Class 5 Flashcards
Distribution of Body Fluids
Total body water = 60%
Intracellular fluid = 40%
Extracellular fluid = 20% (includes interstitial, intravascular & transcellular fluid)
Factors Influencing Body Fluid Imbalances
Association of Na+ & H2O (maintains water balance)
Defects in mechanisms controlling fluid volume & [Na+] (ADH–> conserves water & thirst reflex)
Osmotic gradients –> water shift between intra - extracellular space**
Hydrostatic gradients –> fluid pressure, shifting water between intravascular & interstitial space,(capillary bp, capillary oncotic pressure, interstitial hydrostatic pressure & interstitial oncotic pressure)
Children & elderly are at risk for fluid imbalances
Fluid Imbalances
Isotonic
Hypertonic
Hypotonic
Isotonic
Changes in ECF are accompanied by proportional changes in electrolytes so osmolarity remains the same
NO CHANGE!
Hypertonic
Extracellular Na+ is higher than water
SHRINKING! as water moves out of the cell towards Na+
Hypotonic
Extracellular Na+ is lower than water
SWELLING! As water moves into the cell where the Na+ is
Isotonic Fluid Volume Loss/Isotonic Dehydration
Caused by: hemorrhaging, diarrhea, large wounds or burns (loss of electrolytes), kidney dysfunction, third spacing (inappropriate movement of fluid into transcellular spaces)
Manifestations: Thirst, dry mucous membrane, turgor is tense, drop in BP & increased heart rate, fontanel in newborns is caved in, high levels of bilirubin
Isotonic Fluid Volume Excess/Isotonic Overload
Caused by: hyperaldosteronism (continually conserves water), excess intake of water & Na+ (exercising), intravenous fluids
Manifestations: pulse is strong & bounding, extended neck veins, weight gain (1L of water = 1kg), pulmonary edema (SOB, lying on back is painful), Hematocrit (proportion of RBC) dehydrated = increase, overhydrated = lowered
Role of Na+
Maintain water & electrolyte balance
Assist in acid/base balance
Promotes neuromuscular response
Hypertonic Imbalances
Osmolarity of ECF is elevated above normal due to excess Na+ in ECF or ECF water deficit
- Excess Na+: caused by hyperaldosteronism without access to water, Na+ [ ] foods, renal failure, Manifestions: hypervolemia & hypernatremia >147 mEq/L(muscles weakness, seizures, agitation) - Water deficit: caused by lack of water access, kidney disease (disuria) & hyperventilation (lose water through exhalation or fever). Manifestations: hypoglemia, intracellular dehydration (thirst, fever, confusion, coma, oliguria) - Hyperchloremia: too much Na+ & too little bicarbonate
Hypotonic Imbalances
Osmolarity of ECF is decreased below normal levels due to Na+ deficit (< 135 mEq/L), water excess
- Na+ deficit: caused by profuse sweating, burns, vomiting, diarrhea (pure sodium deficits), hypoaldosteronism. Manifestations: hyponatriemia, confusion, seizures & coma - Water Excess: caused by excess hypotonic (IV) solutions, tap water edema, psychiatric disorders (leading to continuous drinking), decreased urine formation (syndrome of inappropriate secretion of ADH). Manifestations: cellular swelling
Edema
Accumulation of fluid in interstitial spaces
Caused by increase in capillary hydrostatic pressure (bp) due to excess volume or venous obstruction, decrease in plasma oncotic pressure (loss of plasma albumin production, plasma proteins), increase in capillary permeability & lymph obstruction (inability to absorb interstitial fluid & small amount of proteins)
Occurs in protein-losing kidney disease, allergic reaction, radical mastectomy (removal of breast & lymphnodes)
Pitting Edema
Edema gravitates to area where gravity is pulling (like the feet)
Sodium Electrolyte Balance
Works with K+& Cl- to maintain neuromuscular irritability for conduction of nerve impluses
Hormonal regulation of Na+ is accomplished by aldosterone (conserves water)
ECF: 142
ICF: 12
Chloride Electrolyte balance
Provides electroneutrality in relation to Na+
Follows active transport of sodium passively
Varies inversely with changes of bicarbonate
ECF: 103
ICF: 4