9) Body water and electrolytes Flashcards

1
Q

list main body cations

A

sodium
potassium
calcium
magnesium
trace elements

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2
Q

list main body anions

A

chloride
bicarbonate
proteins (albumin)
organic acids (lactate)
sulfate
phosphate

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3
Q

main intracellular ions

A

K+
phosphate
proteins

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4
Q

main extracellular ions

A

Na+
Cl-
HCO3-
proteins

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5
Q

Na+ functions

A

Maintains osmolality

Regulates acid-base balance by Na-H exchange in kidneys

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6
Q

K+ functions

A

Involved in heart and skeletal muscle contraction
Maintains intracellular osmolality
Influences acid-base balance

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7
Q

80% plasma osmolality is due to…

A

Na and Cl

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8
Q

chloride functions

A

Maintains plasma osmolality with sodium
Chloride shift (Maintains electroneutrality when Cl- exchanges with HCO3-)

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9
Q

Test used to diagnose children with Cystic Fibrosis

A

sweat chloride

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10
Q

> 60 mmol/L chloride is positive for…

A

CF

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11
Q

———- and the agent ——– is used to stimulate sweat production on the skin of a child

A

Iontophoresis
pilocarpine

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12
Q

how does hemolysis affect electrolyte measures?

A

Increased Potassium
Increased Phosphorus
Increased Iron
Increased Magnesium
Increased AST, ALT, CK, Troponin, and LD (liver & cardiac enzymes)

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13
Q

calculate anion gap

A

AG = [Na + K] - [Cl + HCO3]

or

AG = AG = Na - [Cl + HCO3]

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14
Q

causes of increased AG (not mudpiles)

A
  • Renal Tubular Disease
  • Diabetic Ketoacidosis
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15
Q

causes of low AG

A
  • low albumin (most common)
  • Organic paraproteins
  • Inorganic bromide, lithium, Iodine, or Polymyxin B
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16
Q

MUDPILES

causes of high AG

A
  • methanol
  • uremia
  • DM
  • paraldehyde
  • isoniazid
  • lactic acidosis
  • ethylene glycol/ethanol
  • salicylate
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17
Q

major difference between plasma and ISF

A

presence of protein in plasma and virtually none in ISF

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18
Q

Represents a heterogeneous mixture of solutes that are difficult to measure directly because of the lack of cells free of contamination

A

intracellular water compartment

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19
Q

interactions of physical forces within and among fluid compartments

A

Gibbs-Donnan equilibrium

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20
Q

Used to identify the number of moles of a particle per kilogram of water, not the kind of particle

A

osmolality

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21
Q

Solution concentrations expressed on a weight factor are ——— independent

A

temperature

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22
Q

As osmolality increases…
- Osmotic pressure
- Boiling point
- Freezing point
- Vapor pressure

A

increases
increases
decreases
decreases

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23
Q

explain how the freezing point osmometer works

A
  • Sample is rapidly supercooled to several degrees below its freezing point.
  • Then agitated with the stirrer to initiate freezing.
  • Rate at which this heat of fusion is released from the ice being rapidly formed reaches equilibrium with the rate of heat removed.
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24
Q

The freezing point is lowered by an amount that is directly proportional to…

A

the concentration of dissolved particles in the solution

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25
Q

osmolality equation

A

mOsm/kg = (1.86)(Na) + (Glucose/18) + (BUN/2.8) + 9

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26
Q

osmol gap

A

osmol gap = measured osm - calculated osm

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27
Q

the causes of high osmol gap and AG are basically the same, except…

A

salicylate poisoning does not cause high osmol gap

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28
Q

Pressure created in a solution by the presence of large (> 30 kDa) proteins, also called colloids.

