LMP301 Lecture 3: Fluid Balance Flashcards

0
Q

How much ICF is there?

A

28L

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1
Q

ECF can be subdivided into…

A
  • Plasma

- Interstitial fluid (ISF)

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2
Q

How much ECF is there?

A

14L

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3
Q

How much plasma is there?

A

3.5L

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4
Q

How much ISF is there?

A

10.5L

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5
Q

ACE inhibitor = ?

A

angiotensin converting enzyme inhibitor

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6
Q

What are ACE inhibitors used for and how do they work?

A

Used for hypertension

Work by dilating blood vessels

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7
Q

What are the common electrolytes measured?

A
Na+
K+
Bicarbonate
Ca++
Potassium phosphate
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8
Q

Where are electrolytes measured from?

A

Plasma

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9
Q

Plasma and electrolytes are most abundant in…

A

ICF

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10
Q

Is it harder to do ECF or ICF measurement?

A

ICF

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11
Q

What are extracellular ions?

A

Na+
Cl-
HCO3-
Ca++

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12
Q

What are intracellular ions?

A

K+
PO4
Anions

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13
Q

Define: concentration

A

amount of solute in a solvent

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14
Q

Define: osmolality

A

amount of solute particles in a solvent (weight)

mmol/kg
mOsm/kg

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15
Q

How to estimate osmolality?

A

Measure the most abundant solutes:

2[Na+] & [Glucose] & [Urea]

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16
Q

Define: osmolarity

A

amount of solute particles in 1kg of water (WATER IS SOLVENT)

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17
Q

When measuring dilute aqueous solutions, the appropriate unit is…concentration / osmolality / osmolarity

A

osmolarity

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18
Q

One weakness of concentration measurements

A

Must take into account total volume of solvent (dehydrated might affect measurement of electrolytes)

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19
Q

Osmolarity is a passive / active process?

A

passive

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20
Q

Define: oncotic pressure

A

Pressure in the capillaries

Walls of capillaries act as semi-permeable membrane, and proteins pull water into plasma.

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21
Q

Define: hydrostatic pressure

A

Pressure exerted by the heart when it pumps

Pushes fluid in vessels into ISF.

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22
Q

Oncotic pressure is balanced by…

A

Hydrostatic pressure

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23
Q

Hydrostatic pressure is balanced by…

A

Oncotic pressure

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24
Q

What might affect oncotic pressure?

A
  • Injury: cause proteins in plasma to leak out
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25
Q

Typical input of water?

A

0.5 - 5L per day

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26
Q

Amount of output of water through renal processes?

A

0.5 - 4L per day

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27
Q

Amount of output of water through GI tract?

A

< 0.1 L per day

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28
Q

Amount of output of water through insensible loss?

A

0.5 - 1L per day

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29
Q

Define: insensible loss

A

Loss of fluid through sweat & respiration

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30
Q

Most of body fluids are lost through…

A

Renal processes (kidney)

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31
Q

Define: dehydration

A

Releasing more fluid than you’re consuming

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32
Q

Define: overhydration

A

Taking in more fluid than you’re releasing

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33
Q

Define: polyuria

A

A lot of pee

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34
Q

Define: polydipsia

A

Consuming a lot of water

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35
Q

Define: oligouria

A

Small amount of urine output

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36
Q

Define: anuria

A

no urine output

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37
Q

What medical term falls under dehydration?

A

polyuria

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38
Q

What medical terms fall under overhydration?

A
  • polydipsia
  • oligouria
  • anuria
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39
Q

Features of dehydration (physical)

A
  • increased pulse
  • dry mucous membranes
  • soft / sunken eyeballs
  • decrease bld pressure
  • decreased urine
  • decreased skin turgor
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40
Q

Biochemical signs of dehydration

A
  • increased plasma sodium
  • increased bld urea
  • increased hematocrit
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41
Q

Define: hematocrit

A

volume of RBC in blood

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42
Q

What is edema?

A

Accumulation of fluid in the ISF of your cells

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43
Q

Edema is a symptom of…

A

overhydration

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44
Q

Features of overhydration (physical)

A
  • normal pulse
  • normal mucous memb
  • normal eyeballs
  • normal / incr bld pressure
  • normal / decr urine
  • incr skin turgor
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45
Q

Symptoms of overhydration (biochem)?

A
  • normal / decr plasma sodium
  • normal / decr bld urea
  • normal / decr hematocrit
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46
Q

How is water regulated in the body?

A
  1. Control osmolality

2. Control bld volume

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47
Q

Which is the direct route of water regulation?

A

control of osmolality

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48
Q

which is the indirect route of water regulation?

