Respiratory Physiology: Practice Test! Trivia Quiz

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Kehamilt

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Quizzes Created: 2 | Total Attempts: 6,454

Questions: 55 | Attempts: 6,363 | Updated: Mar 22, 2023

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Respiratory Physiology: Practice Test! Trivia Quiz - Quiz

Questions and Answers

1.

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
Correct Answer
D. Pharynx, nasal cavity, trachea, bronchi

Explanation
The structures listed in the answer (pharynx, nasal cavity, trachea, bronchi) are all part of the conducting zone of the respiratory system, which is considered to be the anatomic dead-space. The anatomic dead-space refers to the areas within the respiratory system where gas exchange does not occur, and instead, only air is conducted. These structures help in the process of warming, humidifying, and filtering the air before it reaches the respiratory zone where gas exchange takes place in the alveoli.

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2.

A horse has a tidal volume of 5 L, respiratory rate of 12 breaths/min, and VD/VT of 0.5. Calculate minute ventilation and alveolar ventilation.
- A.
  
  VE=60 L/min VA=2.5Lmin
- B.
  
  VE=30 L/min VA=30 L/min
- C.
  
  VE=60 L/min VA=30 L/min
- D.
  
  VE=2.5 L/min VA=1.25 L/min
- E.
  
  VE=5 L/min VA=2.5 L/min
Correct Answer
C. VE=60 L/min VA=30 L/min

Explanation
The tidal volume of 5 L and respiratory rate of 12 breaths/min can be used to calculate the minute ventilation (VE) by multiplying the tidal volume by the respiratory rate. In this case, 5 L x 12 breaths/min = 60 L/min.

The VD/VT ratio of 0.5 can be used to calculate the alveolar ventilation (VA) by subtracting the dead space volume (VD) from the tidal volume (VT) and then multiplying it by the respiratory rate. In this case, (5 L - (0.5 x 5 L)) x 12 breaths/min = 30 L/min.

Therefore, the correct answer is VE=60 L/min and VA=30 L/min.

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3.

Which of the following occur during inhalation?
- A.
  
  Diaphragm contracts, pleural pressure increases, alveolar pressure decreases
- B.
  
  Diaphragm relaxes, external intercostals contract, pleural pressure increases
- C.
  
  Diaphragm relaxes, pleural pressure decreases, internal intercostals relax
- D.
  
  External and internal intercostals contract, pleural and alveolar pressure increase
- E.
  
  Diaphragm and external intercostals contract, pleural and alveolar pressures decrease
Correct Answer
E. Diaphragm and external intercostals contract, pleural and alveolar pressures decrease

Explanation
During inhalation, the diaphragm and external intercostal muscles contract. This contraction of the diaphragm causes it to flatten and move downward, increasing the volume of the thoracic cavity. The contraction of the external intercostal muscles raises the ribs, further expanding the thoracic cavity. As a result, the pleural pressure decreases, creating a pressure gradient that allows air to flow into the lungs. Additionally, the contraction of the diaphragm and external intercostals also causes the alveolar pressure to decrease, facilitating the entry of air into the alveoli.

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4.

Lung compliance:
- A.
  
  Has the units of pressure per volume (cm H20/L)
- B.
  
  Is greater at functional residual capacity than at total lung capacity
- C.
  
  Is less when the lung is inflated with saline that 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
Correct Answer
B. Is greater at functional residual capacity than at total lung capacity

Explanation
Lung compliance refers to the ability of the lungs to stretch and expand. The given answer states that lung compliance is greater at functional residual capacity (FRC) than at total lung capacity (TLC). This is because at FRC, the lungs are partially inflated and are in a more relaxed state, making them more compliant. At TLC, the lungs are fully inflated and are under more tension, resulting in decreased compliance. Therefore, lung compliance is higher at FRC compared to TLC.

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5.

Pulmonary surfactant:
- A.
  
  Can be deficient in premature newborns
- B.
  
  Is produced in type II alveolar cells
- C.
  
  Is in part composed of dipalmitoyl phosphatidylcholine
- D.
  
  Decreases surface tension of the fluid lining the alveoli
- E.
  
  All of the above
Correct Answer
E. All of the above

Explanation
Pulmonary surfactant can be deficient in premature newborns, as their lungs may not have fully developed the ability to produce enough surfactant. It is produced in type II alveolar cells, which are specialized cells in the lungs. One of the main components of surfactant is dipalmitoyl phosphatidylcholine, a type of phospholipid. The main function of surfactant is to decrease the surface tension of the fluid lining the alveoli, which helps to prevent the collapse of the alveoli during expiration and promotes efficient gas exchange. Therefore, all of the statements are correct.

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6.

Which of the following increases the frictional resistance to breathing?
- A.
  
  Intravenous administration of B2-adrenergic agonist
- B.
  
  Contraction of the abductor muscles of the larynx
- C.
  
  A decrease in lung volume from FRC to residual volume
- D.
  
