NURS 271 EXAM #1 UPDATED ACTUAL
Questions and CORRECT Answers
*ACID-BASE IMBALANCES* - CORRECT ANSWER
What is homeostasis? - CORRECT ANSWER = balance between acids & bases in the body
*without balance our cells can't function properly!
> H+ conc = measured by pH levels (inversely proportional) & are responsible for the acidity/alkalinity of
the body
- incr H+ conc = decr pH = acidosis
- decr H+ conc = incr pH = alkalosis
What pH indicates a normal acid base balance? acidosis? alkalosis? - CORRECT ANSWER -
normal pH = 7.35-7.45
- acidosis pH < 7.35
- alkalosis pH > 7.45
What are the normal Arterial Blood Gas (ABG) values? - CORRECT ANSWER *we collect arterial
blood to assess acid-base balance...
> pH = 7.35-7.45
> PaCO2 (partial. pressure of CO2 in arterial blood) = 35-45 mm/Hg
- indicates pts breathing effectiveness (respiratory component)
> HCO3- (bicarbonate) = 22-26 mEq/L
- indicates effectiveness of renal regulation of metabolic acids (metabolic component)
> PaO2 (partial pressure of O2) = 80-100 mm/Hg
- indicates pts oxygenating effectiveness
> SaO2 = 95-100%
What are chemical buffers? - CORRECT ANSWER = chemicals (weak. acid + base) found in all
body fluids that regulate pH by combining w excess acids & bases
,*1st line of defense against acid base imbalances (aka buffers system)
1) bicarbonate = buffers extracellular fluid (blood & interstitial fluid)
ex: respiratory & renal systems
2) phosphate = buffers intracellular & renal tubular fluids
ex: renal tubules
3) protein = buffers intracellular fluid & blood
ex: albumin & plasma proteins (most plentiful in body!)
Explain the bicarbonate buffer system. - CORRECT ANSWER = HCO3- (bicarbonate base) &
H2CO3 (weak carbonic acid) that compose the most important buffer in extracellular fluid!
- normal blood pH = normal HCO3-:H2CO3 = 20:1 *when this ratio deviates, the blood pH is altered
- MOA...
> excess metabolic acid = HCO3- uses H+ to form H2CO3 > carbonic anhydrase (enzyme) excretes
H2CO3 as CO2 & H2O via the respiratory tract
> lack of metabolic acid = H2CO3 releases H+ ions
How do the lungs regulate blood pH? - CORRECT ANSWER *lungs = 2nd line of defense against
acid base imbalances
- 2x more effective than chemical buffers w rapid response BUT temporary changes
> regulates blood levels of CO2 (PaCO2)
- base < avg 35-45 mmHg > acid
- chemoreceptors in the adrenal medulla = control breathing rate & depth
T or F: Any injury to the function of the respiratory system, chemoreceptors, respiratory neurons,
muscles, nerves, etc can result in impaired carbonic acid production. - CORRECT ANSWER T
How do the lungs compensate for acid-base imbalances resulting from altered levels of metabolic acids?
(aka respiratory compensation) - CORRECT ANSWER = lungs excrete CO2 & H2O in response to
altered metabolic acid levels
- CO2 (continuously produced by cells) + H2O → H2CO3 (carbonic acid)
,*carbonic acid is excreted normally when we exhale... by adjusting the rate & depth of our respiration
(via chemoreceptors) we can control the amt of carbonic acid in our body
> metabolic acidosis (excess metabolic acids, lack of HCO3-, & decr pH) = hyperventilation = decr CO2
in blood > decr H2CO3 > decr acidity (incr pH)
> metabolic alkalosis (lack of metabolic acids, incr pH, & excess HCO3-) = hypoventilation = incr CO2
in blood > incr H2CO3 > incr acidity (decr pH)
Explain the pathophysiology of *respiratory acidosis*. - CORRECT ANSWER = pH < 7.40 &
PaCO2 >45
E) processes that lead to hypoventilation & apnea
ex: morbid obesity, lung diseases, COPD, opiate overdose, hypokalemia (muscle paralysis), chest trauma,
& foreign body aspiration
P) alveolar hypoventilation, decr respirations, inadequate gas exchange > incr PaCO2 (hypercapnia) >
decr pH
S/Sx) headache, altered LOC (blurred vision, tremors, vertigo, disorientation, lethargy), restlessness,
tachypnea, tachycardia, sweating
- risk for peripheral vasodilation, hypotension, & cardiac dysrhythmias/arrest
Tx) focused on improving ventilation to decr PaCO2 & incr pH *depends on underlying cause
