Body Fluid Compartments Flashcards

1
Q

Total body water (TBW)

  • Equation?
  • Normal value?
A

.6 x body weight

normal is 42 L

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2
Q

Total body water is divided up into?

A

-Extracellular fluid (ECF)
-Intracellular fluid (ICF)
divided by the cell membrane

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3
Q

Extracellular fluid (ECF)

  • Equation?
  • Normal value?
A

.2 x body weight

normal is 14 L

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4
Q

Intracellular fluid (ICF)

  • Equation?
  • Normal value?
A

.4 x body weight

Normal is 28 L

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5
Q

Extracellular fluid can be divided into?

A
  • Interstitial fluid

- Plasma

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6
Q

Interstitial fluid

  • Equation?
  • Normal value?
A

.75 x ECF

normal is 10.5 L

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7
Q

Plasma

  • Equation?
  • Normal value?
A

.25 x ECF

Normal is 3.5 L

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8
Q

What separates the interstitial fluid from the plasma?

A

Capillary wall

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9
Q

The plasma can be divided into?

A
  • Venous (compliance)

- Arterial

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10
Q

Venous

  • Equation?
  • Normal value?
A

.8 x plasma

-normal is 2.8 L

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11
Q

If blood volume is low, what happens to the blood that you do have?

A

It is shunted toward the more important organs (brain and kidneys) to protect them

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12
Q

Arterial

  • Equation?
  • Normal value?
A

.2 x plasma

Normal is .7 L

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13
Q

Arterial is also known as?

-What does this mean?

A

Effective Circulating Volume (ECV)

-Volume of arterial blood EFFECTIVELY PERFUSING TISSUE

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14
Q

Transcellular fluid

A
  • Also included in the ECF
  • It normally contains only a small amount of water such as epithelial secretions, synovial fluid, CSF, etc
  • It is said to occupy a “third space” (i.e. 3 ECF compartments)
  • Overabundance of fluid in third space can be pathologic
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15
Q
Hypovolemia due to vomiting
   -ECV?
   -ECF?
   -Plasma volume?
   -Cardiac output?
   -
A
  • ECV-decreased
  • ECF-decreased
  • Plasma volume-decreased
  • Cardiac output-decreased
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16
Q

Heart failure

  • ECV?
  • ECF?
  • Plasma volume?
  • Cardiac output?
A
  • ECV-decreased
  • ECF-increased
  • Plasma volume-increased
  • Cardiac output-decreased
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17
Q

Arteriovenous fistula

  • ECV?
  • ECF?
  • Plasma volume?
  • Cardiac output?
A
  • ECV-normal
  • ECF-increased
  • Plasma volume-increased
  • Cardiac output-increased
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18
Q

Severe Hepatic Cirrhosis

  • ECV?
  • ECF?
  • Plasma volume?
  • Cardiac output?
A
  • ECV-decreased
  • ECF-increased
  • Plasma volume-increased
  • Cardiac output-normal/increased
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19
Q

Clinical relevance of body fluid compartments

-Pharmacology-Volume of distribution (Vd) of a drug

A
  • Apparent volume of body fluid in which the total dose of the drug is distributed at the same concentration as in the plasma
  • Useful in calculating loading doses
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20
Q

If the Vd is less than or equal to 3L what compartment is the drug distributed in?

A

Drug is only in the plasma

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21
Q

If the Vd is 14L what compartment is the drug distributed in?

A

The drug is in the ECF (plasma and interstitial fluid)

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22
Q

If the Vd is 40-45L what compartment is the drug distributed in?

A

The drug occupies the total body water

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23
Q

If the Vd is is greater than 45L what compartment is the drug distributed in?

A

The drug is widely distributed and bound in body tissues

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24
Q

Normal daily urine output?

A

1400 mL

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25
Q

Donnan effect

A

Albumin is very large and negative so it attracts positively charged Na and K ions

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26
Q

Non-electrolytes

  • Protein levels in ICF and intravascular compartments?
  • Protein levels in interstitial fluid
A
  • Higher protein levels in ICF and intravascular compartments (primarily albumin)
  • Lower in interstitial fluid
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27
Q

Non-electrolytes

-Oncotic (osmotic?) pressure

A

Proteins normally do not move (membranes are impermeable to proteins), therefore they do not normally impact osmolarity but do exert oncotic pressure
-Osmotic pressure generated by large molecules (proteins) in solution which are impermeable to membranes

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28
Q

Volumes- indicator/dilution methods-slide 13

-Not sure if we need to know this

A

?

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29
Q

Balance of ions

-Normally, osmolarity is balanced between?

