Fluid Balance

Question 1

filtration

Answer 1

liquids moved by pressure (ex: COP, hydrostatic pressure)

Question 2

normal serum osmolarity

Answer 2

275-295 mOsm/kg

Question 3

hyperosmolarity

Answer 3

> 295 mOsm/kg

Question 4

hypoosmolarity

Answer 4

<275 mOsm/kg

Question 5

osmolarity affects

Answer 5

tonicity

Question 6

osmotic pressure

Answer 6

pressure needed to prevent osmosis through a semipermeable membrane
-proportional to the osmolarity of a solution

Question 7

hypotonic solutions

Answer 7

lower osmotic pressure than blood-fluid goes into the ICF and causes cell swelling
-1/2 normal saline
-2.5 dextrose

Question 8

hypertonic solutions

Answer 8

higher osmotic pressure than blood-fluid goes into the ECF and causes cell shrinkage
-5% dextrose normal saline
-5% dextrose lactated ringer

Question 9

fluid is balanced through:

Answer 9

thirst, RAAS, ADH, ANP

Question 10

renin-angiotensin-aldosterone system (RAAS)

Answer 10

decreased perfusion to kidneys>kidneys release renin>renin and angiotensinogen makes angiotensin I>in lungs becomes angiotensin II>angiotensin II makes adrenal cortex (kidney) release aldosterone>aldosterone tells kidney to reabsorb Na+ and excrete K+>water follows Na+ into ECF

Question 11

hyperaldosteronism causes:

Answer 11

too much water because of an excessive amount of Na+

Question 12

antidiuretic hormone (ADH)

Answer 12

secreted by posterior pituitary from increased osmolarity in blood
-increases water retention/ECF water volume

Question 13

atrial natriuretic peptide (ANP)

Answer 13

released by atria, decreases water retention
-inhibits renin secretion
-blocks secretion/action of aldosterone (less Na+ absorption, less water)

Question 14

total gains/losses of fluid in body

Answer 14

2500mL in, 2500mL out

Question 15

hypovolemia causes

Answer 15

excessive fluid losses
-ex: GI losses, hemorrhage, excessive NG suctioning,
inadequate fluid intake
-ex: dysphagia, unconsciousness, reduced thirst sensation, lack of fluids with tube feedings
third-spacing
ex: burns, intestinal obstruction, edema, ascites

Question 16

hypovolemia manifestations

Answer 16

decreased vascular volume
-ex: hypotension, shock, tachycardia
increased serum osmolarity
-ex: thirst, increased hematocrit+blood urea nitrogen
ADH compensation
-ex: decreased urine output, increased osmolarity
impaired body temperature regulation
-ex: fever

Question 17

hypovolemia treatment

Answer 17

oral/parenteral fluids, blood (from hemorrhage), antidiarrheals (from diarrhea), antiemetics (from vomiting), vasopressors (for hypovolemic shock)

Question 18

hypervolemia causes

Answer 18

inadequate Na+ and water elimination
-ex: heart failure, renal failure, hyperaldosteronism, liver failure
excessive Na+ and water intake

Question 19

hypervolemia manifestations

Answer 19

increased ECF, edema, increased vascular volume
-ex: full, bounding pulse, pulmonary edema, shortness of breath, dyspnea (difficulty breathing), crackles+cough, venous distension (bulging)

Question 20

capillary fluid exchange

Answer 20

fluid filtered out of capillary into interstitium at arterial end>most fluid is reabsorbed at venous end>rest goes into lymphatics and returns to circulation
-hydrostatic pressure=PUSH
-COP=PULL

Question 21

edema

Answer 21

excessive fluid in interstitial space (ECF)
-increased COP “pull”
-decreased hydrostatic “push”
-increased capillarity permeability (proteins leak out, fluid drowns in)
-decreased or obstructive lymph flow
-localized or generalized
-pitting or non-pitting

Question 22

third-spacing

Answer 22

excess ECF fluid in body cavities
-ex: ascites (peritoneal), pleural effusion, pericardial effusion

Question 23

hypervolemia treatment

Answer 23

restrict fluid/Na+ intake
-serious: O2 therapy, morphine, intravenous diuretics, ventilation