chapter 6 fluid and electrolytes Flashcards
Equal solute concentrations, causes no fluid shifts
Isotonic fluid
lowe solute concentration
fluid shifts out
hypotonic
higher solute concentration
fluid shifts in
hypertonic
triggered by decrease blood volume and osmolarity
Thirst mechanism
Promotes reabsorption of water in the kidneys
Antidiuretic hormone
Increases reabsorption of sodium and water in the kidneys
Aldosterone
Stimulates renal vasodilation and suppresses aldosterone, increasing urinary output
Atrial natriuretic peptid
excess fluid in the interstitial space
edema
excess fluid in the intravascular space
hypervolemia or fluid volume excess
excess fluid in the intracellular space
water intoxication
manifestations as peripherial edema, periorbital edema, anasarca, cerebral edema, dyspnea, bounding pulse, tachycardia, JVD, HTN, polyuria, rapid weight gain, crackles, and bulging fontanelles
Fluid Excess
dehydration, hypovolemia or fluid volume deficit, can occur independently without electrolyte defects.
decrease in fluid level leads to increase in level of blood solutes
cell shrinkage
hypotension
Fluid deficit
positively charged electrolytes
cations
negatively charged electrolytes
anions
normal 135-145
most significant cation and prevalent electrolyte of extracellular fluid
controls serum osmolality and water balance
facilitates muscles and nerve impulses
main source is dietary intake
excreted thru the kidneys and GI tract
Sodium
excessive sodium
Hypertonic IV saline (3% saline)
causes fluid shifts
HYPERnatremia
serum osmolarity decreases
anorexia, GI upset, poor skin turgor, dry mucous membranes, BP changes, pulse changes, edema, headache, lethargy, confusion, diminished deep tendon reflexes, muscle weakness, seizures, and coma
HYPOnatremia
normal 98-108 mineral electrolyte Major extracellular anion found in gastric secretions, pancreatic juices, bile, and csf main source is dietary intake excreted thru the kidneys
chloride
normal 3.5-5
primary intracellular cation
electrical conduction, acid-base balance, and metabolism
can’t fluctuate much without causing serious issues
Potassium
normal 4-5
found in the bone and teeth
role in blood clotting, hormone secretion, receptor functions, nerve transmission, and muscular contraction
inverse relationship with phosphorus
synergistic relationship with magnesium
absorbed thru the GI tract (small intestines)
Calcium
normal 2.5-4.5
found in bones, small amounts in bloodstream
role in bone and tooth mineralizaton, cellular metabolism, acid-base balance, and cell membrane formation
excreted thru the kidneys
phosphorous
normal 1.8-2.5 intracellular cation stored in bone and muscle cardiac rhythm excreted thru kidneys
magnesium
reflects hydrogen concentrations
pH
chemicals that combine with an acid or a base to change pH
Buffers
most significant in the extracellualar fluid
forms from carbon dioxide reacting with water
carbonic anhydrase causes carbonic acid to separate into hydrogen and bicarbonate
carbonic anhydrase in the lungs allow for CO2 excretion and in the kidneys allows for hydrogen excretion
Bicarbonate-carbonic acid system
similar to the bicarbonate-carbonic acid system
high concentrations in the intracellular fluid
act as weak acids, and some act as weak bases
primarily works in the kidneys by accepting or donating hydrogen
Phosphate system
primarily occurs in the capillaries
acidity and hypoxia cause hemoglobin to release the oxygen
hemoglobin then becomes a weaker acid, taking up extra hydrogen
binding with oxygen makes hemoglobin more prone to release hydrogen
hydrogen reacts with bicarb to form carbonic acid, which is converted to carbon dioxide and released into the alveoli
Hemoglobin system
most abundant buffering system
proteins can act as an acid or a base by binding to or releasing hydrogen
occurs in the intracellular and extracellular spaces
hydrogen and CO2 diffuse across the cell membrane to bind with protein inside the cell
albumin and plasma are the primary buffers in the intravascular space
protein system
manages pH by altering CO2 excretion
speeding will excrete more CO2 decreasing acidity and vice versa
uses chemoreceptors
responds quickly, but is short lived
respiratory regulation
alters the excretion or retention of hydrogen or bicarb
more effective because it permanently removes hydrogen
responds slowest, but lasts the longest
renal regulation
results from a deficiency of bicarb or an excess of hydrogen
Metabolic Acidosis
bicarb and chloride results are added together and subtracted from the sodium
normal 6-9
anion gap
results from excess bicarb or deficient acid or both
metabolic alkalosis
results from CO2 retention, which increases carbonic acid
respiratory acidosis
results from excess exhalation of CO2, which leads to carbonic acid deficits
Respiratory Alkalosis
respiratory and metabolic disorders resulting in an acidotic or alkalotic state
both the respiratory and renal systems demonstrate an imbalance of acid or base
mixed disorders
