Section VIII: Respiratory Function

Question 1

Chapter 45 Overview of Respiratory Function:

Ventilation of the Lungs

Which of the following is true?

a. O2 consumption per kilogram body weight is greater in a 50-g mammal than in a 50-kg mammal.
b. Maximal O2 consumption in mammals is directly related to the volume of mitochondria in the skeletal muscles.
c. O2 consumption increases when metabolic rate increases.
d. O2 consumption can increase up to thirtyfold during intense exercise.
e. All of the above are true.

Answer 1

E

Question 2

Functional residual capacity is:

a. The volume of air remaining in the lung at the end of a maximal forced exhalation.
b. The mechanical equilibrium of the respiratory system.
c. Less than residual volume.
d. Greater than total lung capacity.
e. Determined by metabolic rate.

Answer 2

B

Question 3

Which of the following lists includes only structures that compose the anatomic dead space?

a. Respiratory bronchioles, alveoli, trachea, nasal cavity
b. Pharynx, bronchi, alveolar ducts, larynx
c. Capillaries, respiratory bronchioles, trachea, bronchi
d. Pharynx, nasal cavity, trachea, bronchi
e. Capillaries, respiratory bronchioles, alveolar ducts, alveoli

Answer 3

D

Question 4

A horse has a tidal volume (VT) of 5 L, respiratory rate of 12 breaths/min, and VD/VT ratio of 0.5. Calculate minute ventilation (V̇E) and alveolar ventilation (V̇
A).
a. V̇E = 60 L/min; V̇A = 2.5 L/min
b. V̇E = 30 L/min; V̇A = 30 L/min
c. V̇E = 60 L/min; V̇A = 30 L/min
d. V̇E = 2.5 L/min; V̇A = 1.25 L/min
e. V̇E = 5.0 L/min; V̇A = 2.5 L/min

Answer 4

C

Question 5

Which of the following occur during inhalation?

a. Diaphragm contracts, pleural pressure increases, alveolar pressure decreases.
b. Diaphragm relaxes, external intercostal muscles contract, pleural pressure increases.
c. Diaphragm relaxes, pleural pressure decreases, internal intercostal muscles relax.
d. External and internal intercostal muscles contract, pleural and alveolar pressures increase.
e. Diaphragm and external intercostal muscles contract, pleural and alveolar pressures decrease

Answer 5

E

Question 6

Lung compliance:

a. Has the units of pressure per volume (cm H2O/L).
b. Is greater at functional residual capacity (FRC) than at total lung capacity (TLC).
c. Is less when the lung is inflated with saline than when the lung is inflated with air.
d. Is greater in small mammals than in large mammals, even when adjusted for differences in lung size.
e. Is the only determinant of the change in pleural pressure during breathing

Answer 6

B

Question 7

Pulmonary surfactant:

a. Can be deficient in premature newborns.
b. Is produced in type II alveolar epithelial cells.
c. Is in part composed of dipalmitoyl phosphatidylcholine.
d. Decreases surface tension of the fluid lining the alveoli.
e. All the above.

Answer 7

E

Question 8

Which of the following increases the frictional resistance to breathing?

a. Intravenous administration of a β2-adrenergic agonist
b. Contraction of the abductor muscles of the larynx
c. A decrease in lung volume from FRC to residual volume
d. Relaxation of the trachealis muscle
e. Inhibition of the release of histamine from mast cells

Answer 8

C

Question 9

The distribution of ventilation within the lung is influenced by:

a. Regional variations in lung inflation.
b. Regional variations in airway resistance.
c. Regional variations in lung compliance.
d. Collateral ventilation.
e. All the above.

Answer 9

E

Question 10

Chapter 46 Blood Flow Through the Lungs

Which of the following statements accurately describes the pulmonary circulation?

a. Pulmonary arteries carry oxygenated blood from the right ventricle to the alveolar capillaries.
b. The medial layer of the main pulmonary arteries is composed of a thick layer of smooth muscle.
c. The pulmonary veins return blood to the right atrium.
d. The pulmonary circulation receives the total output of the right ventricle.
e. All the above.

Answer 10

D

Question 11

During exercise, cardiac output can increase fivefold, but pulmonary arterial pressure may not even double. This occurs because:

a. Pulmonary vascular resistance decreases during exercise.
b. Unperfused capillaries are recruited during exercise.
c. Previously perfused vessels are distended during exercise.
d. Factors that dilate the pulmonary arteries are released by
the endothelium during exercise.
e. All the above

Answer 11

E

Question 12

Which of the following will cause the greatest increase in pulmonary arterial pressure?

a. Exposure of a cow to the hypoxia of high altitude
b. A twofold increase in pulmonary blood flow
c. Stimulation of the vagus nerve (parasympathetic system) in a sheep
d. Inhalation of a tidal volume in a horse
e. None of the above

Answer 12

A

Question 13

The bronchial circulation:

a. Receives the total output of the right ventricle.
b. Drains into the pulmonary circulation and azygos vein.
c. Vasoconstricts in response to hypoxia.
d. Supplies nutrient blood flow only to bronchi and no other
structures.
e. Has a bronchial arterial pressure of the same magnitude as pulmonary arterial pressure.

