BRS Physiology (respiratory) review questions Flashcards
Which of the following lung volumes or capacities can be measured by spirometry? A. Functional Residual Capacity (FRC) B. Physiologic dead space C. Residual Volume (RV) D. Total lung capacity (TLC) E. Vital Capacity (VC)
E Residual volume (RV) cannot be measured by spirometry. Therefore, any lung volume or capacity that includes the RV cannot be measured by spirometry. Measurements that include RV are functional residual capacity (FRC) and total lung capacity (TLC). Vital capacity (VC) does not include RV and is, therefore, measurable by spirometry. Physiologic dead space is not measurable by spirometry and requires sampling of arterial PCO2 and expired CO2.
An infant is born prematurely in gestational week 25 has neonatal respiratory distress syndrome. Which of the following would be expected in this infant?
A. Aterial PO2 of 100 mmHg
B. Collapse of the small alveoli
C. Increased lung compliance
D. Normal breathing rate
E. Lecithin: sphingomyelin ratio of greater than 2:1 in amniotic fluid
B
Neonatal respiratory distress syndrome is caused by lack of adequate surfactant in the immature lung. Surfactant appears between the 24th and the 35th gestational week. In the absence of surfactant, the surface tension of the small alveoli is too high. When the pressure on the small alveoli is too high (P = 2T/r), the small alveoli collapse into larger alveoli. There is decreased gas exchange with the larger, collapsed alveoli, and ventilation/perfusion (V/Q) mismatch, hypoxemia, and cyanosis occur. The lack of surfactant also decreases lung compliance, making it harder to inflate
the lungs, increasing the work of breathing, and producing dyspnea (shortness of
breath). Generally, lecithin:sphingomyelin ratios greater than 2:1 signify mature levels of
surfactant.
In which vascular bed does hypoxia cause vasoconstriction? A. Coronary B. Pulmonary C. Cerebral D. Muscle E. Skin
B Pulmonary blood flow is controlled locally by the PO2 of alveolar air. Hypoxia causes pulmonary vasoconstriction and thereby shunts blood away from unventilated areas of the lung, where it would be wasted. In the coronary circulation, hypoxemia causes vasodilation. The cerebral, muscle, and skin circulations are not controlled directly by PO2.
A 12 yo boy has a severe asthmatic attack with wheezing. He experiences rapid breathing and becomes cyanotic. His arterial PO2 is 60 mmHg and his PCO2 is 30mmHg
Which of the following statements about this patient is most likely to be true?
A. Forces expiratory volume/forced vital capacity (FEV1/FVC) is increased
B. Ventilation/perfusion (V/Q) ratio is increased in the affected areas of his lungs
C. His arterial PCO2 is higher than normal because of inadequate gas exchange
D. His arterial PCO2 is lower than normal because hypoxemia is causing him to hyperventilate
E. His residual volume (RV) is decreased
D
The patient’s arterial PCO2 is lower than the normal value of
40 mm Hg because hypoxemia has stimulated peripheral chemoreceptors to increase his
breathing rate; hyperventilation causes the patient to blow off extra CO2 and results in
respiratory alkalosis. In an obstructive disease, such as asthma, both forced expiratory volume (FEV1) and forced vital capacity (FVC) are decreased, with the larger decrease
occurring in FEV1. Therefore, the FEV1/FVC ratio is decreased. Poor ventilation of the
affected areas decreases the ventilation/perfusion (V/Q) ratio and causes hypoxemia.
The patient’s residual volume (RV) is increased because he is breathing at a higher lung
volume to offset the increased resistance of his airways.
A 12 yo boy has a severe asthmatic attack with wheezing. He experiences rapid breathing and becomes cyanotic. His arterial PO2 is 60 mmHg and his PCO2 is 30mmHg
To treat this patient, the physician should administer
A. An alpha1 adrenergic antagonist
B. A beta1 adrenergic antagonist
C. A b2 adrenergic agonist
D. A muscarinic agonist
E. A nicotinic agonist
C
A cause of airway obstruction in asthma is bronchiolar constriction. β2-adrenergic stimulation (β2-adrenergic agonists) produces relaxation of the bronchioles.
Which of the following is true during inspiration?
