Fluid and Electrolytes Exam 3 Flashcards
Total body water
60% of weight of 70kg adult male around 42L
2/3 intracellular
1/3 extracellular
total body water content ______ with age, so babies and children…
declines with age, so babies and children have more % than adults
Older adult changes that make them prone to dehydration?
lower % total body water
increase in adipose and decrease muscle
renal decline
diminished thirst perception
*all of these make the elderly prone to dehydration
osmosis
movement of water down concentration gradient…area of lower solute concentration to higher solute concentration
osmotic forces
amount of hydrostatic pressure required to overcome osmotic movement of water
movement of fluid from the capillary into the interstitial space
filtration
movement of fluid from the interstitial space into the capillary
reabsorption
Forces favoring filtration (movement into interstitial space from capillary) or forces apposing reabsorption
capillary hydrostatic pressure (blood pressure)
interstitial oncotic pressure (water pulling)
Forces opposing filtration or forces favoring reabsorption (movement into the capillary)
plasma (capillary) oncotic pressure (water pulling)
interstitial hydrostatic pressure
major forces for filtration and reabsorption are those ______ the capillary = ?
within…= capillary hydrostatic pressure (filtration) and capillary oncotic pressure (reabsorption)
Accumulation of fluid in the interstitial spaces. Causes?
Edema
see slide 12 for causes
Lymph obstruction causes
decreased transport of capillary filtered protein, which causes an increase in tissue oncotic pressure
remember that increased capillary permeability can cause edema how? And what causes this?
loss of plasma protein to interstitial space and therefore decreases capillary oncotic pressure
*causes of this are burns and inflammation (injury)
Edema can be _____ or ______
localized or generalized
local - limited to site of trauma or specific organ system (sprained ankle, cerebral edema, pulmonary edema, pleural effusion, pericardial effusion, and ascites)
generalized - dependent edema, third spacing
Third space =
interstitial space, pleural space, pericardial space. Therefore, not available for metabolic processes or perfusion.
major intracellular electrolytes
Cation - potassium (K+)
anions - phosphate and organic ions
major extracellular electrolytes
Cation - Na+
anions - Cl-, bicarb HCO3-
sodium regulates osmotic forces, thus
water
Sodium roles?
neuromuscular irritability, acid-base balance, cellular reactions, and transport of substances
what is sodium regulated by?
aldosterone and natriuretic peptides
normal amount of sodium in the blood?
135-145 mEq/L
primary anion in ECF
chloride - and it provides electroneutrality
chloride does what with sodium? and what with bicarb?
CHLORIDE FOLLOWS SODIUM, AND VARIES INVERSELY WITH BICARBONATE
A mineralocorticoid steroid synthesized and secreted by the adrenal cortex
aldosterone
when is aldosterone secreted?
SECRETED WHEN SODIUM LEVELS ARE DEPRESSED, POTASSIUM LEVELS INCREASE, OR RENAL PERFUSION IS DECREASED
aldosterone secretion leads to?
SODIUM AND WATER REABSORPTION BACK INTO THE CIRCULATION AND POTASSIUM AND HYDROGEN SECRETION TO BE LOST IN URINE
when is RENIN released? where is renin released from?
SNS activation or decreased perfusion/blood pressure int he renal vasculature…this leads to release of renin from juxtaglomerular cells of the kidney
renin stimulates release of _______
ANGIOTENSIN I (inactive polypeptide)
what converts angiotensin I to angiotensin II
ACE - angiotensin converting enzyme from the lungs (in pulmonary vessels)
two major functions of angiotensin II
vasoconstriction, and release of aldosterone in the adrenal glands
NATURAL ANTAGONIST to RAAS
atrial natriuretic peptide (ANP) and brain natriuretic peptide (BNP) - BNP actually produced by myocardial ventricles
what do BNP and ANP do?
decrease blood pressure, and increase sodium and water excretion
when are BNP and ANP released?