Answer 13

B

Question 14

Pulmonary vascular resistance (PVR) is calculated as:
a. PVR = (right ventricle pressure – left ventricle pressure)/cardiac output
b. PVR = (aortic pressure – right atrial pressure)/cardiac output
c. PVR = (pulmonary artery pressure – left atrial pressure)/cardiac output
d. PVR = (left atrial pressure – pulmonary venous pressure)/cardiac output
e. None of the above

Answer 14

C

Question 15

Chapter 47 Gas Exchange

Calculate the PAO2 of an anesthetized cow when the atmospheric pressure is 750 mm Hg, PH2O at body temperature = 50 mm Hg, and PaCO2 = 80 mm Hg. The cow is breathing a mixture of 50% O2 and 50% nitrogen. Assume the respiratory exchange ratio is 0.8.

a. 250 mm Hg
b. 620 mm Hg
c. 275 mm Hg
d. 195 mm Hg
e. 670 mm Hg

Answer 15

A

Question 16

Which of the following will decrease the rate of O2 transfer between the alveolar air and the pulmonary capillary blood?

a. Increasing PAO2 from 100 to 500 mm Hg
b. Perfusing previously unperfused pulmonary capillaries
c. Decreasing the PvO2 from 40 to 10 mm Hg
d. Destruction of alveolar septa and pulmonary capillaries by a disease known as alveolar emphysema
e. None of the above

Answer 16

D

Question 17

During exercise, recruitment of muscle capillaries that are unperfused in the resting animal results in all the following
except:

a. An increase in the velocity of capillary blood flow.
b. An increase in the surface area for gas diffusion between tissues and blood.
c. A decrease in distance between tissue capillaries.
d. Maintenance of tissue PO2 in the presence of increased demand for O2.
e. A shorter distance for gas diffusion

Answer 17

A

Question 18

Which of the following could potentially result in more low V̇ A/Q̇ regions within the lung?

a. Atelectasis of one lobe of a dog lung
b. Obstruction of both pulmonary arteries
c. Doubling the ventilation to the right cranial lobe while its blood flow remains constant
d. Vasoconstriction of the pulmonary arteries of the left lung in a cow
e. None of the above

Answer 18

A

Question 19

Which of the following statements is correct?

a. Right-to-left shunts represent an extremely high V̇ A/Q̇ ratio.
b. Right-to-left shunts are not a cause of elevated A-aDO2.
c. An increase in the alveolar dead space can result from an increase in the number of high V̇ A/Q̇ units in the lung.
d. The shape of the oxyhemoglobin dissociation curve means that low V̇ A/Q̇ units in the lung are not a cause of hypoxemia (low PaO2).
e. Totally occluding the right pulmonary artery increases the right-to-left shunt fraction by 50%.

Answer 19

C

Question 20

A horse has difficulty inhaling, especially during exercise. Arterial blood gas partial pressures at rest are PaO2 = 55 mm Hg and PaCO2 = 70 mm Hg. After you give the horse O2 to breathe, PaO2 increases to 550 mm Hg, and PaCO2 remains unchanged. The cause of these gas partial pressures is:

a. Right-to-left shunt through a complex cardiac defect.
b. Alveolar hyperventilation.
c. A large number of alveoli with high V̇ A/Q̇ ratios.
d. Alveolar hypoventilation.
e. None of the above.

Answer 20

D

Question 21

Chapter 48 Gas Transport in the Blood

If 1 g of hemoglobin has an O2 capacity of 1.36 mL of O2, what is the O2 content of blood containing 10 g of hemoglobin
when the blood PO2 is 70 mm Hg?

a. 13.6 mL O2/dL blood
b. 9.5 mL O2/dL blood
c. 6.8 mL O2/dL blood
d. 21 mL O2/dL blood
e. Cannot be calculated from the information provided

Answer 21

E

Question 22

An increase in pH of blood will:

a. Shift the oxyhemoglobin dissociation curve to the right.
b. Decrease P50.
c. Decrease the affinity of hemoglobin for O2.
d. Decrease the O2 capacity of the blood.
e. All the above

Answer 22

B

Question 23

Which of the following decreases O2 content but does not alter PaO2 or percentage saturation of hemoglobin?

a. Ascent to an altitude of 3500 m
b. Polycythemia
c. Breathing 50% O2
d. Anemia
e. Development of a large right-to-left shunt