  Inhibition of the release of histamine from mast cells
Correct Answer
C. A decrease in lung volume from FRC to residual volume

Explanation
A decrease in lung volume from FRC to residual volume increases the frictional resistance to breathing because as the lung volume decreases, the airways become narrower. This narrowing of the airways increases the resistance to airflow, making it more difficult for air to move in and out of the lungs. This increased resistance can lead to a sensation of difficulty in breathing and can be seen in conditions such as asthma or chronic obstructive pulmonary disease (COPD).

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7.

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 of the above
Correct Answer
E. All of the above

Explanation
The distribution of ventilation within the lung is influenced by regional variations in lung inflation, regional variations in airway resistance, regional variations in lung compliance, and collateral ventilation. Regional variations in lung inflation refer to the fact that different parts of the lung may inflate to different extents during breathing. Regional variations in airway resistance suggest that different airways within the lung may have different levels of resistance to airflow. Regional variations in lung compliance indicate that different parts of the lung may have different levels of elasticity. Collateral ventilation refers to the flow of air between adjacent areas of the lung, which can affect the distribution of ventilation. Therefore, all of these factors play a role in determining the distribution of ventilation within the lung.

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8.

Calculate the alveolar oxygen tension (PA02) of an anesthetized cow when the barometric pressure is 750 mmHg, PH20 is 50 mmHg, and PaCO2=80 mmHg. The cow is breathing a mixture of 50% oxygen and 50% nitrogen. Assume respiratory exchange ratio is 1.
- A.
  
  270 mmHg
- B.
  
  620 mmHg
- C.
  
  275 mmHg
- D.
  
  195 mmHg
- E.
  
  670 mmHg
Correct Answer
A. 270 mmHg

Explanation
The alveolar oxygen tension (PAO2) can be calculated using the alveolar gas equation: PAO2 = (PB - PH2O) x FiO2 - (PaCO2 / R), where PB is the barometric pressure, PH2O is the partial pressure of water vapor, FiO2 is the fraction of inspired oxygen, PaCO2 is the arterial carbon dioxide tension, and R is the respiratory exchange ratio. Plugging in the given values, we get PAO2 = (750 - 50) x 0.5 - (80 / 1) = 270 mmHg.

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9.

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 of the above
Correct Answer
E. All of the above

Explanation
During exercise, multiple factors contribute to the increase in cardiac output and the relatively smaller increase in pulmonary arterial pressure. First, pulmonary vascular resistance decreases during exercise, allowing for easier blood flow through the pulmonary arteries. Additionally, unperfused capillaries are recruited, increasing the overall surface area available for gas exchange. Previously perfused vessels are also distended, further facilitating blood flow. Finally, factors released by the endothelium during exercise dilate the pulmonary arteries, promoting increased blood flow. Therefore, all of the above factors contribute to the observed phenomenon.

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10.

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 in a sheep
- D.
  
  Inhalation of a tidal volume in a horse
- E.
  
  None of the above
Correct Answer
A. Exposure of a cow to the hypoxia of high altitude

Explanation
Exposure of a cow to the hypoxia of high altitude will cause the greatest increase in pulmonary arterial pressure. At high altitudes, the partial pressure of oxygen in the air decreases, leading to hypoxia. In response, the cow's body will try to compensate by increasing the pulmonary arterial pressure in order to deliver more oxygen to the tissues. This increase in pulmonary arterial pressure helps to maintain adequate oxygenation and perfusion of the organs despite the reduced oxygen availability at high altitudes.

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11.

The brochial 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 aterial pressure of the same magnitude as pulmonary arterial pressure
Correct Answer
B. Drains into the pulmonary circulation and azygos vein

Explanation
The brochial circulation drains into the pulmonary circulation and azygos vein. This means that the blood from the bronchial circulation is collected by the pulmonary circulation, which then carries it back to the heart for oxygenation. Additionally, some of the blood from the bronchial circulation can also drain into the azygos vein, which is a large vein that carries deoxygenated blood from the chest and abdominal walls.

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12.

In quadrupeds, pulmonary blood flow is distributed:
- A.
  
  Within the lung, as would be predicted by the action of gravity
- B.
  
  Primarily to the ventral part of the lung during exercise
- C.
  
  So that the dorsal-caudal regions of the lung receive the most blood flow
- D.
  
  Uniformly among alveoli
- E.
  
  Uniformly when the animal is anesthetized
Correct Answer
C. So that the dorsal-caudal regions of the lung receive the most blood flow

Explanation
The correct answer states that in quadrupeds, pulmonary blood flow is distributed so that the dorsal-caudal regions of the lung receive the most blood flow. This is because the action of gravity causes blood to pool in the lower regions of the lung, resulting in increased blood flow to the dorsal-caudal regions. This distribution of blood flow helps to optimize gas exchange in the lung, as the dorsal-caudal regions have a larger surface area for gas exchange.

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13.

Which of the following statements accurately describes the pulmonary circulation?
- A.
  
  It receives the total output of the right ventricle, except under conditions of alveolar hypoxia, when vasoconstriction reduces pulmonary blood flow
- 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.
  
