Biomedical Engineering 403
1997 Respiratory Section Exam
In addition to this exam, copies of the following exams are posted:
BME 403 Respiratory Section Exam (100pts max)
10-3-1997
** closed book **
All calculated results can be rounded to 2 decimal places.
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1. {15} Using a wet spirometer at 20 degrees C (water vapor pressure PH2O
=
17.5mmHg), a normal subject had a vital capacity of 5 liters at sea level.
-
(a) what is the volume in BTPS (barometric pressure PB=760mmHg, PH2O = 47
mmHg)?
-
(b) if the measurement was repeated with the same setup and
condition except at an altitude of 20,00ft (PB=349mmHg), and a vital
capacity of 4.74 liters was obtained, would you expect this to be
equivalent at sea level (justify your answer)?
-
(c) Would the altitude
affect it at all(Y/N)?
Answer
2. {10} (True/False):
- [ ] (a) vital capacity can be measured during
rest.
-
[ ] (b) body plethysmograph can be used to measure FRC.
-
[ ] (c) total lung capacity is the sum of residual volume and vital
capacity.
-
[ ] (d) spirometer can not be used to directly measure the residual
volume.
-
[ ] (e) minute-ventilation (L/min) can be obtained from expiratory
tidal
volume using a spirometer.
Answer
3. {10} An expiratory tidal volume (VT) is the sum of the dead space (VD)
and the alveolar volume (VA). If CO2 is measured at inspiration with
FICO2 (fractional concentration), at expired volume FECO2, and at end of
expiration with a rapid CO2 analyzer FeCO2.
-
(a) use mass-balance to write
down the equation for the total CO2 volume.
-
(b) From above 2 equations
derive an equation for obtaining VD in terms of the above CO2 fractional
concentrations and VT.
-
(c) If VT= 500ml, FICO2=0%, FeCO2=5.6%, FECO2=3%,
find the VD.
Answer
4. {15} A man with normal lungs and arterial PCO2 of 40 mmHg takes an
overdoes of barbiturate which halves his alveolar ventilation but does not
change his CO2 output.
-
(a) What will his arterial PCO2 rise to?
-
(b) If
his respiratory exchange ratio is 0.8, approximately how much will his
arterial PO2 fall?
-
(c) How much does the inspired O2 concentration have
to be raised to abolish the hypoxemia?
Answer
5. {2} How is O2 be carried in the blood: by
-
(a) binding to hemoglobin
only
- (b) dissolved in the plasmas only
- (c) both.
Answer
6. {15}
- (a) How does respiratory acidosis affect the blood pH?
- (b) Is
respiratory acidosis caused by PCO2 or by bicarbonate?
- (c) What kind of
compensation will be activated to restore the normal pH?
- (d) Does
metabolic acidosis have the same effect on pH as respiratory acidosis?
Answer
7. {3} The main function of the surfactant is to
-
(a) increase the lung
volume
-
(b) increase the alveolar surface tension
- (c) prevent collapse of
alveolus.
Answer
8. {10}
-
(a) Which one is the major respiratory muscle: intercostal muscle
or diaphragm?
-
(b) During expiration, which pressure is higher (less
negative) – alveolar or intrapleural?
- (c) During a breathing cycle, which
part of mechanical work is recoverable – resistive work or elastic work?
-
(d) Is alveolar liquid-gas interface contribute to the total elasticity of
the lungs (Y/N)?
Answer
9. {10}
-
(a)Which of the following arterial blood variables the
respiratory control system regulate:
-
(1) PO2
- (2) PCO2
- (3) pH
-
(4) all of
them.
- (b) Is central chemoreceptors most sensitive to PO2 or PCO2 change?
- (c) If arterial PCO2 is normal (<40 mmHg) and PO2 is dropped
from its
normal value of 100 mmHg to 90 mmHg, would this causes a dramatic
ventilation increase? Why?
Answer
10. {10} During moderate muscular exercise, the ventilation will
increase.
-
(a) Will the arterial PO2 be elevated accordingly or remains
the same?
-
(b) The level of the blood lactic acid will be increased due to
anaerobic glycolysis, will this increase the arterial greatly pH?
-
(c) Can
exercise be explained with a control system model? Why?
Answer
Some useful equations:
PV = nRT, or PV = k at a constant T
. .
P = ( V / V ) * k
ACO2 CO2 A
. .
P = P - ( V / V ) * k
AO2 IO2 O2 A
P = P - ( P / R )
AO2 IO2 ACO2
. .
R = ( V / V )
CO2 O2
END OF EXAM
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