Fluid Distribution and Movement Flashcards

1
Q

total body water

A

60% of total body weight in kg

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2
Q

what is fluid

A

water + solute

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3
Q

intracellular fluid

A

water inside of cells
- 2/3 of total body water
- separated by cell membrane from ECF
- regulated exchange

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4
Q

extracellular fluid

A

water outside of cells
- 1/3 of total body water
- interstitial, intravascular, and transcellular fluid

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5
Q

interstitial fluid

A

fluid within tissues
- 3/4 of ECFV
- separated by capillary endothelium from IVF

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6
Q

intravascular fluid

A

fluid within vessels
- 1/4 of ECFV

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7
Q

transcellular fluid

A

fluid within specialized compartments

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8
Q

does the ratio of fluid distribution in each compartment change at homeostasis

A

NO - constant ratios

does NOT depend on fluid volume

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9
Q

milliequivalence

A

content of a solute

mEq = millimoles x valence

1 mM CaCl2 =
- 1 mM Ca x 1 valence = 1 mM Ca
- 1 mM Cl2 x 2 valence = 2 mM Cl

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10
Q

does solute concentration OR ionic strength differ in each fluid compartment

A

solute concentration

compartments have the SAME ionic strength
different solute concentration allows for fluid flow

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10
Q

osmolarity

A

number of moles of solute per liter of solvent (mol/L)
- considers VOLUME

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11
Q

osmolality

A

number of moles of solute per kg of solvent (mol/kg)
- considers MASS

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12
Q

are osmolarity and osmolality equal in biology

A

YES - can be considered the same because 1 L of water = 1 kg of water

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13
Q

what is the osmolarity of plasma in healthy animals

A

300 mOsm/L

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14
Q

iso-osmotic

A

within 10% of 300 mOsm/L
(270-330 mOsm/L)

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15
Q

hyperosmotic

A

> 330 mOsm/L

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16
Q

hypo-osmotic

A

<270 mOsm/L

17
Q

osmotic pressure

A

the pressure needed to STOP osmosis (flow of water from high to low concentration)

18
Q

what does osmotic pressure depend on

A

NUMBER of molecules

19
Q

osmole

A

osmosis caused by a mole of a substance

1 mOsm = 1 mEq

20
Q

tonicity

A

effective osmolarity; creates osmotic gradients

ONLY measures effective osmoles

21
Q

effective osmoles

A

can NOT freely move across membranes
- exerts osmotic effects (causes water to move)
- excluded from ICFV

Na, Cl, proteins, glucose

22
Q

ineffective osmoles

A

can freely move across membranes
- does NOT exert osmotic effects (doesn’t cause water to move)

Urea, ethanol, lipid-soluble

23
Q

what type of solutes does osmolarity measure

A

effective AND ineffective solutes

24
what type of solutes does tonicity measure
effective osmoles ONLY
25
oncotic pressure
pressure exerted by proteins in plasma or interstitial fluid - pulls water INTO blood vessels mostly due to albumin
26
osmosis
water movement from area of high concentration to low - causes a change in volume in each compartment - equilibrates in 4 hrs regulated by Starling forces - hydrostatic and oncotic
27
blood volume
90 mL/kg in DOGS = IV fluid volume + red cell fluid volume
28
if PCV = 50% in a 20 kg dog, how can you solve for blood volume?
20 kg dog = 60% TBW = 12 kg water = 12 L water ECFV = 1/3 TBW = 4 L intravascular fluid = 1/4 ECFV = 1 L if PCV = 50%, then: 50% blood volume = IV fluid = 1 L 50% blood volume = red cells = 1 L blood volume = IV fluid + RBC = 2 L
29
how to assess IV fluid volume on exam
perfusion parameters: - mentation - MM color - CRT - pulse rate/quality - extremity temp.
30
hypovolemia
low IV fluid volume (hemorrhage or ECF lost through interstitial space) - pale MM - slow CRT - inc. pulse rate - dec. pulse quality - cold extremities
31
how to assess interstitial fluid volume
hydration parameters: - skin turgor - MM moist/dry - tear film production
32
dehydration
clinically detectable at 5% dehydrated (25% ECF loss) - dec. skin turgor - tacky MM - dec. tear film
33
where does fluid loss come from
interstitial fluid NOT hemorrhage
34
isotonic water loss
equal proportion of solute and water loss - no net water movement - intracellular water does NOT change - extracellular water loses water proportionally in IS/IV fluid compartments (3/4 water loss from IS, 1/4 water loss from IV) ex. diarrhea
34
hypertonic water loss
more solute loss than water loss - DECREASE osmolarity of interstitial fluid - water moves IS --> IV + IC - starling forces move water back from IV --> IS
35
hypotonic water loss
more water loss than solute loss - INCREASE osmolarity of interstitial fluid - water moves IV + IC --> IS hypernatremia - sign of hypotonic fluid loss ex. vomiting
36
pure water loss
caused by diabetes insipidus (excessive, unconcentrated urination) - INCREASE osmolarity of interstitial fluid hypernatremia
37
effects of hyperglycemia on water movement
high IV glucose causes water to move from ICFV --> ECFV causes hypervolemia + hyponatremia
38
effects of azotemia on water movement
high BUN does NOT cause water to move increases osmolarity w/o increasing volume in any compartment
39
effects of isotonic (0.9% NaCl) IV infusion
increases ECFV proportionally does NOT change ICF volume or osmolarity
40
effects of 5% dextrose IV infusion
mechanism of giving pure water IV without causing local area of hypo-osmolality increases all compartment volumes proportionally - small osmolarity decrease in all compartments