Deck 4: Respiratory Physiology

Question 1

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)

Answer 1

Vital capacity (VC)

Question 2

An infant born prematurely in gestational week 25 has neonatal respiratory distress syndrome. Which of the following would be expected in this infant?

A) Arterial $\mathrm{Po}_{2}$ of $100 \mathrm{~mm} \mathrm{Hg}$
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

Answer 2

Collapse of the small alveoli

Question 3

In which vascular bed does hypoxia cause vasoconstriction?

A) Coronary
B) Pulmonary
C) Cerebral
D) Muscle
E) Skin

Answer 3

Pulmonary

Question 4

A 12-year-old boy has a severe asthmatic attack with wheezing. He experiences rapid breathing and becomes cyanotic. His arterial $\mathrm{PO}_{2}$ is $60 \mathrm{~mm} \mathrm{Hg}$ and his $\mathrm{PCO}_{2}$ is $30 \mathrm{~mm} \mathrm{Hg}$ .

-Which of the following statements about this patient is most likely to be true?

A) Forced expiratory volume / forced vital $^{\text {f }}$ capacity $\left(\mathrm{FEV}_{1} / \mathrm{FVC}\right)$ is increased
B) Ventilation/perfusion (V/Q) ratio is increased in the affected areas of his lungs
C) His arterial $\mathrm{PCO}_{2}$ is higher than normal because of inadequate gas exchange
D) His arterial $\mathrm{PCO}_{2}$ is lower than normal because hypoxemia is causing him to hyperventilate
E) His residual volume (RV) is decreased

Question 5

A 12-year-old boy has a severe asthmatic attack with wheezing. He experiences rapid breathing and becomes cyanotic. His arterial $\mathrm{PO}_{2}$ is $60 \mathrm{~mm} \mathrm{Hg}$ and his $\mathrm{PCO}_{2}$ is $30 \mathrm{~mm} \mathrm{Hg}$ .

-To treat this patient, the physician should administer

A) an $\alpha_{1}$ -adrenergic antagonist
B) a $\beta_{1}$ -adrenergic antagonist
C) a $\beta_{2}$ -adrenergic agonist
D) a muscarinic agonist
E) a nicotinic agonist

Question 6

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

Question 7

Which volume remains in the lungs after a tidal volume ( $\left.\mathrm{V}_{\mathrm{T}}\right)$ is expired?

A) Tidal volume ( $\left.\mathrm{V}_{\mathrm{T}}\right)$
B) Vital capacity (VC)
C) Expiratory reserve volume (ERV)
D) Residual volume (RV)
E) Functional residual capacity (FRC)
F) Inspiratory capacity
G) Total lung capacity

Question 8

A 35-year-old man has a vital capacity (VC) of $5 \mathrm{~L}$ , a tidal volume ( $\mathrm{VT}$ ) of $0.5 \mathrm{~L}$ , an inspiratory capacity of $3.5 \mathrm{~L}$ , and a functional residual capacity (FRC) of $2.5 \mathrm{~L}$ . What is his expiratory reserve volume (ERV)?

A) $4.5 \mathrm{~L}$
B) $3.9 \mathrm{~L}$
C) $3.6 \mathrm{~L}$
D) $3.0 \mathrm{~L}$
E) $2.5 \mathrm{~L}$
F) $2.0 \mathrm{~L}$
G) $1.5 \mathrm{~L}$

Question 9

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

Question 10

Which of the following is illustrated in the graph showing volume versus pressure in the lung-chest wall system?

A) The slope of each of the curves is resistance
B) The compliance of the lungs alone is less than the compliance of the lungs plus chest wall
C) The compliance of the chest wall alone is less than the compliance of the lungs plus chest wall
D) When airway pressure is zero (atmospheric), the volume of the combined system is the functional residual capacity (FRC)
E) When airway pressure is zero (atmospheric), intrapleural pressure is zero

Question 11

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

Question 12

A 49-year-old 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 $\mathrm{PO}_{2}$ will be elevated
C) V/Q ratio in the left lung will be lower than in the right lung
D) Alveolar $\mathrm{PO}_{2}$ in the left lung will be approximately equal to the $\mathrm{PO}_{2}$ in inspired air
E) Alveolar $\mathrm{PO}_{2}$ in the right lung will be approximately equal to the $\mathrm{P}_{2}$ in venous blood

Question 13

-In the hemoglobin- $\mathrm{O}_{2}$ dissociation curves shown above, the shift from curve A to curve B could be caused by

A) increased $\mathrm{pH}$
B) decreased 2,3-diphosphoglycerate (DPG) concentration
C) strenuous exercise
D) fetal hemoglobin (HbF)
E) carbon monoxide (CO) poisoning

Question 14

-The shift from curve $A$ to curve $B$ is associated with

A) increased $\mathrm{P}_{50}$
B) increased affinity of hemoglobin for $\mathrm{O}_{2}$
C) impaired ability to unload $\mathrm{O}_{2}$ in the tissues
D) increased $\mathrm{O}_{2}$ -carrying capacity of hemoglobin
E) decreased $\mathrm{O}_{2}$ -carrying capacity of hemoglobin

Question 15

Which volume remains in the lungs after a maximal expiration?

