Download 1. In which of the following fluids is the pH highest (most alkaline

1. In which of the following fluids is the pH highest
(most alkaline)? (Assume the person is normal.)
A. systemic arterial blood plasma
B. systemic venous blood plasma
C. urine
D. all of the above, since pH is normally of the same for
all
E. A and B above, since blood plasma pH is relatively
uniform
2. The ammonium (NH4+) ion that may be present in urine is
produced by
A. breakdown of urea in the liver
B. metabolism of amino acids in the renal tubule and
collecting duct
C. aerobic carbohydrate metabolism
D. gylcolytic pathways during anaerobic metabolism
E. gluconeogensis during starvation
3. The reason that respiratory compensation for metabolic
alkalosis can never be complete (return plasma pH to
normal) is that (Note: PaCO2 = systemic arterial carbon
dioxide partial pressure.)
A. high PaCO2 inhibits respiratory ventilation
B. high PaCO2 stimulates respiratory ventilation
C. low PaCO2 inhibits respiratory ventilation
D. low PaCO2 stimulates respiratory ventilation
E. none of the above, since respiratory compensation for
metabolic alkalosis can be complete
4. The appearance of large amounts of ammonium ion (NH4+)
in the urine is characteristic of the renal response to
A.
B.
C.
D.
E.
respiratory acidosis
respiratory alkalosis
acidosis resulting from pancreatic diabetes
alkalosis resulting from gastric vomiting
both A and C above
5. An individual hoping for an LSD "acid high" mistakenly
gives himself an intravenous injection of hydrochloric
acid. The responses of his body which attempt to
compensate for this ignorance of physiology include all
of the following except
A.
B.
C.
D.
E.
hyperventilation
increase in the acid form of the blood fixed buffers
decrease in blood bicarbonate ion concentration
increase in urine bicarbonate ion excretion
increase in urine ammonium ion excretion
6. A systemic arterial blood sample taken from the above
individual an hour after his HCl "adventure" might show
which of the following?
A.
B.
C.
D.
E.
base
base
base
base
base
excess
excess
excess
excess
excess
=
=
=
=
=
+10 meq/liter; PaCO2
+10 meq/liter; PaCO2
-10 meq/liter; PaCO2
-10 meq/liter; PaCO2
0 meq/liter; PaCO2 =
= 50 mmHg
= 30 mmHg
= 50 mmHg
= 30 mmHg
40 mmHg
7. A young woman is found comatose, having taken an
unknown number of sleeping pills an unknown time before.
An arterial blood sample yields the following values:
pH
HCO3PaCO2
7.02
14 meq/liter
68 mmHg
This patient's acid-base status is most accurately
described as
A.
B.
C.
D.
E.
uncompensated metabolic acidosis
uncompensated respiratory acidosis
simultaneous respiratory and metabolic acidosis
respiratory acidosis with partial renal compensation
respiratory acidosis with complete renal compensation
ANSWERS
1. A. Systemic arterial blood has a higher (more
alkaline) pH than systemic venous blood because of the
CO2 added by metabolizing cells as blood passes through
the systemic vascular beds. Urine is generally more acid
than plasma because of the necessity of excreting the
excess fixed (non-volatile) acids created by metabolism.
2. B.
3. B. Respiratory compensation for metabolic alkalosis
involves depression of alveolar ventilation to accumulate
CO2. However, the higher PaCO2 stimulates ventilation,
which prevents complete compensation (return of pH to
7.4).
4. E. Renal compensation for acidosis, of both
respiratory and metabolic origin (assuming the metabolic
acidosis is not due to renal pathology), involves
synthesis of NH3 and subsequent excretion of NH4+.
5. D. Renal compensation for acidosis involves
bicarbonate reabsorption, not bicarbonate excretion.
6. D. After an hour, we should expect respiratory
compensation but not renal compensation. Thus, there will
be a negative base excess due to the acid injection and
low PaCO2 due to the hyperventilation.
7. C. The low pH indicates acidosis. The low bicarbonate
indicates metabolic acidosis. The high PaCO2indicates
respiratory acidosis. Presumably, the narcotic overdose
depressed the patient's respiratory center in the brain,
reducing ventilation. The reduction of available oxygen
then caused cellular anaerobic metabolism to increase,
leading to production of lactic acid, etc.