the membrane to the solute
Definition
the lower is the effective osmotic pressure of a solution of that solute at any given osmolality.
Term
Measurements of osmolality measure the
Definition
theoretical not the effective osmotic pressure
Term
hyperosmotic
Definition
A solution with an effective osmotic pressure greater than plasma
Term
hypertonic
Definition
A solution with a theoretical osmotic pressure greater than plasma
Term
Hyposmotic and hypotonic
Definition
refer to solutions with effective and theoretical osmotic pressures less than plasma.
Term
colloid osmotic pressure.
Definition
The effective osmotic pressure of plasma and the interstitial fluid across the capillary membrane
Term
Capillary endothelium are impermeable to
Definition
larger protein molecules (colloids).
Term
These colloids are responsible for
Definition
the effective osmotic pressure between the plasma and the interstitial fluid
Term
Water distribution across the capillary endothelial membrane are controlled by
Definition
the balance between filtration and reabsorption forces
Term
The principle filtration force in the plasma is
Definition
hydrostatic pressure the primary reabsorption force is the colloid osmotic pressure.
Term
Plasma hydrostatic pressure drive water
Definition
out
Term
colloid osmotic pressure draws water
Definition
in
Term
Hydrostatic Pressure
Definition
is the pressure that the fluid exerts on the walls of its container. In human body, the hydrostatic pressure refers to the pressure that the blood exerts on the walls of the arteries and veins.
Term
Osmotic Pressure
Definition
is the pressure required to prevent the flow of water across a semi permeable membrane via osmosis.
Term
Water and solute distribution across the cell membrane depend on
Definition
on the integrity of the cell membrane and on osmotic and electrochemical forces
Term
The permeability of the cell membrane to a solute is directly related to
Definition
the lipid solubility of the solute and inversely related to hydrophilicity and molecule size
Term
Extracellular osmolality is maintained between
Definition
285 and 300 mOsm/L through the balance between water intake an excretion.
Term
Water intake
Definition
Ingestion, Water in foodstuffs and Oxidative metabolism
Term
Water Loss
Definition
Urine, Insensible Perspiration and GI water loss (stool)
Term
Kidney is principally responsible for
Definition
regulating the volume and composition of the body fluids
Term
Insensible Water Loss
Definition
Occurs through the skin and the respiratory tract
Term
Insensible Water Loss varies directly with
Definition
ambient temperature, body temperature and activity
Term
Insensible Water Loss varies inversely with
Definition
ambient humidity
Term
simple dehydration
Definition
Defined as decrease in total body water with a relatively normal total body sodium
Term
simple dehydration results from
Definition
failure to replace obligatory water losses, regulatory failures
Term
simple dehydration associated with
Definition
hypernatremia and hyperosmolarity because water balance is negative and sodium balance is normal
Term
↑ECF osmolality as water is lost results in
Definition
movement of water out of the ICF. Results in a contraction of both the ECF and the ICF.
Term
Dehydration due to Water and Sodium Loss
Definition
Most often dehydration involves a net negative balance in both water and sodium
Term
Hypernatremic (hyperosmolar) dehydration
Definition
water balance is more negative than sodium, most common
Term
Normonatremic (isoosmolar) dehydration
Definition
water and sodium balance are equally negative
Term
Hyponatremic (hypoosmolar) dehydration
Definition
water balance is less negative than sodium balance
Term
Hypernatremic (hyperosmolar) dehydration Changes to Extracellular Volume
Definition
ECF volumes effected the least. ↑ECF Osm. Draws water from the ICF – ICF contracts
Term
Normonatremic (isoosmolar) dehydration Changes to Extracellular Volume
Definition
no change to ECF Osm – no net water flow
Term
Hyponatremic (hypoosmolar) dehydration
Changes to Extracellular Volume
Definition
Greatest effect to ECF volume - ↓Osm. Of ECF causes water to move into the cells – ICF volume expanded
Term
Water intoxication
Definition
Defined as increased total body water
Term
Water intoxication usually results from
Definition
impaired renal excretion resulting from excessive ADH secretion
Term
Water intoxication usually results in
Definition
hyponatremia and hypoosmolality producing a expansion of the ECF and ICF
Term
If Na is normal the ↑ in total body water
Definition
water is confined to the EC
Term
If Na is ↓than the increase in water is
Definition
shared between the ECF and ICF.
