Fluid and Electrolytes Flashcards
(63 cards)
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
