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38 Cards in this Set

  • Front
  • Back
What maintains ICF osmotic balance?
What maintains ECF osmotic balance?
What is net filtration?
The movement of fluid back & forth across the capillary wall.
Why does the plasma fluid leave the (arterial) circulation & enter the interstitial space?
Hydrostatic (arterial) pressure is higher than oncotic pressure.
Why does the plasma leave the interstitial space and enter (venous) circulation?
Osmotic pressure is higher than (venous) hydrostatic pressure.
What is TBW water balance?
Total water intake=total water output.
Sodium accounts for what % of ECF cations?
It's concentration in the serum is much higher than that inside of the cells.
What is a cation?
Positively charged ion.
What do intake & output mechanisms respond to?
Serum osmolality
What is osmolality?
Osmotic concentration; the characteristic of a solution determined by the ionic concentration of the dissolved substances per unit of solvent.
What is plasma osmolality
The osmotic concentration of plasma.
Normally the ionic concentration in the plasma is maintained within a narrow range: 275 to 295 mOsm/kg.
What happens when plasma osmolality increases above normal? (increased sodium decreased H2O)
The sensation of thirst, which stimulates the person to drink fluids.
Antidiuretic hormone is released. ADH prevents loss of water by the kidney. (to try to increase solvent & dilute soluable)
What is the main extracellular cation?
Why will extra sodium in the ECF cause a cell to shrink?
Because only water passes by difusion, and the water is drawn out of the cell in order to try to maintain balance. (sodium cannot be drawn into the cell to try to maintain balance)
Why does a hypotonic ECF cause a cell to swell?
The Na+ concentration in the cell is higher than that of the ECF so H2O difusses into the cell, trying to maintain balance.
What is hypernatremia?
The sodium concentration is high.
>147 mEq/L
What is hyponatremia?
The sodium concentration is low.
<135 mEq/L
The physiologic roles of sodium cations include;
Maintaining the tonicity of ECF.
Regulating acid-base balance by renal reabsorption of Na+ & excretion of H-.
Facilitating nerve conduction & neuromuscular function.
What are the physiologic roles of sodium?
Facilitating glandular secretions (sweat)
Maintaining water balance.
What are some causes of hyponatremia?
Loss from excess sweating, vomiting & diarrhea.
Diuretics combined w/low salt diets.
Renal failure & hormonal imbalances.
What are some causes of hypernatremia?
Insufficient ADH.
Loss of thirst mechanisim.
Watery diarrhea.
Prolonged periods of rapid respiration.
What are some of the effects of hyponatremia?
Nerve conduction impairment.
Fluid imbalances in compartments.
Decreased osmotic pressure in ECF.
Brain cell swelling.
What are some of the effects of hypernatremia?
Fluid shifts out of the cells owing to increased osmotic pressure in ICF or ECF.
Intracellular dehydration.
Thirst, CNS manifestations. Convultions, PE
What are the primary electrolytes found in the ECF & ICF?
sodiuim, potassium, chloride, calcium, magnesium, phosphorus, hydrogen ions & bicarbonate.
What electrolytes are found in ICF?
Potassium (major cation)
Magnesium (major cation)
Phosphate (major anion)
What electrolytes are found in ECF?
Sodium (major cation)
Calcium (major cation)
Chloride (major anion)
Bicarbonate (major anion)
What is ICF compromised of?
Water, Electrolytes, Proteins, Nucleic acids, Lipids, Polysaccharides.
What is ECF compromised of?
Water, Electrolytes, Proteins, Nucleic acids, WBCs, Platelets.
What does tonicity describe?
Relative concentrations of electrolytes (osmotic pressure) on both sides of a semipermeable membrane (the cell or capillary wall)
What are changes in tonicity?
The change in the concentration of solutes w/relation to water.
What is mainly an ECF anion & accounts for 2/3 of all serum anions?
Choride, helps maintain acid-base & H2O balances, influences the tonicity of ECF, facilitates exchange of O2 & CO2 in RBCs, activates salivary amylase.
What is Hyperchloremia?
Too much Na+ or too little HCO3, associated w/use of ammonium chloride diuretics.
What are the S/Sx of a pt w/hyperchoremia?
(not specific) deep, rapid breathing, weakness, & diminished cognitive ability (could lead to coma)
What is hypochloremia?
Associated w/Na+ deficiency,
Causes; ↑ loss of GI fluids, perspiration or renal failure.
What are the manifestations of hypochloremia?
muscle hypertonicity & tetany, shallow, depressed breathing, muscle weakness & twitching.
What is the dominant cation of the ICF compartment?
What is its concentration ICF compared to ECF?
40 X of the ECF
What represents the principal osmotic determinant of cellular volume?