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Anatomy and Physiology > fluid, electrolyte, and acid-base balance > Flashcards

fluid, electrolyte, and acid-base balance Flashcards

1
Q

fluid sequestration

A

excess accumulation in a particular location

- total body water may be normal, but circulating blood volume may drop low enough to cause circulatory shock

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2
Q

edema

A

most common form of fluid sequestration

- accumulation of fluid in interstitial (ECF) spaces which causes swelling

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3
Q

pleural effusion

A

several liters of fluid can accumulate in the pleural cavity
- causes include some lung infections

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4
Q

hemorrhage

A

can cause fluid sequestration

- blood that pools in the tissue is lost to circulation

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5
Q

dehydration (negative fluid balance)

A

body eliminates WAY more water than sodium, ECF osmolarity rises
- affects all fluid compartments (ICF, blood, and tissue fluid)

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6
Q

causes of dehydration

A

lack of drinking water, diabetes, ADH hypo-secretion (diabetes insipidus), profuse sweating, overuse of diuretics

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7
Q

what age group is more vulnerable to dehydration?

A

infants, due to high metabolic rate which demands high urine excretion
- immature kidneys cannot concentrate urine effectively, greater ratio of body surfaces to volume

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8
Q

fluid replacement therapy

A
  • drinking water (doesnt replace electrolytes tho)
  • enema
  • parenteral routes
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9
Q

enema

A

type of fluid replacement therapy

- fluid absorbed through the colon

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10
Q

parenteral routes

A

fluid administration other than digestive tract

  • IV route
  • subcutaneous
  • intramuscular
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11
Q

different ways the body regulates fluid intake

A
  1. osmoreceptors in hypothalamus
    - respond to angiotensin 2 produced when BP drops
    - responds to a rise in osmolarity of ECF
  2. Hypothalamus signals pituitary to produce antidiuretic hormone (ADH)
    - promotes water conservation
  3. Cerebral cortex produces conscious sense of thirst
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12
Q

why does the hypothalamus produce an antidiuretic hormone (ADH)?

A

ADH promotes water conservation which regulates fluid intake

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13
Q

what does the cerebral cortex produce (regulation of fluid intake)?

A

conscious sense of thirst

  • intense thirst with increase in plasma osmolarity or blood volume goes down
  • salivation is inhibited with thirst (sympathetic signals from thirst center to salivary glands)
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14
Q

short-term inhibition of thirst

A

last 30-45 min

  • mouth cooling and moistening quenches thirst
  • distension of stomach and SI
  • prevents over drinking
  • w/out water thirst returns
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15
Q

long-term inhibition of thirst

A

30+ minutes

  • absorption of water from SI reduces osmolarity in blood
  • stops osmoreceptor response, promotes capillary filtration, and makes saliva more abundant and watery
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16
Q

ONLY way to control water output significantly

A

variation in urine volume
- slow rate of water and electrolyte loss until water and electrolytes can be ingested (kidneys cannot replace water or electrolytes)

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17
Q

variation in urine volume/fluid output mechanisms

A
  1. limit water output
  2. adjust electrolyte reabsorption
  3. as Na+ is reabsorbed or excreted, water follows!!
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18
Q

water output is limited through what hormone:

A

ADH (antidiuretic)- secretion is triggered by hypothalamic osmoreceptors in response to dehydration
-causes kidneys to release less water, decreasing amount of urine produced. high ADH level causes body to produce less urine. low level results in greater urine production

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19
Q

ADH is an example of what type of feedback?

A

ADH system is NEGATIVE feedback

  • if osmolarity rises or blood volume falls, more ADH is released
  • if osmolarity falls or blood volume rises, ADH release is inhibited, so tubules reabsorb less water, urine output increases, and these trends are reversed
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20
Q

functions of electrolytes

A
  1. participate in metabolism
  2. determine electrical potential (charge difference) across cell membranes
  3. strongly affect osmolarity of body fluids
  4. affects bodys water content and distribution
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21
Q

major cations in electrolyte balance

A

Na+, K+, Ca2+, Mg2+, H+

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22
Q

major anions in electrolyte balance

A

Cl-, HCO3-(bicarbonate) and PO4-

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23
Q

sodium

A

cation in extracellular fluid, accounts for 90-95% of osmolarity in ECF (sensed by hypothalamus)
- MOST significant solute in total body water and distribution

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24
Q

sodium electrical signaling is important in

A

nerve and muscle cells

  • resting membrane potential
  • inflow of Na+ through channels is essential to depolarization in nerve and muscle action potentials
25
Q

aldosterone

A

“salt-retaining hormone”

  • adrenal cortex secretes aldosterone
  • hyponatremia and hyperkalemia (low Na+, and too high K levels) directly stimulates the adrenal cortex to secrete aldosterone
  • renin-angiotensin-aldosterone mechanism
  • Renin is produced by the kidneys and controls the activation of the hormone angiotensin 1 and2, which stimulates the adrenal glands to produce aldosterone
26
Q

hypotension (low BP) stimulates its secretion by

A

way of the renin-angiotensin-aldosterone mechanism

  • bc aldosterone is released when BP is low so this mechanism is used
  • raises salt levels which increases blood pressure
27
Q

distal convoluted tubule has what type of receptors?