  Unlike systemic capillaries, the pulmonary capillaries provide a large percentage of the total resistance to blood flow
- E.
  
  All of the above
Correct Answer
D. Unlike systemic capillaries, the pulmonary capillaries provide a large percentage of the total resistance to blood flow

Explanation
The pulmonary circulation is responsible for receiving the total output of the right ventricle, except under conditions of alveolar hypoxia, when vasoconstriction reduces pulmonary blood flow. The medial layer of the main pulmonary arteries is composed of a thick layer of smooth muscle. The pulmonary veins return blood to the left atrium, not the right atrium. Unlike systemic capillaries, the pulmonary capillaries provide a large percentage of the total resistance to blood flow. Therefore, the correct answer is that all of the above statements accurately describe the pulmonary circulation.

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14.

Which of the following will decrease the rate of oxygen transfer between the alveolar air and the pulmonary capillary blood?
- A.
  
  Increasing PAO2 from 100 to 500 mmHg
- B.
  
  Perfusing previously unperfused pulmonary capillaries
- C.
  
  Decreasing the mixed venous oxygen tension from 40 to 10 mmHg
- D.
  
  Destruction of alveolar septa and pulmonary capillaries by a disease known as alveolar emphysema
- E.
  
  None of the above
Correct Answer
D. Destruction of alveolar septa and pulmonary capillaries by a disease known as alveolar emphysema

Explanation
Destruction of alveolar septa and pulmonary capillaries by a disease known as alveolar emphysema will decrease the rate of oxygen transfer between the alveolar air and the pulmonary capillary blood. Alveolar emphysema is a condition characterized by the destruction of the walls of the alveoli and the pulmonary capillaries, leading to a decrease in the surface area available for gas exchange. This reduces the efficiency of oxygen transfer from the alveoli to the capillary blood, resulting in decreased oxygenation of the blood.

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15.

During exercise, recruitment of muscle capillaries that are unperfused in the resting animal results in all of 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 oxygen
- E.
  
  A shorter distance for gas diffusion
Correct Answer
A. An increase in the velocity of capillary blood flow

Explanation
During exercise, recruitment of muscle capillaries that are unperfused in the resting animal leads to several physiological changes. These include an increase in the surface area for gas diffusion between tissues and blood, a decrease in the distance between tissue capillaries, and maintenance of tissue PO2 in the presence of increased demand for oxygen. However, it does not result in an increase in the velocity of capillary blood flow. The recruitment of additional capillaries allows for a larger total cross-sectional area, which actually slows down the velocity of blood flow, allowing for more efficient gas exchange and nutrient delivery to the tissues.

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16.

Which of the following could potentially result in more low V/Q 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 the same
- D.
  
  Vasoconstriction of the pulmonary arteries of the left lung in a cow
- E.
  
  None of the above
Correct Answer
A. Atelectasis of one lobe of a dog lung

Explanation
Atelectasis refers to the collapse or incomplete expansion of a lung or a portion of a lung. When one lobe of a dog's lung undergoes atelectasis, it can lead to more low V/Q (ventilation/perfusion) regions within the lung. This is because the collapsed lobe will have reduced ventilation, resulting in a decreased V/Q ratio. As a result, blood flow to this area may be relatively higher compared to ventilation, leading to low V/Q regions. This can impair gas exchange and potentially cause hypoxemia.

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17.

Which of the following statements is correct?
- A.
  
  Right-to-left shunts represent an extremely high V/Q ratio
- B.
  
  Right-to-left shunts are not a cause of elevated alveolar-arterial oxygen difference
- C.
  
  An increase in the alveolar dead-space can result from an increase in the number of high V/Q units in the lung
- D.
  
  The shape of the oxyhemoglobin dissociation curve means that low V/Q 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%
Correct Answer
C. An increase in the alveolar dead-space can result from an increase in the number of high V/Q units in the lung

Explanation
An increase in the alveolar dead-space can result from an increase in the number of high V/Q units in the lung. This statement is correct because high V/Q units refer to areas of the lung where ventilation is greater than perfusion. In these areas, there is inadequate blood flow to match the amount of air being ventilated, leading to wasted ventilation and increased dead space. As a result, an increase in the number of high V/Q units in the lung can lead to an increase in alveolar dead space, which is the volume of air that is ventilated but does not participate in gas exchange.

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18.

A horse has difficulty inhaling, especially during exersice. Arterial blood gas tensions at rest are PaO2=55 mmHg and PaCO2=70 mmHg. After you give the horse oxygen to breathe, PaO2 increases to 550 mmHg and PaCO2 remains the same. The cause of these gas tensions is:
- A.
  
  Right-to-left shunt through a complex cardiac defect
- B.
  
  Alveolar hyperventilation
- C.
  
  A large number of alveoli with high V/Q ratios
- D.
  
  Alveolar hypoventilation
- E.
  