- Bronchodilator > ex: Albuterol (Proventil) = dilates bronchioles & improves gas exchange
- Mucolytic > ex: Acetylcysteine (Mucomyst) = thins secretions & allows pts to cough them up
- Oxygen therapy = tx low SaO2
- Ventilatory support = controls gas exchange rate for pt
RENAL COMPENSATION: kidneys retain H+ & excrete HCO3- = incr HCO3- conc > decr H+ conc >
incr pH
Explain the pathophysiology of *respiratory alkalosis*. - CORRECT ANSWER = pH > 7.40 &
PaCO2 < 35
E) processes that lead to hyperventilation
ex: psychological stress, acute pain, hypoxemia, palpitations, fever, & sepsis (pneumonia, UTIs, e . coli)
, P) alveolar hyperventilation, incr respirations, excessive gas exchange > decr PaCO2 (hypocapnia) > incr
pH
S/Sx) incr neuromuscular excitability (extremity/mouth paresthesias), lightheadedness, confusion,
anxiety, restlessness, ECG changes (tachycardia & prolonged PR intervals)
Tx) *depends on underlying cause
- antipyretics > ex: tylenol or ibuprofen
- eliminate sepsis source > ex: antibiotics
- oxygen therapy
- administer sedative > ex: valium or xanax
RENAL COMPENSATION: kidneys excrete H+ & retain HCO3- = decr HCO3- conc > incr H+ conc >
slightly decr pH
How do the kidneys regulate blood pH? - CORRECT ANSWER *kidneys = 3rd line of defense
against acid-base imbalances
- longer term changes BUT longer process
> regulates bicarbonate levels (HCO3-)
- acid < avg 22-26 mEq/L > base
- reabsorbs acids & bases & excretes them in urine
T or F: Any injury to the function of the renal system can result in impaired metabolic acid regulation. -
CORRECT ANSWER T
> Infants & older adults have less efficient acid excretion mechanisms.
How do the kidneys compensate for acid-base imbalances resulting from altered levels of carbonic acid?
(aka renal compensation) - CORRECT ANSWER = kidneys excrete metabolic acids (ex:
bicarbonate) in response to altered carbonic acid levels
- metabolic acids = acids that are not carbonic acids & produced continuously during normal metabolism
*kidneys secrete H+ into renal tubular fluid & produce ammonium (NH4+) > decr pH & incr acidity
- for every H+ secreted into the renal tubular fluid, a HCO3- is moved into the interstitial fluid
Questions and CORRECT Answers
*ACID-BASE IMBALANCES* - CORRECT ANSWER
What is homeostasis? - CORRECT ANSWER = balance between acids & bases in the body
*without balance our cells can't function properly!
> H+ conc = measured by pH levels (inversely proportional) & are responsible for the acidity/alkalinity of
the body
- incr H+ conc = decr pH = acidosis
- decr H+ conc = incr pH = alkalosis
What pH indicates a normal acid base balance? acidosis? alkalosis? - CORRECT ANSWER -
normal pH = 7.35-7.45
- acidosis pH < 7.35
- alkalosis pH > 7.45
What are the normal Arterial Blood Gas (ABG) values? - CORRECT ANSWER *we collect arterial
blood to assess acid-base balance...
> pH = 7.35-7.45
> PaCO2 (partial. pressure of CO2 in arterial blood) = 35-45 mm/Hg
- indicates pts breathing effectiveness (respiratory component)
> HCO3- (bicarbonate) = 22-26 mEq/L
- indicates effectiveness of renal regulation of metabolic acids (metabolic component)
> PaO2 (partial pressure of O2) = 80-100 mm/Hg
- indicates pts oxygenating effectiveness
> SaO2 = 95-100%
What are chemical buffers? - CORRECT ANSWER = chemicals (weak. acid + base) found in all
body fluids that regulate pH by combining w excess acids & bases
,*1st line of defense against acid base imbalances (aka buffers system)
1) bicarbonate = buffers extracellular fluid (blood & interstitial fluid)
ex: respiratory & renal systems
2) phosphate = buffers intracellular & renal tubular fluids
ex: renal tubules
3) protein = buffers intracellular fluid & blood
ex: albumin & plasma proteins (most plentiful in body!)
Explain the bicarbonate buffer system. - CORRECT ANSWER = HCO3- (bicarbonate base) &
H2CO3 (weak carbonic acid) that compose the most important buffer in extracellular fluid!
- normal blood pH = normal HCO3-:H2CO3 = 20:1 *when this ratio deviates, the blood pH is altered
- MOA...
