Fluid and Electrolytes Flashcards
Body fluid composition = ___ % of body weight
50-60%
Body fluid composition consists of
water, electrolytes, glucose, urea, creatinine
What is in the intracellular fluid
potassium, phosphate, protein, magnesium
What is in extracellular fluid
plasma (intravascular fluid), interstitial fluid (between cells or tissues), transcellular fluid (cerebral, peritoneal, synovial)
Water balance exists when . . .
total water intake and total water loss are equal
what mechanism maintains water balance
homeostatic
An average adult living in a moderate environment takes in about how many ml of water
2500 ml
How does the nervous system regulate fluid balance?
the hypothalamus - thirst and renal excretion
How do arterial baroreceptors regulate fluid balance?
when arterial bp decreases the SNS responds with vasoconstriction; vasoconstriction of renal arteries = a decreased GFR which = reduced urine output which means an increased blood volume
How does the endocrine system regulate fluid balance?
adrenocorticotropic hormone (ACTH)
antidiuretic hormone (ADH or vasopressin) and renin-angiotensin-aldosterone system
What is osmolality?
An estimation of the osmolar concentration of plasma, is expressed as mmol/kg
What is normal range for serum osmolarity?
280-330 mmols/kg
What are crystalloid solutions?
Saline and dextrose solutions
What are examples of colloids?
blood, plasma, albumin, synthetics (such as dextron)
Clinical signs of fluid volume deficit
- decrease skin and tongue turgor
- decreased moisture in mouth (dry mucous membranes)
- severe body fluid loss marked by hematocrit, hemoglobin, creatinine, and BUN are elevated
- decreased urinary output
- specific gravity of urine increased
- postural hypotension - drop in systolic bp of 20mmHg accompanied by tachycardia
what is normal specific gravity of urine?
1.010 - 1.020
Causes of fluid volume excess
increased retention of Na and water and/or decreased excretion of Na and water
What is increased retention of Na and water caused by
HF, liver failure, nephrotic syndrome, glucosteroids, SIADH
What is decreased retention of Na and water caused by
renal failure
What causes edema in fluid volume excess?
accumulation of fluid in the interstitial space - when there is excess in volume, fluid pressure is greater than the colloidal osmotic pressure, therefore more fluid is pushed into the interstitial spaces
increase in hydrostatic pressure in capillaries forces fluid into the interstitial spaces which can occur because of a
mechanical blockage
decrease plasma colloid osmotic pressure from decrease protein content of places leads to fluid flowing from ____ to ____
plasma to interstitial spaces
increase permeability of capillaries allows protein to seep into the ____ ____ and create an ____ pull
interstitial spaces; osmotic pull
What are hypertonic fluids used to treat and why?
symptomatic hyponatremia b/c they have a heavier solute volume
Why are hypotonic fluids used?
Gives more water than electrolytes
what does isotonic mean?
osmotic equilibrium; osmolarity of ICF and ECF are the same means no movement of water
What is the typical fluid requirement for adult per day?
35ml/kg/day
why are electrolytes important
enzyme activities, muscle contraction, and metabolism
What are the extracellular ions
sodium, chloride, calcium
what are the intracellular ions
potassium, magnesium, phosphorus
Normal sodium
135-145
Normal potassium
3.5-5.0
Normal calcium
2.14 - 2.66
Normal magnesium
0.70 - 1.10
Normal chloride
95 - 105
Normal phosphorus
0.8 - 1.6
What is the most abundant extracellular cation
sodium
What is sodium responsible for
amount of water retained or excreted
what is sodium required for
- transmission of impulses across muscles and nerves
- important in acid-base balance
what does sodium combine with to increase or decrease pH
combines with chloride to increase, bicarb to decrease
what is sodium maintained by
GFR and the release of aldosterone
changes in sodium levels alter ____ ____
water balance
low sodium causes kidneys to activate the __________ system
renin-angiotensin aldosterone system
excessive sodium is excreted by the ____
kidneys
what is the most abundant anion in ECF
chloride
chloride works with ____ to regulate body fluids through osmotic pressures
sodium
acid base balance requires that ____ is in balance with ____ and ____
sodium; chloride; bicarb
Potassium is a major intracellular
anion
why is close monitoring of potassium important
b/c the body is intolerant to abnormal levels
what is potassium vital in
cardiac and neuromuscular function b/c it affects muscle contraction
abnormal levels of ____ are the most common electrolyte imbalance in the high acuity patient
potassium
Magnesium ensures ____ and ____ transport across cell membranes
sodium and potassium
what magnesium required for
protein and carbohydrate metabolism
magnesium is important in
nerve cell conduction, transmitting CNS messages, and maintaining neuromuscular activity
phosphate is contained in
bone
phosphate is involved in
energy metabolism
phosphate has an inverse relationship with
calcium
loss of phosphate =
diuresis, malabsorption, overuse antacids
increased phosphate =
renal failure, increased serum calcium
most calcium is located in ____
bone
Calcium is required for
blood coagulation, neuromuscular contraction, enzymatic activities, and bone integrity
serum calcium levels are maintained by ____
kidneys excretion, GI absorption, and bones (mobilization)
calcium is absorbed in intestines only in the presence of
vitamin D