A) Tidal volume ( $\mathrm{VT})$
B) Vital capacity (VC)
C) Expiratory reserve volume (ERV)
D) Residual volume (RV)
E) Functional residual capacity (FRC)
F) Inspiratory capacity
(G) Total lung capacity

Question 16

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

Question 17

A healthy 65 -year-old man with a tidal volume ( $\mathrm{VT}$ ) of $0.45 \mathrm{~L}$ has a breathing frequency of 16 breaths/min. His arterial $\mathrm{PCO}_{2}$ is $41 \mathrm{~mm} \mathrm{Hg}$ , and the $\mathrm{PCO}_{2}$ of his expired air is $35 \mathrm{~mm} \mathrm{Hg}$ . What is his alveolar ventilation?

A) $0.066 \mathrm{~L} / \mathrm{min}$
B) $0.38 \mathrm{~L} / \mathrm{min}$
C) $5.0 \mathrm{~L} / \mathrm{min}$
D) $6.14 \mathrm{~L} / \mathrm{min}$
E) $8.25 \mathrm{~L} / \mathrm{min}$

Question 18

Compared with the apex of the lung, the base of the lung has

A) a higher pulmonary capillary $\mathrm{PO}_{2}$
B) a higher pulmonary capillary $\mathrm{PCO}_{2}$
C) a higher ventilation/perfusion (V/Q) ratio
D) the same $V / Q$ ratio

Question 19

Hypoxemia produces hyperventilation by a direct effect on the

A) phrenic nerve
B) J receptors
C) lung stretch receptors
D) medullary chemoreceptors
E) carotid and aortic body chemoreceptors

Question 20

Which of the following changes occurs during strenuous exercise?

A) Ventilation rate and $\mathrm{O}_{2}$ consumption increase to the same extent
B) Systemic arterial $\mathrm{Po}_{2}$ decreases to about $70 \mathrm{~mm} \mathrm{Hg}$
C) Systemic arterial $\mathrm{PCO}_{2}$ increases to about $60 \mathrm{~mm} \mathrm{Hg}$
D) Systemic venous $\mathrm{PCO}_{2}$ decreases to about $20 \mathrm{~mm} \mathrm{Hg}$
E) Pulmonary blood flow decreases at the expense of systemic blood flow

Question 21

If an area of the lung is not ventilated because of bronchial obstruction, the pulmonary capillary blood serving that area will have a $\mathrm{PO}_{2}$ that is

A) equal to atmospheric $\mathrm{PO}_{2}$
B) equal to mixed venous $\mathrm{PO}_{2}$
C) equal to normal systemic arterial $\mathrm{Po}_{2}$
D) higher than inspired $\mathrm{PO}_{2}$
E) lower than mixed venous $\mathrm{Po}_{2}$

Question 22

In the transport of $\mathrm{CO}_{2}$ from the tissues to the lungs, which of the following occurs in venous blood?

A) Conversion of $\mathrm{CO}_{2}$ and $\mathrm{H}_{2} \mathrm{O}$ to $\mathrm{H}^{+}$ and $\mathrm{HCO}_{3}{ }^{-}$ in the red blood cells (RBCs)
B) Buffering of $\mathrm{H}^{+}$ by oxyhemoglobin
C) Shifting of $\mathrm{HCO}_{3}^{-}$ into the RBCs from plasma in exchange for $\mathrm{Cl}^{-}$
D) Binding of $\mathrm{HCO}_{3}{ }^{-}$ to hemoglobin
E) Alkalinization of the RBCs

Question 23

Which of the following causes of hypoxia is characterized by a decreased arterial $\mathrm{PO}_{2}$ and an increased A-a gradient?

A) Hypoventilation
B) Right-to-left cardiac shunt
C) Anemia
D) Carbon monoxide poisoning
E) Ascent to high altitude

Question 24

A 42-year-old woman with severe pulmonary fibrosis is evaluated by her physician and has the following arterial blood gases: $\mathrm{pH}=7.48, \mathrm{~Pa}_{\mathrm{O}_{2}}=55 \mathrm{~mm} \mathrm{Hg}$ , and $\mathrm{Pa}_{\mathrm{CO}_{2}}=32 \mathrm{~mm} \mathrm{Hg}$ . Which statement best explains the observed value of $\mathrm{Pa}_{\mathrm{CO}_{2}}$ ?