> excess metabolic acid = HCO3- uses H+ to form H2CO3 > carbonic anhydrase (enzyme) excretes
H2CO3 as CO2 & H2O via the respiratory tract
> lack of metabolic acid = H2CO3 releases H+ ions
How do the lungs regulate blood pH? - CORRECT ANSWER *lungs = 2nd line of defense against
acid base imbalances
- 2x more effective than chemical buffers w rapid response BUT temporary changes
> regulates blood levels of CO2 (PaCO2)
- base < avg 35-45 mmHg > acid
- chemoreceptors in the adrenal medulla = control breathing rate & depth
T or F: Any injury to the function of the respiratory system, chemoreceptors, respiratory neurons,
muscles, nerves, etc can result in impaired carbonic acid production. - CORRECT ANSWER T
How do the lungs compensate for acid-base imbalances resulting from altered levels of metabolic acids?
(aka respiratory compensation) - CORRECT ANSWER = lungs excrete CO2 & H2O in response to
altered metabolic acid levels
- CO2 (continuously produced by cells) + H2O → H2CO3 (carbonic acid)
,*carbonic acid is excreted normally when we exhale... by adjusting the rate & depth of our respiration
(via chemoreceptors) we can control the amt of carbonic acid in our body
> metabolic acidosis (excess metabolic acids, lack of HCO3-, & decr pH) = hyperventilation = decr CO2
in blood > decr H2CO3 > decr acidity (incr pH)
> metabolic alkalosis (lack of metabolic acids, incr pH, & excess HCO3-) = hypoventilation = incr CO2
in blood > incr H2CO3 > incr acidity (decr pH)
Explain the pathophysiology of *respiratory acidosis*. - CORRECT ANSWER = pH < 7.40 &
PaCO2 >45
E) processes that lead to hypoventilation & apnea
ex: morbid obesity, lung diseases, COPD, opiate overdose, hypokalemia (muscle paralysis), chest trauma,
& foreign body aspiration
P) alveolar hypoventilation, decr respirations, inadequate gas exchange > incr PaCO2 (hypercapnia) >
decr pH
S/Sx) headache, altered LOC (blurred vision, tremors, vertigo, disorientation, lethargy), restlessness,
tachypnea, tachycardia, sweating
- risk for peripheral vasodilation, hypotension, & cardiac dysrhythmias/arrest
Tx) focused on improving ventilation to decr PaCO2 & incr pH *depends on underlying cause
- Bronchodilator > ex: Albuterol (Proventil) = dilates bronchioles & improves gas exchange
- Mucolytic > ex: Acetylcysteine (Mucomyst) = thins secretions & allows pts to cough them up
- Oxygen therapy = tx low SaO2
- Ventilatory support = controls gas exchange rate for pt
RENAL COMPENSATION: kidneys retain H+ & excrete HCO3- = incr HCO3- conc > decr H+ conc >
incr pH
Explain the pathophysiology of *respiratory alkalosis*. - CORRECT ANSWER = pH > 7.40 &
PaCO2 < 35
E) processes that lead to hyperventilation
ex: psychological stress, acute pain, hypoxemia, palpitations, fever, & sepsis (pneumonia, UTIs, e . coli)
, P) alveolar hyperventilation, incr respirations, excessive gas exchange > decr PaCO2 (hypocapnia) > incr
pH
S/Sx) incr neuromuscular excitability (extremity/mouth paresthesias), lightheadedness, confusion,
anxiety, restlessness, ECG changes (tachycardia & prolonged PR intervals)
Tx) *depends on underlying cause
- antipyretics > ex: tylenol or ibuprofen
- eliminate sepsis source > ex: antibiotics
- oxygen therapy
- administer sedative > ex: valium or xanax
RENAL COMPENSATION: kidneys excrete H+ & retain HCO3- = decr HCO3- conc > incr H+ conc >
slightly decr pH
How do the kidneys regulate blood pH? - CORRECT ANSWER *kidneys = 3rd line of defense
against acid-base imbalances
- longer term changes BUT longer process
> regulates bicarbonate levels (HCO3-)
- acid < avg 22-26 mEq/L > base
- reabsorbs acids & bases & excretes them in urine
T or F: Any injury to the function of the renal system can result in impaired metabolic acid regulation. -
CORRECT ANSWER T
> Infants & older adults have less efficient acid excretion mechanisms.
How do the kidneys compensate for acid-base imbalances resulting from altered levels of carbonic acid?
(aka renal compensation) - CORRECT ANSWER = kidneys excrete metabolic acids (ex:
bicarbonate) in response to altered carbonic acid levels
- metabolic acids = acids that are not carbonic acids & produced continuously during normal metabolism
*kidneys secrete H+ into renal tubular fluid & produce ammonium (NH4+) > decr pH & incr acidity
- for every H+ secreted into the renal tubular fluid, a HCO3- is moved into the interstitial fluid