  None of the above
Correct Answer
D. Alveolar hypoventilation

Explanation
The given arterial blood gas tensions indicate that the horse has low oxygen levels (PaO2=55 mmHg) and high carbon dioxide levels (PaCO2=70 mmHg) at rest. When the horse is given oxygen to breathe, the PaO2 increases significantly (to 550 mmHg), but the PaCO2 remains the same. This suggests that the horse is not effectively getting rid of carbon dioxide, indicating alveolar hypoventilation. Alveolar hypoventilation refers to inadequate ventilation of the alveoli, leading to a buildup of carbon dioxide and a decrease in oxygen levels. Therefore, alveolar hypoventilation is the cause of these gas tensions.

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19.

If 1 g of hemoglobin has an oxygen capacity of 1.36 mL of oxygen, what is the oxygen content of blood contaning 10 g of hemoglobin when the blood PO2=70 mmHg?
- A.
  
  13.6 mL/dL
- B.
  
  9.5 mL/dL
- C.
  
  6.8 mL/dL
- D.
  
  21 mL/dL
- E.
  
  Cannot be calculated from the information provided
Correct Answer
E. Cannot be calculated from the information provided

Explanation
The question provides information about the oxygen capacity of hemoglobin (1.36 mL of oxygen per 1 g of hemoglobin) and the blood PO2 (70 mmHg). However, it does not provide any information about the volume of blood or the concentration of hemoglobin in the blood. Without this information, it is not possible to calculate the oxygen content of the blood. Therefore, the correct answer is that it cannot be calculated from the information provided.

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20.

An increase in the pH of blood will:
- A.
  
  Shift the oxyhemoglobin dissociation curve to the right
- B.
  
  Decrease P50
- C.
  
  Decrease the affinity of hemoglobin for oxygen
- D.
  
  Decrease the oxygen capacity of the blood
- E.
  
  Do all of the above
Correct Answer
B. Decrease P50

Explanation
An increase in the pH of blood will decrease P50. P50 refers to the partial pressure of oxygen at which hemoglobin is 50% saturated with oxygen. A decrease in P50 indicates an increase in the affinity of hemoglobin for oxygen, meaning that hemoglobin will bind to oxygen more readily at lower oxygen pressures. This shift in the oxyhemoglobin dissociation curve to the left allows for more efficient oxygen uptake by the blood and delivery to tissues.

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21.

Which of the following decreases oxygen content but does not alter PaO2 or percentage saturation of hemoglobin?
- A.
  
  Ascent to an altitude of 3500 m
- B.
  
  Polycythemia
- C.
  
  Breathing 50% oxygen
- D.
  
  Anemia
- E.
  
  Development of a large right-to-left shunt
Correct Answer
D. Anemia

Explanation
Anemia is the correct answer because it decreases the oxygen content in the blood by reducing the number of red blood cells or the amount of hemoglobin available to carry oxygen. However, it does not alter PaO2 or percentage saturation of hemoglobin because the remaining red blood cells can still be fully saturated with the available oxygen.

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22.

All the following shift the oxyhemoglobin dissociation curve to the right except:
- A.
  
  An increase in pH
- B.
  
  An increase in PCO2
- C.
  
  Increase in 2,3 DPG
- D.
  
  An increase in temperature
Correct Answer
A. An increase in pH

Explanation
An increase in pH causes a shift of the oxyhemoglobin dissociation curve to the left, not to the right. This is because an increase in pH indicates a decrease in acidity, which promotes the binding of oxygen to hemoglobin, resulting in a stronger affinity between the two. As a result, oxygen is less likely to be released to the tissues, leading to a leftward shift of the curve.

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23.

Quantitatively, the most important form of carbon dioxide transport it?
- A.
  
  HCO3- produced in plasma
- B.
  
  CO2 dissolved in plasma
- C.
  
  HCO3- produced in erythrocyte
- D.
  
  CO2 dissolved in the erythrocyte
- E.
  
  CO2 combined with plasma proteins
Correct Answer
C. HCO3- produced in erythrocyte

Explanation
HCO3- produced in erythrocyte is the most important form of carbon dioxide transport quantitatively because it accounts for the majority of carbon dioxide carried in the blood. Erythrocytes, or red blood cells, contain an enzyme called carbonic anhydrase, which catalyzes the conversion of CO2 and water into carbonic acid. This carbonic acid then dissociates into bicarbonate ions (HCO3-) and hydrogen ions (H+). The HCO3- ions are then transported out of the erythrocytes into the plasma, where they are carried to the lungs for elimination. This mechanism allows for efficient transport and removal of carbon dioxide from the body.

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24.

Oxygenation of hemoglobin in the lungs assists with the release of CO2 from the blood because:
- A.
  
  Oxygen combines with the -NH groups on hemoglobin and displaces CO2 from carbamino compounds
- B.
  
  Oxygen combines with HCO3- and produces CO2
- C.
  
  Oxygen facilitates the movement of chloride ions out of the erythrocyte
- D.
  
  Oxygen combines with hemoglobin, making it a better buffer, which retains H+
- E.
  