A

colloid oncotic pressure

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29
Q

hypothalamus responds to these stimuli in order to regulate water balance

A

Increases in extracellular water osmolarity
Decreases in intravascular volume
Angiotensin II

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30
Q

angiotensin II effect on transport

A

increases NaCl and H2O reabsorption

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31
Q

aldosterone effect on transpoart

A

increases NaCl and H2O reabsorption

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32
Q

ANP, BNP, CNP effect on transport

A

inhibits NaCl and H2O reabsorption

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33
Q

urodilantin effect on transport

A

inhibits NaCl and H2O reabsorption

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34
Q

ADH effect on transport

A

Increases H2O reabsorption

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35
Q

Causes increased thirst and water intake

A

thirst center

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36
Q

Stimulates the posterior pituitary gland to secrete Antidiuretic Hormone (ADH)

A

antidiuretic center

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37
Q

2 areas of hypothalamus responding to low water

A

thirst center (water intake)
antidiuretic center (water output)

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38
Q

RAAS regulates…

A

Body sodium and water content
Arterial blood pressure
Potassium balance

39
Q

proteolytic enzyme produced, stored, and secreted by juxtaglomerular cells of the kidneys

A

renin

40
Q

angiotensin II functions

A
  • Stimulation of aldosterone secretion by the adrenal cortex
  • Arteriolar vasoconstriction, which increases blood pressure
  • Stimulation of ADH secretion and thirst
  • Enhancement of NaCl reabsorption by the proximal tubule
41
Q

aldosterone functions

A
  • Na+ reabsorption in the distal nephron of the kidneys
  • Water reabsorption in the kidneys
  • K+ excretion (secretion) by the kidneys
42
Q

Low effective circulating blood volume can be sensed by baroreceptors located in the…

A

carotid sinus and aortic arch

43
Q

3 natriuretic peptides

A

Atrial (A)-type natriuretic peptide (ANP)
Brain (B)-type natriuretic peptide (BNP)
(C)-type natriuretic peptide (CNP)

44
Q

natriuretic peptides respond to…

A

intravascular volume expansion

45
Q

Hormone produced primarily in atria

A

ANP

46
Q

ANP functions

A
  • Reducing the venous pressure that occurs with a given increase in blood volume
  • Increasing vascular permeability
  • Promoting natriuresis and diuresis
47
Q

natriuresis

A

excretion of Na+ in urine

48
Q

Hormone produced and stored in cardiac ventricles

A

BNP

49
Q

Levels increase in Congestive Heart Failure

A

BNP

50
Q

Produced in vascular endothelial cells, brain, and renal tubules

A

CNP

51
Q

Potent venous dilator, but no natriuretic effect

A

CNP

52
Q

In the brain, ANP inhibits….

A

salt appetite
water intake
secretion of ADH and corticotropin

53
Q

conditions associated with dilutional hyponatremia

A

Weight gain & excess edema
Liver failure
Congestive heart failure
Renal failure
Nephrotic syndrome
Inappropriate ADH secretion

54
Q

hyponatremia causes

A

v/d
polyuria

55
Q

hypernatremia causes

A

Ingestion of large amounts of sodium salts
Administration of hypertonic NaCl Hyperaldosteronism
Excessive sweating
DI
Osmotic diuresis

56
Q

Small amount is taken up by cells and most excreted by the kidneys

A

K+

57
Q

hyperkalemia s/s

A

Mental confusion
Weakness
Tingling sensations
Flaccid paralysis of the extremities
Respiratory muscle weakness

58
Q

causes of pseudohyperkalemia

A

Hemolysis
Leukocytosis
Vigorous arm exercise
Tight application of tourniquet
Squeezing the area around a draw site

59
Q

causes of hyperkalemia

A

High-potassium uptake
Decreased K+ excretion
Crush injuries
Digitals overdose
Tissue hypoxia
Metabolic acidosis

60
Q

causes of hypokalemia

A

Metabolic alkalosis
Diuretic administration
Increased GI loss
Increased urinary loss

61
Q

Metabolic ——– is often associated with hyperkalemia because potassium moves out of the cell and into the extracellular water space.

A

acidosis

62
Q

Metabolic ——- is a condition characterized by hypokalemia. Potassium ions move from the extracellular water space and into the cell.

A

alkalosis

63
Q

causes of hyperchloremia

A

Dehydration
Kidney diseases
Salicylate intoxication

64
Q

causes of hypochloremia

A

Vomiting
Salt-losing nephritis
Metabolic acidosis

65
Q

Decreased secretion of Cortisol and Aldosterone

Causes water and Na loss by kidneys

A

Addison’s disease

66
Q

diuretics used to tx…

A

conditions that have fluid retention (also called edema) as a symptom, such as heart failure, kidney failure and cirrhosis of the liver

67
Q

Characterized by polyuria accompanied by polydipsia because of ADH deficiency

A

DI

68
Q

central vs nephrogenic DI

A

Central DI is caused by a failure of the pituitary gland to secrete normal amounts of A D H in response to osmoregulatory factors.

