fluid, electrolyte, and acid-base balance (ch 25) Flashcards

1
Q

body water content

A

babies - 75%
females - 50%
males - 60%
elderly - <50%

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2
Q

fluid compartments

A

intracellular fluid (ICF) compartment - 2/3 body H2O
extracellular fluid (ECF) compartment - 1/3 body H2O

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3
Q

components of ECF

A

20% plasma, 80% interstitial fluid

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4
Q

nonelectrolytes

A

most are organic, not ions

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5
Q

nonelectrolyte examples

A

glucose, small amounts of proteins/lipids
inorganic - urea + creatinine

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6
Q

electrolytes

A

molecules that dissociate into ions in water to conduct electrical current

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7
Q

electrolyte examples

A

salts, acids/bases, some proteins

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8
Q

electrolytes in ECF

A

major cation: Na+
major anion: Cl-
(except plasma - higher protein, lower Cl-)

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9
Q

electrolytes in ICF

A

major cation: K+
major anion: phosphate
(more soluble proteins than in plasma)

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10
Q

largest mass of dissolved solutes

A

proteins

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11
Q

osmolarity

A

solutes/volume of H2O

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12
Q

osmolality

A

solutes/mass of solvent

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13
Q

characteristics of fluid movement among compartments

A

water moves freely along osmotic gradients
body fluid osmolality almost always equal

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14
Q

how do changes in solute concentration affect water flow

A

increase in ECF osmolality –> water leaves cells
decrease in ECF osmolality –> water enters cells

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15
Q

types of fluid movement

A

between plasma and IF across capillary walls
between IF and ICF across cell membranes

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16
Q

how do ions move

A

selectively through concentration gradients

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17
Q

water balance

A

water intake must equal water output

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18
Q

distribution of water intake (greatest to least)

A

beverages>food>metabolism

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19
Q

distribution of water output (greatest to least)

A

urine>insensitive losses (skin and lungs)>sweat>feces

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20
Q

how is body fluid osmolality maintained

A

rise (decrease in body H2O): increase in ADH and thirst
fall (increase in body H2O): decrease in thirst and ADH

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21
Q

fluid intake is governed by the ______

A

hypothalamic thirst center

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22
Q

hypothalamic osmoreceptors detect ______

A

ECF osmolality

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23
Q

inputs to stimulate thirst

A

increase in plasma osmolality
dry mouth
low blood volume/BP
angiotensin II or baroreceptor input to stimulate thirst

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24
Q

what inhibits thirst

A

relief of dry mouth
activation of stomach and intestinal stretch receptors

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25
Q

how does ADH influence water output

A

an increase in body osmolality stimulates ADH, decreasing urine output

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26
Q

disorders of water balance

A

dehydration
water intoxication
edema

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27
Q

dehydration causes

A

increased sweat
decrease fluid to drink
vomiting
diarrhea
diuretic medication
alcohol
burns

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28
Q

signs and symptoms of dehydration

A

thirst
dry mouth
decreased urine output
dry skin

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29
Q

results of dehydration

A

weight loss –> decreased BP –> confusion –> hypovolemic shock

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30
Q

causes of water intoxication

A

renal insufficiency
rapid excess water ingestion

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31
Q

results of water intoxication

A

decrease in ECF osmolality –> hyponatremia –> osmosis of H2O into body cells –> swelling of cells –> cerebral swelling –> headache –> death

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32
Q

treatment of water intoxication

A

hypertonic saline solution via IV

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33
Q

what is edema

A

too much interstitial fluid, leading to tissue (not cell) swelling from fluid coming out of the blood into the ICF

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34
Q

causes of edema

A

increased capillary hydrostatic pressure or permeability
low blood proteins
blocked (or surgically removed) lymphatic vessels

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35
Q

central role of sodium

A

controls ECF volume and water distribution - therefore determines BP

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36
Q

which movement mechanisms are coupled to the sodium ion

A

gradients, glucose, amino acids

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37
Q

how is sodium balance regulated

A

no known receptors, so Na+ levels in blood fluids is linked to blood pressure and volume

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38
Q

how is sodium mainly reabsorbed

A

by the kidney/PCT

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39
Q

aldosterone causes

A

reabsorption of Na+ in the DCT and collecting ducts
increased K+ secretion into urine

40
Q

main trigger for aldosterone release

A

angiotensin II via the renin angiotensin system

41
Q

alternative trigger for aldosterone release

A

elevated levels of K+

42
Q

how long for aldosterone to take effect

A

slowly - hours to days

43
Q

atrial natriuretic peptide is released by

A

atrial cells in response to stretch in the atria (which increases BP and venous return)

44
Q

function of ANP

A

decreases hormones (ADH, renin/angiotensin II, aldosterone)
increases excretion of Na+ and H2O in urine, decreasing BP

45
Q

estrogens act like

A

aldosterone

46
Q

progesterone blocks

A

aldosterone

47
Q

function of glucocorticoids

A

increase Na+ reabsorption

48
Q

when can glucocorticoids promote edema

A

when given at pharmaceutical levels to decrease inflammation

49
Q

importance of potassium

A

affects RMP in neurons and muscle cells (specifically heart muscle)