A

control of bld volume

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49
Q

How is osmolality controlled in the body? (via ADH)

A
  1. Hypothalamus senses bld osmolality
  2. Hypothalamus tells p. pituitary to make ADH
  3. ADH goes to kidney collecting tubules
  4. Kidney absorbs more water
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50
Q

more Na+ in the bld indicates… (in terms of osmolality)

A

higher bld osmolality

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51
Q

Less Na+ in the bld indicates ____ osmolality

A

lower

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52
Q

How is osmolality controlled in the body?

A
  1. ADH

2. Thirst

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53
Q

How is osmolality controlled in the body? (Thirst)

A
  1. Hypothalamus tells you to drink water

2. When homeostasis is reached, hypothalamus tells p. pituitary to stop secreting ADH

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54
Q

SIADH

A

syndrome of inappropriate ADH secretion

55
Q

What does SIADH do?

A

Secrete too much ADH

Too much water reabsorbed

56
Q

DI

A

Diabetes Insipidus

57
Q

What is the symptoms of DI?

A

Not enough ADH secreted

Water not reabsorbed-> dehydration

58
Q

How is sodium stored in the body?

A

25% in bones / tissues

75% in ECF

59
Q

How is sodium regulated?

A
  1. Aldosterone

2. ANP

60
Q

Aldosterone is secreted by…

A

adrenal gland

61
Q

Aldosterone is secreted in response to…

A

ATII (angiotensin II)

62
Q

What does aldosterone cause?

A

Na+ resorption in kidney (but H+ and K+ secreted as a result)

63
Q

ANP

A

atrial naturetic peptide

64
Q

ANP is secreted by…

A

atria of heart

65
Q

What stimulates ANP secretion?

A

Amount of stretch of tissues in the heart (incr. stretch stimulates release)

66
Q

ANP causes…

A

Na+ secretion in kidney (also get rid of water because it carries the Na+)

67
Q

How is bld volume controlled?

A
  1. Renin (from kidney) converts angiotensinogen -> ATI
  2. ACE converts ATI -> ATII
  3. ATII causes vasoconstriction, Na+ resorption in kidney, aldosterone release
  4. Aldosterone stimulate Na resorption
68
Q

What is renin?

A

enzyme secreted by kidney

69
Q

What stimulates renin secretion?

A

low blood pressure

70
Q

What converts ATI -> ATII?

A

ACE (angiotensin converting enzyme)

71
Q

Aldosterone increases plasma Na+ at the expense of…

A

K+

72
Q

What are the effects of aldosterone on K+?

A
  • Decrease bld K+

- Increase urine K+

73
Q

What is the effect of aldosterone on Na+?

A
  • Increase bld Na+

- Decr. urine Na+

74
Q

Define: hypernatremia

A

Increased serum [Na+]

75
Q

What is the value for hypernatremia?

A

> 145 mmol/L

76
Q

What are some causes of hypernatremia?

A
  1. Decr. body water
  2. Water loss > Na+ loss (hypotonic)
  3. Excess Na+ intake
77
Q

What causes decreased body water?

A
  1. Decreased water intake

2. Excess water loss (DI)

78
Q

What causes water loss > Na+ loss?

A

.

79
Q

What is osmotic diuresis?

A

Things that draw water out along with it

e.g. excretion of glucose in urine will cause water to also be excreted

80
Q

What causes excess Na+ intake?

A
  1. Diet
  2. IV
  3. Hyperaldosteronism (Conn’s syndrome, Cushing’s syndrome)
81
Q

Conn’s syndrome

A

too much aldosterone

82
Q

Cushing’s syndrome

A

Too much cortisol

act like aldosterone in terms of Na+ reabsorption

83
Q

What is hyponatremia?

A

Low serum [Na+]

84
Q

What causes hyponatremia?

A
  1. Increased water in body
  2. Na+ loss > water loss (hypertonic urine)
  3. Decreased Na+ in body
85
Q

What causes increased water in body?

A
  1. excess water intake
  2. SIADH
  3. Renal failure
  4. Edema (nephrotic syndrome, heart failure)
  5. IV
86
Q

2 things that cause edema

A
  1. Nephrotic syndrome

2. Heart failure

87
Q

What is nephrotic syndrome?

A

Non-specific kidney disease

???

88
Q

What causes Na+ loss > water loss in urine?

A
  1. Diarrhea
  2. Sweating
  3. Burns
  4. Diuretics
89
Q

What causes decreased body Na+?

A
  1. Adrenal insufficiency / not enough aldosterone (Addison’s disease)
90
Q

Addison’s disease

A

Too little aldosterone

91
Q

Which symptom of hyponatremia & hypernatremia is the same?