RELEASED WHEN THERE IS INCREASED ATRIAL PRESSURE (INCREASED VOLUME) EX. CHF
DECREASE IN BLOOD PRESSURE DECREASE ATRIAL PRESSURE AND THEREFORE ________ RELEASE OF ANP AND BNP
INHIBITING
*negative feedback
water balance is regulated by two things
thirst perception (osmolality and baroreceptors) and ADH
slide 21-22
When is ADH released? (also called arginine vasopressin)
IS RELEASED WHEN THERE IS AN INCREASE IN PLASMA OSMOLALITY, DECREASE IN CIRCULATING BLOOD VOLUME, OR DECREASE IN BP WHICH ALL RESULT IN DECREASED ATRIAL PRESSURE AND ULTIMATELY SECRETION OF ADH
what does ADH do?
INCREASES WATER REABSORPTION by increasing permeability of renal tubules and collecting ducts of kidneys
baroreceptors cause release of?
baroreceptors
what is osmolality and what are normal values?
is the number of particles per kg of water (mOsm/kg) does not involve particle size
normal - 275 to 295 mOsm/kg
isotonic alterations
When are isotonic fluids used?
total body water change with proportional electrolyte change (NO CHANGE IN CONCENTRATION)
-hemorrhage, severe wound drainage, excess diaphoresis, intestinal losses, and decreased fluid intake
hypernatremia >147 can cause what?
intracellular dehydration, convulsions, pulmonary edema, hypotension, tachycardia
- remember hypernatremia is related to water loss or sodium gain.
- I’m not sure that hypernatremia actually causes hypotension or can be caused by dehydration…this can also cause tachycardia
hyperchloremia - levels, occurs with? s/s?
levels exceed 105 meq/L
occurs with hypernatremia or bicarb deficit
no specific s/s
water deficit s/s
dehydration - isotonic dehydration
pure water deficit is rare - are hypertonic and seen in comatose and paralyzed patients
hypernatremia, hypotension, weak pulse, elevated hematocrit and serum sodium levels, h/a, dry skin, and dry mucous membranes
hypotonic alterations - what happens with hyponatremia and hypotonic ECF
sodium deficits with hypotonic alterations in ECF cause?
d/t over dilution of Na+ d/t excess water in the ECF, this causes hyponatremia
-hyponatremia decreases the ECF osmotic pressure (plasma hypoosmolality) and water moves into the cell (water osmosis - water moves from lower concentration to higher concentration) so this causes cell to expand/swell (this is BOLD)
DILUTIONAL HYPONATREMIA caused by?
excess TBW in relation to total body sodium or shift of water from ICF to ECF (mannitol for acute kidney failure, increased ICP, eye pressure)
HYPOTONIC HYPONATREMIA caused by?
TBW exceeds increase in sodium although both are increased; severe congestive HF and ARF
HYPERTONIC HYPONATREMIA caused by?
shift of water from ICF to ECF in cases of hyperglycemia, hyperlipidemia, and hyperproteinemia
s/s of hyponatremia?
lethargy, h/a, confusion, apprehension, seizures, and coma
hypocholremia results from? number?
usually the result of hyponatremia or elevated bicarb
serum <97mEq/L
some causes - vomiting, metabolic alkalosis, CF
remember DI can cause
loss of water, inability to concentrate urine. Large amounts of dilute urine excreted
*DI caused by lack of ADH or kidneys can not properly respond to it
syndrome of inappropriate ADH (SIADH) - what does it cause?
causes water excess bc there is an excess in production of ADH
this causes hyponatremia (dilutional)
manifestations: cerebral edema, muscle twitching, h/a, and weight gain
major intracellular cation
K+ (3.5-5)
what things help facilitate K+ into the cell
aldosterone, insulin, epinephrine, and alkalosis
what things cause K+ to flow out of the cell
insulin deficiency, aldosterone deficiency, acidosis, and strenuous exercise
Potassium regulates ____ osmolality and deposits ______ in liver and skeletal muscle cells
ICF osmolality and deposits glycogen in liver and skeletal muscle cells
Hypokalemia causes and symptoms
What kind of wave on ECG?
hyperaldosterone state and respiratory alkalosis are two causes but there are others
membrane hyperpolarization causes: decreased muscular excitability, skeletal muscle weakness, smooth muscle atony, cardiac dysrhythmias, U wave on ECG
Hyperkalemia causes?