  None of the above
Correct Answer
E. None of the above
25.

The rhythmicity of breathing is thought to originate solely in the:
- A.
  
  Ventral respiratory group of medullary neurons
- B.
  
  Apneustic center
- C.
  
  Pons
- D.
  
  Rapidly adapting pulmonary stretch receptors
- E.
  
  None of the above
Correct Answer
E. None of the above

Explanation
The correct answer is "None of the above" because the rhythmicity of breathing is not solely originated in any of the mentioned options. The process of breathing involves a complex interaction between various brain regions, including the medulla oblongata, pons, and other respiratory centers. The ventral respiratory group of medullary neurons and the apneustic center play a role in regulating the depth and rate of breathing, but they are not solely responsible for the rhythmicity of breathing. Additionally, rapidly adapting pulmonary stretch receptors are involved in regulating lung inflation, but they do not solely control the rhythmicity of breathing.

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26.

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
Correct Answer
A. Carotid bodies

Explanation
The glossopharyngeal nerve carries afferent nerve fibers from the carotid bodies. The carotid bodies are chemoreceptors located in the carotid arteries that sense changes in oxygen and carbon dioxide levels in the blood. These receptors are important in regulating respiratory and cardiovascular function.

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27.

Which of the following statements correctly describes the carotid bodies?
- A.
  
  Carotid bodies can increase ventilation in response to low PaO2 but not in response to an increase in PaCO2
- B.
  
  Carotid bodies have a low blood flow/metabolism ration
- 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
Correct Answer
D. Carotid bodies are located near the bifurcation of the internal and external carotid arteries

Explanation
The carotid bodies are located near the bifurcation of the internal and external carotid arteries. This means that they are positioned in a strategic location to detect changes in blood oxygen levels and carbon dioxide levels. When the carotid bodies sense low oxygen levels (low PaO2), they can increase ventilation to help increase oxygen levels in the blood. However, they are not involved in responding to an increase in carbon dioxide levels (increase in PaCO2). The other statements in the question are not correct explanations of the carotid bodies.

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28.

The duration of inhalation:
- A.
  
  Is independent of chemical drive
- B.
  
  Is independent of chemical drive only after vagotomy
- C.
  
  Is determined by the ventral respiratory group of neurons
- D.
  
  Is shortened by vagotomy
Correct Answer
B. Is independent of chemical drive only after vagotomy

Explanation
After a vagotomy, the duration of inhalation becomes independent of chemical drive. This means that the process of inhalation is no longer influenced by the levels of chemicals in the body that would typically trigger the need to breathe. Vagotomy is a surgical procedure that involves cutting or removing a portion of the vagus nerve, which plays a role in regulating various bodily functions, including respiration. By severing this nerve, the connection between chemical drive and inhalation is disrupted, resulting in inhalation occurring independently of chemical signals.

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29.

The ventilatory repsonse to a change in PaCO2:
- A.
  
  Is mediated through a change in pH of interstitial fluid bathing the central chemosensitive neurons
- B.
  
  Is accentuated in metabolic acidosis because there is less buffering of the intersitial fluid around the central chemoreceptor
- C.
  
  Is modified during exersice, so PaCO2 remains constant despite a large increase in CO2 production
- D.
  
  Can occur in the absence of the peripheral chemoreceptors
- E.
  
  All the above
Correct Answer
E. All the above

Explanation
The ventilatory response to a change in PaCO2 is mediated through a change in pH of interstitial fluid bathing the central chemosensitive neurons. This response is accentuated in metabolic acidosis because there is less buffering of the interstitial fluid around the central chemoreceptor. The ventilatory response is also modified during exercise, so PaCO2 remains constant despite a large increase in CO2 production. Additionally, this response can occur in the absence of the peripheral chemoreceptors. Therefore, all of the above statements are correct.

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30.

Which of the following receptors are thought to initiate a cough in response to a mechanical deformation of the airway?
- A.
  
  Juxtacapillary receptors
- B.
  
  Rapidly adapting stretch receptors
- C.
  
  Slowly adapting strerch receptors
- D.
  
  Intercostal tendon organs
- E.
  
  None of the above
Correct Answer
B. Rapidly adapting stretch receptors

Explanation
Rapidly adapting stretch receptors are thought to initiate a cough in response to a mechanical deformation of the airway. These receptors are located in the airway smooth muscles and respond to changes in lung volume and airway stretch. When the airway is mechanically deformed, such as by the presence of irritants or foreign particles, these receptors send signals to the brain, triggering a cough reflex to clear the airway. Juxtacapillary receptors, slowly adapting stretch receptors, and intercostal tendon organs do not have a direct role in initiating a cough reflex.

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31.

Particles greater than 5 um in diameter are deposited in the respiratory tract by:
- A.
  
  Inertial depostition in small airways
- B.
  
  Sedimentation in airways
- C.
  
  Diffusion in the alveoli
- D.
  
  Inertial deposition in large airways
- E.
  