50
Q

hyperkalemia

A

increase in K+ ECF, leading to decreased RMP (depolarization of cell)

51
Q

hypokalemia

A

decrease in K+ ECF, leading to increased RMP (hyperpolarization of cell)

52
Q

hyperkalemia and hypokalemia lead to

A

disrupted electrical conduction in the heart - can result in arrythmias, arrest, or death

53
Q

regulation of potassium balance

A

controlled in collecting ducts by regulating the amount of secretion into filtrate
most important factor is concentration in ECF

54
Q

adrenal cortical cells are directly sensitive to

A

the K+ content of ECF to cause aldosterone release

55
Q

main storage of calcium in the body (99%)

A

in bones as calcium phosphate salts

56
Q

calcium in the ECF is important for

A

blood clotting
cell membrane signals
secretion of NTs
neuromuscular excitability

57
Q

hypocalcemia leads to

A

increased excitability

58
Q

hypercalcemia leads to

A

inhibition - can lead to arrythmias in the heart

59
Q

calcium balance is controlled by

A

parathyroid hormone from the parathyroid gland

60
Q

PTH and bones

A

results in overall breakdown, leading to calcium being released into the blood

61
Q

PTH and kidneys

A

increases calcium reabsorption from filtrate (causes retention)

62
Q

PTH and the small intestine

A

activates vitamin D, leading to Ca++ reabsorption from food

63
Q

Cl- is a major anion in _____

A

ECF

64
Q

function of chloride

A

helps maintain the osmotic pressure of blood and ECF

65
Q

under normal pH conditions, 99% of Cl- is with

A

Na+

66
Q

normal pH of body fluids

A

7.35-7.45

67
Q

alkalosis or alkalemia

A

arterial pH >7.45

68
Q

acidosis or acidemia

A

arterial pH < 7.35

69
Q

most H+ is produced by

A

metabolism

70
Q

phosphoric acid comes from

A

phosphate in H2O into ECF

71
Q

lactic acid comes from

A

anaerobic respiration of glucose

72
Q

fatty acids and ketones come from

A

fat metabolism

73
Q

carbonic acid is made when

A

CO2 combines with water

74
Q

acid-base balance is regulated by

A

chemical buffer systems (milliseconds)
respiratory centers in the brain (minutes)
renal mechanisms (hours to days)

75
Q

strong acids + water

A

complete dissociation (H+Cl- -> H+ + Cl-)

76
Q

weak acids + water

A

partial dissociation (H2CO3 <-> H+ + HCO3-)

77
Q

strong bases + water

A

easily dissociate (Na+OH- -> Na+ + OH-)

78
Q

weak bases + water

A

accept H+ slowly (Na+HCO3-)

79
Q

chemical buffer systems are combinations of

A

weak acid and weak base

80
Q

most important buffer system

A

bicarbonate buffer system

81
Q

bicarbonate buffer system

A

mixture of carbonic acid (weak) and salts of bicarbonate (weak bases)

82
Q

strong acid + bicarbonate buffer system

A

strong acid + weak base -> weak base + salt (NA+OH- + H2CO3 ->Na+HCO3- + H2O)

83
Q

strong base + bicarbonate buffer system

A

strong base + weak acid -> weak base + water (HCl + NaHCO3 -> H2CO3 + NaCl)

84
Q

phosphate buffer system

A

most important in urine
sodium salts of dihydrogen phosphate is a weak acid
sodium salts of monohydrogen phosphate is weak base

85
Q

protein buffer system

A

most important inside cells and in plasma
proteins can function as both a weak acid or base

86
Q

pH and the protein buffer system

A

rise: carboxyl (COOH) groups weaken base when more base is added to weak acid
fall: NH2 groups weaken acid when more acid is added to weak base

87
Q

respiratory mechanism of adjusting pH

A

adjusting CO2
acidic - increase respiration
basic - decrease respiration

88
Q

renal mechanism of adjusting pH

A

peeing out acid or base
reabsorbing/generating new HCO3- = H+ excretion
excreting HCO3- = H+ retention
excreting ammonium ion (excess acid)

89
Q

the ammonium ion is created from

A

amino acid glutamate

90
Q

causes of respiratory acidosis

A

hypoventilation
pulmonary disease
restriction
drug overdose
alcohol poisoning

91
Q

causes of respiratory alkalosis

A

hyperventilation
panic attacks
high altitudes

92
Q

indicator of respiratory acidosis or alkalosis

A

blood CO2

93
Q

indicator of metabolic acidosis or alkalosis

A

abnormal HCO3- levels

94
Q

metabolic acidosis

A

low pH and bicarbonate

95
Q

causes of metabolic acidosis

A

ketosis
diarrhea (loss of base)
alcohol (acetic acid + ketones)

96
Q

metabolic alkalosis

A

high pH and bicarbonate

97
Q

causes of metabolic alkalosis

A

vomiting (loss of acid)
antacid overdose