A

Na+ loss > or < than water loss

Sweating, diarrhea

92
Q

What happens if the kidney can’t respond to aldosterone?

A

Problems with Na+ reabsorption

93
Q

What does kidney disease cause?

A

Kidney can’t respond to aldosterone

94
Q

What does diuresis cause?

A

kidney secreting more Na+ / secreting more Na+ and K+

-> diuretics

95
Q

What is the effect of adrenal disease?

A

Too much / little production of aldosterone

96
Q

ADH and aldosterone have the [same / different] effects in terms of Na+?

A

Same

97
Q

How does the body respond to edema?

A
  1. Release aldosterone

2. Release ADH

98
Q

Edema causes a ___ in effective circulating volume

A

decrease

99
Q

Things that may cause edema:

A
  1. heart failure

2. hypoalbuminemia

100
Q

How does heart failure contribute to edema?

A

Fluid in vessels accumulate instead of pumped by the heart-> goes into ISF

101
Q

How does hypoalbuminemia contribute to edema?

A

Less albumin -> less oncotic pressure -> more fluid in ISF

102
Q

How to examine Na+ disorders?

A
  1. Examine serum [Na+] (hypo / hypernatremia)
  2. Examine bld volume (de / overhydrated)
  3. Examine input / output of water & Na+
  4. Consider organ dysfunction (kidney, p. pituitary, adrenal gland)
103
Q

Aldosterone is secreted by…

A

adrenal gland

104
Q

IV

A

Intravenous Fluid Therapy

105
Q

What is IV used for?

A

correct imbalances in the body

106
Q

IV can contain…

A
  1. 5% dextrose
  2. 0.9% saline (NaCl)
  3. Plasma
107
Q

Dextrose in IV

A
  • Correct overall dehydration (ECF & ICF)

- Isotonic w/ plasma, glucose quickly metabolized so only water remains

108
Q

Why can’t water be directly given as IV to rehydrate someone?

A

Water is very hypotonic, and will cause cells to explode

109
Q

Saline (NaCl) in IV

A
  • For dehydration in ECF

- Isotonic to plasma

110
Q

Plasma in IV

A
  • Correct dehydration in vessels (vascular compartment)
  • Given by donor
  • Contains electrolytes & protein
  • Protein -> oncotic pressure -> more water in vessels
111
Q

Role of potassium?

A
  1. Maintain membrane potential
  2. Heart beat & contraction
  3. Acid-base balance
112
Q

What role does K+ play in acidosis?

A
  1. H+ may get in cells
  2. K+ has same charge-> pushed out of cells int vessels
  3. High K+ in bld = hyperkalemia
113
Q

Severe kyperkalemia causes…

A

Irregular heart beat

Death

114
Q

How is K+ stored?

A

99% in ICF

1-2% in ECF

115
Q

Main loss of K+?

A

Renal

116
Q

What causes hyperkalemia?

A
  1. Acidosis
  2. Cells break
  3. Excess intake
  4. Renal failure
  5. Mineralocorticoid deficiency
117
Q

What is the cutoff for hyperkalemia?

A

> 6 mmol/L

118
Q

How does mineraldocorticoid deficiency lead to hyperkalemia?

A
  1. Adrenal gland doesn’t produce aldosterone

2. Drugs that inhibit aldosterone production

119
Q

What is the cutoff for hyponatremia?

A

< 135 mmol/L

120
Q

What is the cutoff for hypokalemia?

A

< 3 mmol/L

121
Q

What causes hypokalemia?

A
  1. alkalosis
  2. renal loss
  3. drugs
  4. gastrointestinal loss (diarrhea & vomiting)
122
Q

Define: alkalosis

A

Bld pH is basic

123
Q

How does alkalosis affect K+?

A

K+ goes into cells -> hypokalemia

124
Q

[More / less] aldosterone causes hypokalemia

A

More

125
Q

What drugs causes hypokalemia?

A

Thiazide diuretics

Corticosteroids

126
Q

What does thiazide diuretics do?

A

Excrete Na+ and K+

127
Q

What is pseudohyperkalemia?

A

Falsely high plasma K+

128
Q

What leads to pseudohyperkalemia?

A
  1. Hemolysis during venipuncture
  2. Too long tourniquet
  3. Disease (too much WBC, platelets)
129
Q

What is released during clotting?

A

K+

130
Q

What is tourniquet?

A

Tying off the arm when getting a shot

131
Q

What is venipuncture?

A

getting a shot

132
Q

Renin and aldosterone are sensitive to ____

A

Posture

133
Q

What is something you have to make sure when doing a recumbent sample?

A

Compare with the right range (recumbent range)

134
Q

Recumbent

A

Sample lying down