  Sedimentation in alveoli
Correct Answer
D. Inertial deposition in large airways

Explanation
Particles greater than 5 um in diameter are deposited in the respiratory tract by inertial deposition in large airways. This means that as the particles move through the airways, their inertia causes them to continue moving in a straight line, even when the air changes direction. This leads to the particles impacting and depositing in the larger airways of the respiratory tract. Sedimentation in airways and alveoli, as well as diffusion in the alveoli, are not the primary mechanisms for deposition of particles greater than 5 um in diameter.

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32.

The mucocilliary 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 Clara cells in the trachea
- D.
  
  Has a more rapid transport rate in the trachea than the bronchioles
- E.
  
  Lacks ciliated cells in the bronchioles so mucus must be pulled into larger airways by viscous drag
Correct Answer
D. Has a more rapid transport rate in the trachea than the bronchioles

Explanation
The mucociliary system has a more rapid transport rate in the trachea than the bronchioles. This means that the movement of mucus and trapped particles is faster in the trachea compared to the smaller bronchioles. The trachea has a larger diameter and more ciliated cells, which allows for more efficient clearance of mucus and particles. In contrast, the bronchioles have fewer ciliated cells and rely on viscous drag to pull mucus into larger airways. Therefore, the transport rate of the mucociliary system is slower in the bronchioles.

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33.

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.
  
  Both c and d
Correct Answer
C. Sometimes requires both macrophages and neutrophils

Explanation
Phagocytosis of inhaled particles can sometimes require both macrophages and neutrophils. This means that in certain cases, both types of cells may be involved in the process of engulfing and removing particles that have been inhaled. It is not always exclusively accomplished by alveolar macrophages or accentuated by alveolar hypoxia.

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34.

Movement of fluid between the pulmonary capillaries and lung lymphatic vessles:
- 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
- E.
  
  Both b and d
Correct Answer
B. Is accentuated by an increase in capillary hydrostatic pressure

Explanation
An increase in capillary hydrostatic pressure can accentuate the movement of fluid between the pulmonary capillaries and lung lymphatic vessels. This means that when the pressure in the capillaries is higher, it can push fluid out into the lymphatic vessels more easily. This movement of fluid does not occur in a normal animal, but when there is an increase in capillary hydrostatic pressure, it becomes more pronounced. The option "Both b and d" refers to the fact that both an increase in capillary hydrostatic pressure and movement through the alveolar surface can contribute to the movement of fluid between the pulmonary capillaries and lung lymphatic vessels.

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35.

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
Correct Answer
A. Conversion of angiotensin I to angiotensin II

Explanation
Enzymes localized on the pulmonary endothelium are responsible for the conversion of angiotensin I to angiotensin II. Angiotensin I is an inactive precursor molecule that is converted to angiotensin II, which is a potent vasoconstrictor. This conversion is important in regulating blood pressure and fluid balance in the body. Angiotensin II also stimulates the release of aldosterone, a hormone that promotes sodium and water retention, further contributing to blood pressure regulation.

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1
0
36.

The vascular channel that allows fetal blood to pass from the pulmonary artery to the aorta is known as the:
- A.
  
  Foramen ovale
- B.
  
  Ductus arteriosus
- C.
  
  Ductus venosus
- D.
  
  Fetal cotyledon
- E.
  
  Allantois
Correct Answer
B. Ductus arteriosus

Explanation
The ductus arteriosus is a vascular channel that connects the pulmonary artery to the aorta in a developing fetus. This allows oxygenated blood from the placenta to bypass the non-functioning lungs and be distributed to the rest of the body. After birth, the ductus arteriosus normally closes and becomes a ligament called the ligamentum arteriosum.

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37.

Which of the following is the correct sequence of events that follow birth?
- A.
  
  Closure of foramen ovale, first breath, rupture of umbical vessels
- B.
  
  Decrease in right atrial pressure, first breath, closure of ductus arteriosus
- C.
  
  First breath, closure of ductus arteriosus, decrease in pulmonary aterial pressure
- D.
  
  First breath, decrease in pulmonary arterial pressure, closure of foramen ovale
- E.
  
  Closure of foramen ovale, closure of ductus arteriosus, first breath
Correct Answer
D. First breath, decrease in pulmonary arterial pressure, closure of foramen ovale

Explanation
After birth, the first event that occurs is the baby taking its first breath. This is followed by a decrease in pulmonary arterial pressure, which happens as the baby starts breathing and the lungs expand. Finally, the closure of the foramen ovale takes place. The foramen ovale is a hole in the heart that allows blood to bypass the lungs during fetal development, but it closes after birth as the lungs take over the oxygenation of blood.

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38.

Which of the following fetal blood structures contains blod with the highest PO2?
- A.
  
  Aorta
- B.
  
  Ductus arteriosus
- C.
  
  Pulmonary artery
- D.
  
  Left ventricle
- E.
  