A) The increased $\mathrm{pH}$ stimulates breathing via peripheral chemoreceptors
B) The increased $\mathrm{pH}$ stimulates breathing via central chemoreceptors
C) The decreased $\mathrm{Pa}_{\mathrm{O}_{2}}$ inhibits breathing via peripheral chemoreceptors
D) The decreased $\mathrm{Pa}_{\mathrm{O}_{2}}$ stimulates breathing via peripheral chemoreceptors
E) The decreased $\mathrm{Pa}_{\mathrm{O}_{2}}$ stimulates breathing via central chemoreceptors

Question 25

A 38-year-old woman moves with her family from New York City (sea level) to Leadville Colorado (10,200 feet above sea level). Which of the following will occur as a result of residing at high altitude?

A) Hypoventilation
B) Arterial $\mathrm{PO}_{2}$ greater than $100 \mathrm{~mm} \mathrm{Hg}$
C) Decreased 2,3-diphosphoglycerate (DPG) concentration
D) Shift to the right of the hemoglobin $-\mathrm{O}_{2}$ dissociation curve
E) Pulmonary vasodilation
F) Hypertrophy of the left ventricle
G) Respiratory acidosis

Question 26

The $\mathrm{pH}$ of venous blood is only slightly more acidic than the $\mathrm{pH}$ of arterial blood because

A) $\mathrm{CO}_{2}$ is a weak base
B) there is no carbonic anhydrase in venous blood
C) the $\mathrm{H}^{+}$ generated from $\mathrm{CO}_{2}$ and $\mathrm{H}_{2} \mathrm{O}$ is buffered by $\mathrm{HCO}_{3}{ }^{-}$ in venous blood
D) the $\mathrm{H}^{+}$ generated from $\mathrm{CO}_{2}$ and $\mathrm{H}_{2} \mathrm{O}$ is buffered by deoxyhemoglobin in venous blood
E) oxyhemoglobin is a better buffer for $\mathrm{H}^{+}$ than is deoxyhemoglobin

Question 27

In a maximal expiration, the total volume expired is

A) tidal volume ( $\mathrm{VT})$
B) vital capacity (VC)
C) expiratory reserve volume (ERV)
D) residual volume (RV)
E) functional residual capacity (FRC)
F) inspiratory capacity
G) total lung capacity

Question 28

A person with a ventilation/perfusion (V/Q) defect has hypoxemia and is treated with supplemental $\mathrm{O}_{2}$ . The supplemental $\mathrm{O}_{2}$ will be most helpful if the person's predominant $\mathrm{V} / \mathrm{Q}$ defect is

A) dead space
B) shunt
C) high $V / Q$
D) low $\mathrm{V} / \mathrm{Q}$
E) $V / Q=0$
F) $V / Q=\infty$

Question 29

Which person would be expected to have the largest A-a gradient?

A) Person with pulmonary fibrosis
B) Person who is hypoventilating due to morphine overdose
C) Person at 12,000 feet above sea level
D) Person with normal lungs breathing $50 \%$ $\mathrm{O}_{2}$
E) Person with normal lungs breathing $100 \% \mathrm{O}_{2}$

Question 30

Which of the following sets of data would have the highest rate of $\mathrm{O}_{2}$ transfer between alveolar gas and pulmonary capillary blood?
$\begin{array}{l}\mathrm{Pl}_{\mathrm{O}_{2}} \quad \quad \quad \mathrm{Pv}_{\mathrm{O}_{2}} \quad \text { Surface Area Thickness } \\ (\mathrm{mm} \mathrm{Hg}) \quad(\mathrm{mm} \mathrm{Hg}) \text { (relative) (relative) } \\\end{array}$

A) $\begin{array}{llll}150 & \quad \quad40 & \quad \quad1 & \quad \quad \quad 1\end{array}$
B) $150 \quad \quad \quad 40 \quad \quad \quad\quad 2 \quad \quad \quad\quad 2$
C) $300 \quad \quad\quad 40 \quad \quad \quad \quad 1 \quad \quad \quad \quad 2$
D) $\begin{array}{llll}150 & \quad 80 & \quad \quad \quad 1 & \quad \quad \quad \quad 1\end{array}$
E) $190 \quad\quad 80 \quad \quad \quad \quad \quad 2 \quad \quad \quad \quad \quad 2$