A

aldosterone receptors

  • activates transcription of a gene for tubular Na+-K+ pumps (pumps are interested into plasma membrane)
  • tubules reabsorb more sodium and secrete more hydrogen and potassium
  • water and chloride passively follow sodium
28
Q

sodium imbalances

A

ex. secondary hyponatremia
- elevated BP inhibits renin-angiotensin-aldosterone mechanism (sodium cant be absorbed as well bc aldosterone is not being secreted)
- kidneys reabsorb almost no sodium

29
Q

potassium functions

A
  1. electrical signaling in nerve and muscle cells
    - responsible for resting membrane
    - repolarization and hyperpolarization of the action potential
  2. abundant cation of INTRACELLULAR fluid
  3. greatest determinant in intracellular osmolarity and cell volume
    * 90% in glomerular filtrate is reabsorbed by PCT
30
Q

acids, bases, and buffers

A

very important aspects of homeostasis

  • slight change in pH can shut down entire metabolic pathway
  • metabolism depends on enzymes and enzymes are sensitive to pH
31
Q

metabolism depends on

A

enzymes, and enzymes are sensitive to pH

32
Q

challenges in acid-base balance:

A
  • metabolism constantly produces acid which can throw off pH levels affecting enzymes
  • lactic acids from anaerobic fermentation
  • carbonic acid from carbon monoxide
33
Q

what is the pH of a solution mainly determined by?

A

hydrogen ions

34
Q

acids

A

any chemical that releases H+ into a solution

  • strong acids ionizes freely (gives up most of its H+ and lowers pH)
  • weak acids ionize only slightly (keeps most H+ and doesn’t affect pH much)
35
Q

bases

A

any chemical that accepts H+

  • strong bases usually bind to H+, which raises pH
  • weak bases bind less to H+, and don’t affect pH much
36
Q

buffer

A

any mechanism that resists changes in pH

- converts strong acids or bases to weak ones

37
Q

physiological buffer

A

system that controls output of acids, bases, or CO2

  • urinary system takes several hours or days to exert its acid or base affects
  • respiratory system buffers within minutes and cannot alter pH as much and urinary system
38
Q

bicarbonate buffer system

A

solution of carbonic acid and bicarbonate ions (participate in reversible reactions)

  • the direction of the reaction determines whether it raises or lowers pH
  • LOWERS pH by releasing H+
  • RAISES pH by binding H+
39
Q

bicarbonate buffer system coordinates with

A

the lungs and kidneys to help control pH and CO2

  • to lower pH, kidneys excrete HCO3- (bicarbonate)
  • to raise pH, kidneys excrete h+ and lungs excrete CO2 (kidneys get rid of acid)
40
Q

respiratory control of pH

A

bicarbonate buffer system is the basis for the strong buffering capacity of the respiratory system

  • addition of CO2 to body fluids raise the H+ conc. and lowers pH
  • removal of CO2 has opposite affects
  • neutralizes more acid as chemical buffers
41
Q

respiratory control of pH with CO2

A

CO2 is constantly produced by aerobic metabolism

  • CO2 from metabolism lowers pH by releasing H+
  • CO2 expired from lungs raises pH by binding H+
42
Q

CO2 affects on pulmonary ventilation

A
  • increased CO2 and decreased pH stimulates pulmonary ventilation
  • increased pH inhibits pulmonary ventilation
43
Q

renal control of pH

A

kidneys can neutralize more acid or base than either the respiratory system or chemical buffers
- renal tubules secrete H+ into the tubular fliud

44
Q

renal tubules secrete:

A

H+ into tubular fluid

  • most bind to bicarbonate, ammonia, and buffers
  • bound and free H+ are excreted in the urine which expells H+ from the body
45
Q

kidneys regulate long-term acid-base balance via

A

blood bicarbonate concentration

  • conservation (reabsorption) of HCO3-
  • generate new HCO3- via H+ secretion
46
Q

acidosis

A

pH below 7.35
- H+ diffuses into cells and drives out K+, elevating K+ conc. in ECF (causes hyperpolarization and nerve and muscle cells are hard to stimulate)

47
Q

alkalosis

A

pH above 7.45

- H+ diffuses out of cells and K+ diffuses in (membrane depolarizes, nerves overstimulate causing spasms and more)

48
Q

a person can not live w/ this pH for more than a few hours

A

if the blood pH is below 7.0 or above 7.7

49
Q

respiratory acidosis

A

occurs when rate of alveolar respiration fails to keep pace with the bodys rate of CO2 production (hyperventilation)
- CO2 accumulates in ECF and lowers pH

50
Q

respiratory alkalosis

A

results from hyperventilation

- CO2 eliminated faster than it is produced

51
Q

metabolic acidosis

A

increased production of organic acids (lactic acid) in anaerobic fermentation

  • ingestion of acidic drugs (asperin)
  • loss of base due to chronic diarrhea
52
Q

metabolic alkalosis

A

rare, but can result from overuse of bicarbonates (antacids)
- loss of stomach acid from chronic vomiting

53
Q

compensated acidosis or alkalosis

A
  • either kidneys compensate for pH imbalances of respiratory origin, or
  • respiratory system compensates for pH imbalances of metabolic origin
54
Q

uncompensated acidosis or alkalosis

A

pH imbalance that the body cannot correct without clinical intervention

55
Q

respiratory compensation

A

changes in pulmonary ventilation to correct changes in pH of body fluids by expelling or retaining CO2

56
Q

hypercapnia

A

excess CO2 from hypoventilation

- stimulates an increase in pulmonary ventilation, eliminating CO2 and pH increases

57
Q

hypocapnia

A

lower CO2 from hyperventilation

58
Q

renal compensation

A

pH adjusted by changing rate of H+ secretion of kidneys

  • slows but better at restoring fully normal pH
  • renal tubules increase rate of H+ secretion increasing pH
59
Q

short term pH is not fixed by

A

the kidneys, they cannot act quickly enough to compensate for short-term pH imbalances

Anatomy and Physiology (6 decks)

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