A
  • Interstitial and intravascular fluids (ECF compartments)

- ECF and ICF

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30
Q

Balance of ions

-Na and K concentration is slightly higher than expected due to?

A

Donnan effect

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31
Q

Osmolarity of body fluid compartments

-ECF osmolarity is due to?

A

[Na + Cl]

32
Q

Osmolarity of body fluid compartments

  • Concentration of Na in vasculature compared to interstitial fluid and ICF?
    • Due to?
A
  • Concentration of Na in vasculature > interstitial fluid > ICF…
    - Due to Na-K ATPase pump on cell membranes working normally
33
Q

Osmolarity of body fluid compartments

- Concentration of Na in vasculature > interstitial fluid > ICF...
    - Due to Na-K ATPase pump on cell membranes working normally
          - Disruption of pump activity by?
                - results in?
A

Disruption of pump activity by hypoxia results in increased ICF Na
-Water follows Na into cell and the cell swells

34
Q

Osmolarity of body fluid compartments

-ICF osmolarity is due to?

A

[K+]

35
Q

Osmolarity of body fluid compartments

-Plasma osmolality (osmolarity?) can be estimated by what two methods?

A

2 x [Na+]

2 x [Na+] + glucose/18 + urea/2.8

36
Q

Movement of water between compartments

  • Cell membrane between ECF and ICF
    • Permeable/impermeable to?
    • Fluid distribution between compartments is dependent on?
A
  • Highly permeable to water
  • NOT permeable to most electrolytes
  • Fluid distribution between two compartments is dependent on osmolar gradient
37
Q

Movement of water between compartments

  • Capillary membrane between ECF compartments is highly permeable to?
    • Fluid distribution is due to?
A
  • small ions

- Fluid distribution is due to a balance of Starling forces

38
Q

Movement of water between compartments

- Fluid distribution is due to a balance of Starling forces
     - which ones and which way do they go?
A
  • Capillary hydrostatic pressure (favoring filtration)

- Colloid oncotic pressure (primarily due to plasma proteins which opposes filtration)

39
Q

Fluid shifts-osmotic equilibrium

  • ECF osmolarity controls?
  • Water enters or leaves ECF rapidly in order to?
A
  • ECF osmolarity controls ICF volume

- Water enters or leaves ECF rapidly in order to balance osmolarity of ECF and ICF

40
Q

Fluid shifts-osmotic equilibrium

-Osmotic equilibration?

A

-Movement of water across cell membranes from higher to lower concentration as a result of an osmotic pressure difference (difference in number of solute particles in sol’n) across the membrane

41
Q

Fluid shifts-osmotic equilibrium

-Osmotic equilibration-osmotic pressure exerted across a membrane by a substance is also due to?

A

-osmotic pressure exerted across a membrane by a substance is also due to that membrane being impermeable to that solute

42
Q

Any fluid that enters your body goes through what fluid compartment FIRST?

A

Any fluid that enters your body goes through your ECF FIRST (acts as a reservoir)

43
Q

Darrow-Yannet Diagrams slide 20

A

?

44
Q

Fluid shifts

  • ICF and ECF
    - When does water move between them?
    - Equilibration of ICF and ECF osmolality occurs primarily by?
A
  • The ICF and ECF are in osmotic equilibrium
  • Water moves between these compartments only when an osmotic pressure gradient exists
  • Equilibration of ICF and ECF osmolality occurs primarily by shifts in water (not shifts in solute)
45
Q

Factors affecting osmolarity and volume of ECF and ICF

A
  • water ingestion/dehydration
  • intravenous infusions
  • diarrhea/vomiting
  • sweating
  • diuresis
  • disease
46
Q

Examples

  • Excessive NaCl intake, hyperaldosteronism (Conn’s disease)
    - ECF volume?
    - ICF volume?
    - ECF mOsm?
    - ICF mOsm?
A
  • ECF volume-increased
  • ICF volume-decreased
  • ECF mOsm-increased
  • ICF mOsm-increased
47
Q

Examples

  • Water gain (SIADH, psychogenic polydypsia)
    - ECF volume?
    - ICF volume?
    - ECF mOsm?
    - ICF mOsm?
A
  • ECF volume-increased
  • ICF volume-increased
  • ECF mOsm-decreased
  • ICF mOsm-decreased
48
Q

Examples

  • Water loss (dehydration)
    - ECF volume?
    - ICF volume?
    - ECF mOsm?
    - ICF mOsm?
A
  • ECF volume-decreased
  • ICF volume-decreased
  • ECF mOsm-increased
  • ICF mOsm-increased
49
Q

Examples

  • NaCl loss
    - ECF volume?
    - ICF volume?
    - ECF mOsm?
    - ICF mOsm?
A
  • ECF volume-decreased
  • ICF volume-increased
  • ECF mOsm-decreased
  • ICF mOsm-decreased
50
Q

Many diseases are accompanied by fluid shifts between compartments
-Important for treatment?