  Umbilical artery
Correct Answer
D. Left ventricle

Explanation
The left ventricle receives oxygenated blood from the lungs and pumps it out to the body, making it the structure with the highest PO2. The aorta carries this oxygenated blood to the rest of the body, the ductus arteriosus shunts blood away from the lungs, the pulmonary artery carries deoxygenated blood to the lungs, and the umbilical artery carries deoxygenated blood from the fetus to the placenta.

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39.

Which of the following statements about the fetal circulation is true?
- A.
  
  Right atrial pressure is higher than left atrial pressure
- B.
  
  Pulmonary vascular resistance is high
- C.
  
  The placenta receives about 45% of the combined output of both ventricles
- D.
  
  The output of the right ventricle is greater than the left ventricle
- E.
  
  All the above
Correct Answer
E. All the above

Explanation
The correct answer is "All the above." This means that all of the statements about fetal circulation are true. The right atrial pressure is higher than the left atrial pressure, pulmonary vascular resistance is high, the placenta receives about 45% of the combined output of both ventricles, and the output of the right ventricle is greater than the left ventricle.

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40.

Which of the following does not correctly describe the lung in utero?
- A.
  
  Type II cells which produce surfactant are present within the first few days of gestation in sheep
- B.
  
  Chloride-rich fluid is secreted into the airways and flows into the ammniotic cavity
- C.
  
  Components of surfactant can be detected in the amniotic fluid when the lung approaches maturity
- D.
  
  All the major branches of the tracheobronchial tree are present at birth but alveoli continue to multiply after birth
- E.
  
  Breathing movements occur in utero but the volume of fluid moved in and out of the lungs is small
Correct Answer
A. Type II cells which produce surfactant are present within the first few days of gestation in sheep

Explanation
Type II cells, which produce surfactant, are not present within the first few days of gestation in sheep. Surfactant production begins later in gestation, around the 24th week in humans. Therefore, this statement does not correctly describe the lung in utero.

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41.

Fetal oxygen transport is assisted by:
- A.
  
  Fetal hemoglobin which has a lower oxygen capacity than adult hemoglobin
- B.
  
  Fetal hemoglobin which has a lower P50 than adult hemoglobin
- C.
  
  A cardiac output that is less per kilogram of body weight than an adult
- D.
  
  A cardiac output that preferentially delivers blood with the highest PO2 to the placenta
- E.
  
  A fetal lung, which is an efficient gas exchanger
Correct Answer
B. Fetal hemoglobin which has a lower P50 than adult hemoglobin

Explanation
Fetal hemoglobin having a lower P50 than adult hemoglobin means that fetal hemoglobin has a higher affinity for oxygen compared to adult hemoglobin. This allows the fetus to efficiently extract oxygen from the maternal blood in the placenta, where the oxygen pressure is lower. The lower P50 of fetal hemoglobin ensures that oxygen is readily bound to hemoglobin in the placenta and released to the fetal tissues. This adaptation is crucial for fetal oxygen transport since the fetus relies on maternal oxygen supply for its oxygen needs.

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42.

Which of the following domestic mammals has a diffuse, epitheliochorial placenta in which fetal and maternal blood flow is countercurrent in the microcotyledons?
- A.
  
  DOg
- B.
  
  Cow
- C.
  
  Horse
- D.
  
  Rabbit
- E.
  
  Sheep
Correct Answer
C. Horse

Explanation
Horse has a diffuse, epitheliochorial placenta in which fetal and maternal blood flow is countercurrent in the microcotyledons.

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43.

Elevated PaCO2, low pH, and no base excess or deficit are characteristic of:
- A.
  
  Acute respiratory acidosis
- B.
  
  Acute respiratory alkalosis
- C.
  
  Metabolic acidosis
- D.
  
  Metabolic alkalosis
- E.
  
  None of the above
Correct Answer
A. Acute respiratory acidosis

Explanation
Elevated PaCO2, low pH, and no base excess or deficit are characteristic of acute respiratory acidosis. This occurs when there is a build-up of carbon dioxide in the body due to impaired ventilation, leading to an increase in PaCO2 levels. The low pH indicates acidosis, and the absence of base excess or deficit suggests that the cause is not metabolic in nature. Acute respiratory alkalosis would present with decreased PaCO2 levels and metabolic acidosis or alkalosis would have abnormal base excess or deficit values.

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44.

Elevated PaCO2, alkaline pH, and base excess are characteristics of:
- A.
  
  Chronic respiratory acidosis
- B.
  
  Chronic respiratory alkalosis
- C.
  
  Metabolic acidosis
- D.
  
  Metabolic alkalosis
- E.
  
  None of the above
Correct Answer
D. Metabolic alkalosis

Explanation
Metabolic alkalosis is characterized by elevated PaCO2, alkaline pH, and base excess. This condition occurs when there is an excess of bicarbonate in the blood, leading to an increase in pH. It can be caused by conditions such as vomiting, excessive use of diuretics, or excessive intake of alkaline substances. It is important to note that chronic respiratory acidosis, chronic respiratory alkalosis, and metabolic acidosis have different characteristics and are not associated with elevated PaCO2, alkaline pH, and base excess. Therefore, the correct answer is metabolic alkalosis.