Nephrogenic DI patients have renal resistance to the action of ADH. Still producing ADH, but just not receptive to it.

69
Q

DI s/s

A

Increased urine output >2.5L/day
Low urine specific gravity, low urine osmolality
Crave water/ice
Extreme fatigue, muscle pain/weakness
Increased serum osmolality, hypernatremia

70
Q

causes of DI

A
  • Kidneys not receptive to ADH
  • Damage to the pituitary gland and/or hypothalamus
  • Brain trauma through stroke or head trauma
  • Tumors
  • Drugs (demenocycline)
  • Gestational due to the placenta producing vasopressinase
71
Q

parts of DI dx

A

polyuria
urine glucose testing to exclude glycosuria
measurement of urine and serum creatinine, electrolytes, and osmolality
A water-deprivation test is useful to distinguish central from nephrogenic DI

72
Q

water deprivation test is d/c if…

A

urine osmolality rises above 500 or if the patient loses more than 3% of body weight, without a rise in urine osmolality

73
Q

goal of DI therapy

A

urine osmolality up
urine output down

74
Q

A chronic, excessive intake of water suppresses ADH secretion and produces hypotonic polyuria

A

Psychogenic or Primary Polydipsia

75
Q

The increased production of ADH in the absence of known stimuli for its release

A

syndrome of inappropriate ADH secretion

76
Q

SIADH s/s

A

Low serum osmolality
Normal to increased plasma volume
Fluid overload (weight gain)
Hypotonic (low osmotic pressure) plasma and urine
Hyponatremia, with continued sodium excretion
Low urine output with high specific gravity and increased urine osmolality

77
Q

—— is suspected if urine osmo > plasma osmo without corresponding low urine Na

A

SIADH

78
Q

tx for moderate SIADH

A

Loop Diuretics (Lasix)
Hypertonic IV solutions (3% Saline)

79
Q

tx for severe SIADH

A

Demeclocycline

80
Q

water overload —ADH, water, serum osmo, serum Na, urine output, urine osmo

A

ADH—
water ↑
serum osmo ↓
serum Na ↓
urine output ↑
urine osmo ↓

81
Q

DI — ADH, water, serum osmo, serum Na, urine output, urine osmo

A

ADH↓
water ↓
serum osmo ↑
serum Na ↑
urine output ↑
urine osmo ↓

82
Q

SIADH —ADH, water, serum osmo, serum Na, urine output, urine osmo

A

ADH↑
water ↑
serum osmo ↓
serum Na ↓
urine output ↓
urine osmo ↑

83
Q

suspect ingestion if osmo gap…

A

> 25

84
Q

causes of high osmo gap without high AG

A
  • isopropyl alcohol
  • mannitol
  • sorbitol
  • glycine
  • maltose
85
Q

cannot be used as an anticoag for electrolyte specimens

A

sodium heparin

86
Q

Lipemic samples can interfere with…

Sodium falsely decreased due to…

A

indirect ISE measurement
electrolyte exclusion effect

87
Q

ISE

A

ion-selective electrode

88
Q

direct vs indirect ISE

A

direct —no dilution
indirect —sample diluted

89
Q

electrolyte instruments account for —% solid portion of plasma

A

7%

90
Q

4 methods of measuring Na+

A

Both direct and indirect ISEs
Flame-emission spectroscopy (obsolete)
Atomic-absorption spectroscopy
Spectrophotometry

91
Q

extra K+ in serum (compared to plasma) is mainly a result of…

A

platelet rupture during coagulation

0.1-0.7 mEq/L lower

92
Q

Slight hemolysis can raise K+ vales —-%, marked hemolysis —%, and gross hemolysis —–%

A

3
12
30

93
Q

incorporates valinomycin into its organic liquid membrane

A

ISE for K+

94
Q

Macroduct coils

A

used to collect sweat