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
Potassium Electrolyte Balance
Required for glycogen & glucose deposition in liver & skeletal muscles cells
Maintains resting membrane potential
Kidney is most efficient regulator of K+ balance in the distal tubules.
Changes in pH affect K+ balance
ECF: 4.2
ICF: 150
Hypokalemia
Potassium deficiency <3.5 mEq/L
Caused by dietary deficiency, increase entry of K+ into cells & increased losses of K+
Loss of K+ from body stores are due to GI & renal disorders, diarrhea, intestinal drainage tubes, laxative abuse
Manifestations: neuromuscular & cardiac effects most common symptoms, but mild loss is usually asymptomatic, skeletal muscle weakness, loss of smooth muscle tone, delays repolarization
Hyperkalemia
Elevated ECF potassium > 5.5 mEq/L
Rare
Caused by increase intake, shift of K+ from cells to ECF or decreased renal excretion
Shift of K+ into ECF occurs with cellular trauma, increased permeability, acidosis, insulin deficiency or cell hypoxia, burns, massive crushing injuries.
Manifestations: neuromuscular irritability, restlessness, diarrhea, cramping, muscle weakness, loss of muscle tone & paralysis (severe!), rapid repolarization
Magnesium Electrolyte Balance
Causes meuromuscular excitability, role in smooth muscle contraction & relaxation
ECF: 2
ICF: 24
Calcium Electrolyte Balance
Structure for bone & teeth, cofactor for blood clotting, required for hormone secretion
ECF: 5
ICF: 0
Bicarbonate Electrolyte Balance
ECF:24
ICF:12
Hydrogen Ion Concentrations
Maintain membrane potential integrity
Regulates speed of nerve impulse conduction & muscle fiber contraction
Maintains speed of enzyme reactions
Increased H+ = Increased acidity = Decreased pH
pH
Measures [ ] of H+ in fluids
(acidic)0-14(alkaline)
Normal pH of arterial blood is 7.35-7.45
Body Acids exist in 2 forms: Volatile (Can be eliminated as CO2 gas)–> Carbonic acid can be eliminated in lungs & non-Volatile (can be eliminated in kidney) –> sulfuric, phosphoric acids are excreted via kidneys with regulation of bicarbonate
Buffering Systems
Buffer binds excess H+ or OH- without a significant change in pH
Most important = carbonic acid-bicarbonate system & hemoglobin
Hypermagnesmia
Caused by renal failure, adrenal insufficiency
Causes: excess nerve function, loss of deep tendon reflexes, GI effects, hypotension, bradycardia, resp distress
Hypomagnesmia
Due to malnutrition, malabsorption, alcoholism, loo diuretics
Causes behavioral changes, increased reflexes, hypotension, tachycardia
Hypercalcemia
Due to hyperparathyroidism, bone metastases with Ca2+ reabsorption, excess vitamin D
Causes fatigue, weakness, impaired renal function, kidney stones, osteopoerosis
Hypocalcemia
Due to inadequate intestinal absorption, deposition of Ca2+ into bone or soft tissue, decreased vitamin D, dietary deficiencies
Manifestations: increased neuromuscular excitability, muscle spasm, hyperactive bowel, convulsions & tetany
Metabolic Acidosis
Systemic increase in H+ due to increase of non-carbonic (Non-volatile) acids or loss of bicarbonate from ECF
Ex: lactic acidosis, myocardial infarction, hard core diet, kidney dysfunction
Non-Compensated: pH=Less than 7.35, CO2=normal, HCO3- = lower than 22
Compensated: pH=normal, CO2 = less than 35 (hyperactive breathing to lessen CO2), HCO3- = normal levels (conserve HCO3- & eliminate H+ ions in kidneys)
Metabolic Alkalosis
Elevation of HCO3- usually due to excesssive loss of metabolic acids (vommitting, kidney HCO3- reabsorption, resucettation, hypereliminatation
Non-compensated: pH= greater than 7.45, CO2=normal, HCO3-= above 27
Compensated: pH=normal, CO2=above 45 (conservation of CO2, breathing suppressed), HCO3-= normal (eliminate HCO3- in kidney & conserve H+)
Respiratory Acidosis
Elevation of CO2 due to alveolar hypoventilation
COPD, pneumonia, emphysema, smoking, asthma, fractured ribs.
Non-compensated: pH= less than 7.35, CO2= greater than 45, HCO3-=normal
Compensated: pH =normal, CO2= greater than 23, HCO3-=greater than 27 (Kidneys conserve HCO3- & eliminate H+, no resp compensation)
Respiratory Alkalosis
Depression of CO2 due to alveolar hyperventilation
Caused by anxiety, fever, pain, high altitude, hyperthyroidism.
Non-Compensated: pH=greater than 7.45, CO2= less than 35, HCO3-=normal
Compensated: pH=normal, CO2= normal,HCO3-=less than 22 (kidneys Conserve H+ & eliminate HCO3-, no resp compensation)
Compensation
Renal & respiratory adjustments to changes in pH
Correction
Values for both components of the buffer pair (Carbonic acid & bicarbonate) return to normal levels