Term
Gibbs-Donnan equilibrium
Definition
difference in Na concentration between the ECF and the ISF
Term
Sodium balance is a result of
Definition
carefully controlled intake and output mechanisms
Term
Sodium intake
Definition
food stuffs
Term
Sodium output
Definition
occurs through three primary routes: GI tract, skin, and urine
Term
Sodium concentration in sweat is decreased by
Definition
aldosterone
Term
Sodium concentration in sweat is increased by
Definition
cystic fibrosis
Term
Sodium Loss through the skin can be extensive in
Definition
severe burns and exudative skin lesions
Term
The principle route for sodium excretion
Definition
Kidney
Term
Renal excretion regulated through
Definition
aldosterone
Term
Management of Na+ reabsorption in the distal tubule
Definition
establishes the renal threshold for Na+ - 110mM/L which determine the amount of Na+ excreted in the urine.
Term
Sodium Depletion
Definition
Occurs when the output of sodium exceeds intake
Term
Hyponatremia
Definition
Indicates a decreased plasma sodium concentration
Term
Hyponatremia- Causes
Definition
Sodium deficit greater than water deficit, Fluid Shift – ECF to ICF, Psuedohyponatremia, Water excess greater than sodium excess
Term
Hypernatremia
Definition
Occurs when sodium intake exceeds sodium output usually because of a defect in the homeostatic mechanism
Term
Hypernatremia- conditions
Definition
Cardiac Failure, Liver Disease, Renal Disease (nephrotic syndrome), Hyperaldosteronism, Pregnancy, CHF
Term
Hypernatremia – Causes
Definition
Sodium excess greater than water excess, Water deficits greater than sodium deficits, Hyperventilation, Diabetes insipidus, Osmotic diuresis, Diminished fluid input – diminished thirst, Essential hypernatremia, Certain diarrheal states and vomiting
Term
Specimen for sodium determinations
Definition
serum, plasma whole blood sweat, urine, feces, GI fluids
Term
Factors that increase cellular influx of K+
Definition
Insulin, aldosterone, alkalosis,  adrenergic stimulation
Term
Factors that decrease cellular influx of K+
Definition
Acidosis, alpha adrenergic stimulation, tissue hypoxia
Term
K+ input
Definition
food
Term
K+ output
Definition
GI Tract
Sweat
Urine
Term
Factors regulating distal tubular secretion of K+ include
Definition
Intake of Na+ and K+
Water flow rate in the distal tubules
Plasma levels of mineralocorticoids
Acid-base status
Term
Increased K+ levels produce
Definition
symptoms of mental confusion, weakness, numbness and tingling in the extremities, slowed heart rate, peripheral vascular collapse and cardiac arrest.
Term
K+ excess
Definition
+ levels greater than 7.5 mM/L, <10.0 is fatal
Term
Increased potassium intake
Definition
Diet, Oral supplementation, IV administration, High dose potassium penicillin use, transfusion
Term
Decreased potassium excretion
Definition
Renal Failure, Adrenal failure (hypoaldosteronism), diuretics that block distal K+ secretion (spironolactone), Primary defects in renal tubular handling of K+ secretion.
Term
Causes K+ depletion
Definition
Decreased potassium intake, Increased GI Loss, Increased urinary loss
Term
Hyperkalemia
Definition
Occurs with an increased plasma K+ concentration
Term
Hypokalermia
Definition
Occurs with decrease plasma K+ concentrations
Term
Hyperkalemia – Causes
Definition
Pseudohyperkalemia, Intracellular to extracellular shifts, High potassium intake, and Decreased potassium excretion
Term
Hypokalemia – Causes
Definition
Extracellular to intracellular K+ Shift, Decreased potassium intake, Increased GI Loss, and Increased urinary loss
Term
Specimens for the determination of K+
Definition
serum or plasma must avoid hemolysis.
Term
Chloride
Definition
Major anion of the extracellular fluid
Term
Output of Cl-GI tract, skin, urine
occurs through three principle routes:
Definition
GI tract, skin, urine
Term
Chloride Excess
Definition
Accumulation occurs when intake exceeds output because of some abnormality n homeostatic mechanism
Term
Chloride Depletion
Definition
Occurs when output exceeds intake
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