rarely caused by efficient renal excretion
caused by: (the ones I can’t recall) hypoaldosterone state, hypoxia, acidosis, insulin deficiency, cell trauma
s/s of hyperkalemia
Mild attacks: easier to initiate action potential - tingling of lips and fingers, restlessness, intestinal cramping and diarrhea, peaked T wave on ECG
More severe attacks: with cardiac action potential initially easier to reach AP, but as K+ increases more myocytes are less likely to generate an action potential (cardiac standstill)
*other s/s of severe: muscle weakness, loss of muscle tone, flaccid paralysis, cardiac arrest
Where is calcium located? Normal serum concentration? Necessary for?
most calcium located in the bone as hydroxyapatite
-99% in bone, 1% in plasma and body cells
normal calcium level is 8.5-10.5
*necessary for: structures of bones & teeth, blood clotting, hormone secretion, cell receptor function, muscle contractions
Phosphate located where? Necessary for? Relationship with calcium?
85% found in bone
needed for high-energy bonds in creatinine phosphate and ATP and acts as an anion buffer, and needed for muscle contraction energy
if the concentration of Ca2+ increases, the concentration of phosphate decreases (inverse relationship)
Calcium and phosphate regulated by three hormones
parathyroid hormone (PTH) - increases plasma calcium levels via kidney reabsorption; secreted in response to low calcium
Vitamin D: fat-soluble steroid hormone; increases calcium absorption from GI
Calcitonin - decreases plasma calcium levels (secreted by C-cells of thyroid gland)
hypocalcemia - what causes it? s/s?
less than 8.5, caused by: inadequate intake or absorption, decreased PTH and vit D, blood transfusions
increased neuromuscular excitability (partial depolarization) = muscle spasms - Chvostek and Trousseau signs, convulsions, tetany
hypercalcemia - causes and s/s
greater than 12
caused by hypereparathyroidism, bone metastasis, exceess vitamin D, immobilization, acidosis
s/s: decreased neuromuscular excitability, muscle weakness, kidney stones, constipation, heart block
hypophosphatemia caused by and s/s?
causes: intestinal malabsorption and renal excretion, vitamin D deficiency, antacid use, alcohol abuse
manifestations: diminished release of oxygen, osteomalacia (soft bones), muscle weakness, bleeding disorders (platelet impairment), leukocyte alterations
muscle weakness is a s/s*
from internet (not necessary to know for class): Phosphate deficiency commonly impairs neurologic function, which may be manifested by irritability, paresthesias, confusion, seizures, and coma. Peripheral neuropathy and ascending motor paralysis, similar to Guillain-Barré syndrome, may occur.
hyperphosphatemia - causes, s/s + high phosphate levels r/t _____ calcium levels
causes: exogenous or endogenous addition of phosphate to ECF, long-term use of phosphate enemas or laxatives, renal failure
HIGH PHOSPHATE LEVELS R/T LOW CALCIUM LEVELS
Manifestations: same as hypocalcemia with possible calcification of soft tissue (tetany, muscle spasms)
chloride is a _____ ion and is important in fluid and electrolyte balance and in gastric juice
reciprocally follows changes in ________
also tends to follow ______
extracellular (think sodium chloride)
reciprocally follows changes in bicarb ion
tends to follow sodium
From internet: *needed for: blood pH maintenance, fluid and electrolyte balance (blood pressure, etc.)
Magnesium is an _______ cation
stored mostly where? interacts with? concentration? needed for?
intracellular cation
stored in mostly muscle and bones
interacts with calcium
concentration of 1.8-2.4 mg/dL
is a co-factor in intracellular reactions, protein synthesis, nucleic acid stability, and neuromuscular excitability (increases)
hypomagnesemia often associated with?
hypocalcemia and hypokalemia
neuromuscular irritability, tetany, convulsions, increased reflexes (this is the opposite of hypokalemia)
hypermagnesemia often from? associated with?
often from renal failure, skeletal muscle depression
associated with: muscle weakness, hypotension, respiratory depression, bradycardia (decrease excitability)