A. Intrapleural pressure is positive
B. The volume in the lungs is less than the functional residual capacity (FRC)
C. Alveolar pressure equals atmospheric pressure
D. Alveolar pressure is higher than atmospheric pressure
E. Intrapleural pressure is more negative than it is during expiration
E
During inspiration, intrapleural pressure becomes more negative
than it is at rest or during expiration (when it returns to its less negative resting value). During inspiration, air flows into the lungs when alveolar pressure becomes lower (due
to contraction of the diaphragm) than atmospheric pressure; if alveolar pressure were
not lower than atmospheric pressure, air would not flow inward. The volume in the
lungs during inspiration is the functional residual capacity (FRC) plus one tidal volume
(TV).
Which volume remains in the lungs after a tidal volume (TV) is expired? A. Tidal volume (TV) B. vital capacity (VC) C. Expiratory reserve volume (ERV) D. Residual volume (RV) E. Functional residual capacity (FRC) F. Inspiratory capcity G. Total lung capacity
E
During normal breathing, the volume inspired and then expired is a tidal volume (TV). The volume remaining in the lungs after expiration of a TV is the functional residual capacity (FRC).
A 35 yo man has a vital capacity of 5L, a tidal volume of 0.5L, an inspiratory capacity of 3.5L, and a functional residual capcity of 2.5L. What is his expiratory reserve volume? A. 4.5L B. 3.9L C. 3.6L D. 3.0L E. 2.5L F. 2.0L G. 1.5L
G
Expiratory reserve volume (ERV) equals vital capacity
(VC) minus inspiratory capacity. [Inspiratory capacity includes tidal volume (TV) and
inspiratory reserve volume (IRV)].
When a person is standing, blood flow in the lungs is
A. equal at the apex and the base
B. highest at the apex owing to the effects of gravity on arterial pressure
C. highest at the base because that is where the difference between arterial and venous pressure is greatest
D. Lowest at the base because that is where alveolar pressure is greater than arterial pressure
C
The distribution of blood flow in the lungs is affected by gravita-
tional effects on arterial hydrostatic pressure. Thus, blood flow is highest at the base,
where arterial hydrostatic pressure is greatest and the difference between arterial and
venous pressure is also greatest. This pressure difference drives the blood flow.
Graph
C
Which of the following is the site of highest airway resistance? A. Trachea B. Largest bronchi C. Medium-sized bronchi D. Smallest bronchi E. Alveoli
C
The medium-sized bronchi actually constitute the site of highest
resistance along the bronchial tree. Although the small radii of the alveoli might predict that they would have the highest resistance, they do not because of their parallel arrangement. In fact, early changes in resistance in the small airways may be “silent” and go undetected because of their small overall contribution to resistance.
A 49 yo man has a pulmonary embolism that completely blocks blood flow to his left lung. As a result, which of the following will occur?
A. Ventilation/perfusion (V/Q) ratio in the left lung will be zero
B. Systemic arterial PO2 will be elevated
C. V/Q ratio in the left lung will be lower than in the right lung
D. Alveolar PO2 in the left lung will be approximately equal to the PO2 in inspired air
E. Alveolar PO2 in the right lung will be approximately equal to the PO2 in venous blood
D
Alveolar PO2 in the left lung will equal the PO2 in inspired air. Because there is no blood flow to the left lung, there can be no gas exchange between the alveolar air and the pulmonary capillary blood. Consequently, O2 is not added to the capillary blood. The ventilation/perfusion (V/Q) ratio in the left lung will be infinite (not zero or lower than that in the normal right lung) because Q (the denominator) is zero.
Systemic arterial PO2 will, of course, be decreased because the left lung has no gas exchange. Alveolar PO2 in the right lung is unaffected.
Which volume remains in the lungs after a maximal expiration A. Tidal volume B. Vital capacity C. Expiratory reserve volume D. Residual volume E. Functional reserve capacity F. Inspiratory capcity G. Total lung capacity
D
Compared with the systemic circulation, the pulmonary circulation has a A. Higher blood flow B. Lower resistance C. Higher arterial pressure D. Higher capillary pressure E. Higher cardiac output
B
Which volume remains in the lungs after a maximal expiration A. Tidal volume B. Vital capacity C. Expiratory reserve volume D. Residual volume E. Functional reserve capacity F. Inspiratory capcity G. Total lung capacity
D
During a forced maximal expiration, the volume expired is a tidal
volume (TV) plus the expiratory reserve volume (ERV). The volume remaining in the
lungs is the residual volume (RV).