Answer 23

D

Question 24

All the following shift the oxyhemoglobin dissociation curve to the right except:

a. An increase in pH
b. An increase in PCO2
c. An increase in 2,3-BPG
d. An increase in temperature

Answer 24

A

Question 25

Quantitatively, the most important form of CO2 in blood is:

a. HCO3−produced in plasma
b. CO2 dissolved in plasma
c. HCO3−produced in the erythrocyte
d. CO2 dissolved in the erythrocyte
e. CO2 combined with plasma proteins

Answer 25

C

Question 26

Oxygenation of hemoglobin in the lungs assists with the release of CO2 from the blood because:

a. O2 combines with the –NH groups on hemoglobin and displaces CO2 from carbamino compounds.
b. O2 combines with HCO3− and produces CO2.
c. O2 facilitates the movement of chloride ions out of the erythrocyte.
d. O2 combines with hemoglobin, making it a better buffer, which retains H+.
e. None of the above.

Answer 26

E

Question 27

Chapter 49 Control of Ventilation

The rhythmicity of breathing is thought to originate in:

a. The carotid body
b. The central pattern generator
c. The central chemoreceptor
d. Rapidly adapting pulmonary stretch receptors
e. None of the above

Answer 27

B

Question 28

Which of the following receptors have afferent nerve fibers in the glossopharyngeal nerve?

a. Carotid bodies
b. Slowly adapting pulmonary stretch receptors
c. Aortic bodies
d. Intercostal stretch receptors
e. Rapidly adapting pulmonary stretch receptors

Answer 28

A

Question 29

Which of the following statements correctly describes the carotid bodies?

a. Carotid bodies can increase ventilation in response to low PO2, but not in response to an increase in PCO2.
b. Carotid bodies have a low blood flow/metabolism ratio.
c. Chemoreception is thought to occur in the sustentacular cells.
d. Carotid bodies are located near the bifurcation of the internal and external carotid arteries.
e. All the above.

Answer 29

D

Question 30

The retrotrapezoidal neurons:

a. Are highly sensitive to increases in hydrogen ion concentration.
b. Receive inputs from the carotid body via the nucleus tractus solitarius.
c. Provide input to the central pattern generator.
d. Receive inputs from higher centers such as the hypothalamus.
e. Are described by all of the above.

Answer 30

A

Question 31

Which of the following is correct concerning the role of PaCO2 in breathing?

a. PaCO2 exerts its effects on ventilation by changing the pH of brain interstitial fluid.
b. PaCO2 has no effect on the carotid body.
c. PaCO2 remains constant when hypoxemia increases ventilation during the ascent to high altitude.
d. PaCO2 is much less important than PaO2 in regulation of breathing.
e. None of the above

Answer 31

A

Question 32

Which of the following receptors are thought to initiate a cough in response to mechanical deformation of the airway?

a. Juxtacapillary receptors
b. Rapidly adapting stretch receptors
c. Slowly adapting stretch receptors
d. Intercostal tendon organs
e. None of the above

Answer 32

B

Question 33

Chapter 50 Nonrespiratory Functions of the Lungs

Particles greater than 5 µm in diameter are deposited in the respiratory tract by:
a. Inertial deposition in small airways.
b. Sedimentation in airways.
c. Diffusion in the alveoli.
d. Inertial deposition in large airways.
e. Sedimentation in the alveoli.

Answer 33

D

Question 34

The mucociliary system:

a. Consists of a gel layer in which cilia beat, overlaid by a sol layer that entraps particles.
b. Is restricted to the nasal cavity and trachea and does not extend into the bronchi.
c. Consists in part of mucus produced by goblet cells in the respiratory bronchioles and by club cells in the trachea.
d. Has a more rapid transport rate in the trachea than in the bronchioles.

Answer 34

D

Question 35

Phagocytosis of inhaled particles:

a. Is generally by type II alveolar cells.
b. Can always be accomplished by alveolar macrophages.
c. Sometimes requires both macrophages and neutrophils.
d. Is accentuated by alveolar hypoxia.
e. None of the above.

Answer 35

C

Question 36

Movement of fluid between the pulmonary capillaries and lung
lymphatic vessels:

a. Does not occur in a normal animal.
b. Is accentuated by an increase in capillary hydrostatic pressure.
c. Is accentuated by an increase in capillary oncotic pressure.
d. Occurs by way of the alveolar surface.

Answer 36

B

Question 37

Which of the following occurs as a result of enzymes localized on the pulmonary endothelium?

a. Conversion of angiotensin I to angiotensin II
b. Conversion of angiotensinogen to angiotensin I
c. Release of renin
d. Conversion of renin to angiotensin II
e. None of the above

Answer 37

A