A

Maintenance of adequate fluids in ICF, ECF or both is important in treatment of these patients

51
Q

Fluid distribution between plasma and interstitial fluid (within ECF) is maintained by?

A

balance of hydrostatic and osmotic forces across capillaries

52
Q

Fluid distribution between ECF and ICF is determined by?

A

osmotic effect of small solutes across cell membrane (highly water permeable, but impermeable to ions)

53
Q

Clinical relevance of fluid balance-hydration therapy/replacement fluids
-Intravenous replacement fluids used when oral rehydration not suitable-Targets compartment which is volume-depleted

A

K

54
Q

Clinical relevance of fluid balance-hydration therapy/replacement fluids

- Distribution in compartments depends on type of fluid
      - 2 types?
A
  • Crystalloid fluids

- Colloid fluids

55
Q

Crystalloid fluids

A
  • Contain varying concentrations of electrolytes

- Can stay in ECF or be widely distributed depending on composition (e.g. normal saline, lactated Ringer’s solution)

56
Q

Colloid fluids

A

Contain large proteins and molecules which tend to stay within the vascular space (e.g. dextran, albumin)

57
Q

Other important terms-isosmotic, hyperosmotic, hyposmotic solutions
-What do these terms indicate?

A

Indicates osmolarity of solution compared to ECF (these terms do NOT indicate whether the cell membrane is permeable to the solute)

58
Q

Isomotic

A
  • Solutions which have the same osmolarity as the ECF

- When added to the ECF, does not change osmolarity, increases volume ONLY

59
Q

Hyperosmotic

A
  • Solution has an osmolarity greater than that of the ECF
  • When added to the ECF, osmolarity increases and causes water to flow out of the cells to the ECF compartment with a resulting increase in ECF volume and decrease in ICF volume
60
Q

Hyposmotic

A
  • Solution has an osmolarity less than that of the ECF
  • When added to the ECF, decreases osmolarity and water moves into the cells to equalize osmolarity
  • ECF and ICF volumes are both increased
61
Q

Tonicity

A

-Changes in cell volume due to osmotic equilibrium with water movement across cell membranes

62
Q

Tonicity

-Small changes in concentration of impermeant solutes in ECF can cause?

A

large changes in cell volume

63
Q

Tonicity

-Movement of water?

A

Water always moves from an area in which it is in higher concentration to an area of lower concentration

64
Q

Isotonic solution

A

No change is cell volume

65
Q

Hypotonic solution

A

cell swells

66
Q

Hypertonic solution

A

Cell shrinks

67
Q

Fluid exchange/balance

-Distribution of fluid between the ECF and ICF compartments is determined primarily by?

A
  • Ion distribution (Na)

- ATPase activity (keeps Na(inside) low and K(inside) high)

68
Q

Fluid exchange/balance

-Distribution of ECF between the plasma and interstitial compartments is determined primarily by?

A
  • Balance of hydrostatic vs. oncotic pressures

- intravascular pressure in capillaries vs. plasma protein and solute concentration

69
Q

Edema

-Palpable swelling produced by expansion of?

A

Interstitial fluid volume

70
Q

Edema

-Palpable swelling produced by expansion of interstitial fluid volume-Caused by?

A
  • Alteration in capillary hemodynamics (altered Starling forces with increased net filtration pressure)-fluid moves from vascular space into the interstitium
  • Renal retention of dietary Na and water-expansion of ECF volume
71
Q

Edema

  • Altered Starling forces-renal role
    • When does edema become apparent? Therefore?
A
  • Edema does not become apparent until interstitial volume is increased by 2.5-3L (normal plasma volume is only 3L)
  • Therefore, edema fluid is not derived only from plasma
  • Compensatory renal retention of Na and water to maintain plasma volume in response to underfilling of the vasculature must occur in this situation to cause edema
72
Q

Edema

-This renal compensation is?

A

This renal compensation is appropriate to restore tissue perfusion although it exacerbates edema
-e.g. CHF

73
Q

Edema

-Renal retention of Na and water-results in?

A
  • Overfilling of the vascular tree
  • Inappropriate renal fluid retention
  • Usually results in elevated blood pressure, expanded plasma and interstitial volumes
  • E.g. primary renal disease (glomerulonephritis, nephrotic syndrome)
74
Q

Non-pitting edema

A

Swollen cells due to increased ICF volume

75
Q

Pitting edema

A

Increased interstitial fluid volume

76
Q

Edema often treated with?

A

diurectics