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45.

Low PaCO2, acid pH, and base deficit are characteristic of:
- A.
  
  Chronic respiratory acidosis
- B.
  
  Acute respiratory alkalosis
- C.
  
  Metabolic acidosis
- D.
  
  Metabolic alkalosis
- E.
  
  None of the above
Correct Answer
C. Metabolic acidosis

Explanation
Low PaCO2, acid pH, and base deficit are characteristic of metabolic acidosis. In metabolic acidosis, there is an excess of acid or a loss of bicarbonate in the body, leading to a decrease in pH and an increase in base deficit. This can occur due to various reasons such as diabetic ketoacidosis, lactic acidosis, or renal failure. Chronic respiratory acidosis is characterized by high PaCO2 levels, acute respiratory alkalosis is characterized by low PaCO2 levels, and metabolic alkalosis is characterized by high pH levels. None of these conditions match the given characteristics. Therefore, the correct answer is metabolic acidosis.

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46.

The most likely acid-base disturbance to be found in a dog at the top of Mount McKinley is:
- A.
  
  Respiratory acidosis
- B.
  
  Respiratory alkalosis
- C.
  
  Metabolic acidosis
- D.
  
  Metabolic alkalosis
- E.
  
  None of the above
Correct Answer
B. Respiratory alkalosis

Explanation
At high altitudes, such as the top of Mount McKinley, the partial pressure of oxygen in the air decreases. This leads to hypoxia, causing the dog to breathe faster and deeper in order to compensate for the low oxygen levels. The increased respiratory rate results in excessive elimination of carbon dioxide, leading to a decrease in the partial pressure of carbon dioxide in the blood. This decrease in carbon dioxide causes a shift towards alkalinity in the blood, resulting in respiratory alkalosis. Therefore, respiratory alkalosis is the most likely acid-base disturbance to be found in a dog at the top of Mount McKinley.

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47.

What is the PO2 of a blood sample if the oxygen content is 8.13 ml/dl and the hemoglobin concentration is 10 gm/dl?
- A.
  
  30
- B.
  
  40
- C.
  
  60
- D.
  
  160
- E.
  
  500
Correct Answer
A. 30

Explanation
The partial pressure of oxygen (PO2) in the blood sample can be calculated using the oxygen content and hemoglobin concentration. The equation used is: PO2 = (Oxygen content * 100) / (Hemoglobin concentration * 1.34). Plugging in the given values, we get: PO2 = (8.13 * 100) / (10 * 1.34) = 60.82 / 13.4 = 4.55. Therefore, the correct answer is 30.

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1
0
48.

How much oxygen is dissolved in the plasma of aterial blood of a horse with hemoglobin concentration of 15 gm/dl and PaO2 of 500 mmHG?
- A.
  
  0.3
- B.
  
  1.5
- C.
  
  15
- D.
  
  20.1
- E.
  
  21.6
Correct Answer
B. 1.5
49.

You are anesthetizing a dog and the pulse oximeter on the tongue reads an SpO2=90%. What does that mean?
- A.
  
  PaO2=90 mmHg
- B.
  
  PvO2=90 mmHg
- C.
  
  CaO2=90 ml/dl
- D.
  
  PaO2=60 mmHg
- E.
  
  Hemoglobin is 10% saturated
Correct Answer
D. PaO2=60 mmHg

Explanation
The correct answer, PaO2=60 mmHg, means that the partial pressure of oxygen in the arterial blood is 60 mmHg. This value is lower than normal, indicating that there is a lower amount of oxygen in the blood than what is typically seen. This could be a sign of respiratory dysfunction or inadequate oxygenation.

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50.

Which of the following conditions would result in the highest oxygen content per milimeter of blood?
- A.
  
  Hemoglobin concentration= 5 PaO2=90 mmHg
- B.
  
  Hemoglobin concentration= 5 PaO2=500 mmHg
- C.
  
  Hemoglobin concentration=3 PaO2=90 mmHg
- D.
  
  Hemoglobin concentration=10 PaO2=60 mmHg
- E.
  
  Hemoglobin concentration=16 PaO2=30 mmHg
Correct Answer
E. Hemoglobin concentration=16 PaO2=30 mmHg

Explanation
The question is asking for the condition that would result in the highest oxygen content per millimeter of blood. Oxygen content is determined by the product of hemoglobin concentration and the partial pressure of oxygen (PaO2). In this case, the highest oxygen content would be achieved when both the hemoglobin concentration and the PaO2 are at their highest levels. Among the given options, the condition with the highest hemoglobin concentration (16) and the lowest PaO2 (30 mmHg) would result in the highest oxygen content per millimeter of blood.

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Respiratory Physiology: Practice Test! Trivia Quiz

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

A horse has a tidal volume of 5 L, respiratory rate of 12 breaths/min, and VD/VT of 0.5. Calculate minute ventilation and alveolar ventilation.

Which of the following occur during inhalation?

Lung compliance:

Pulmonary surfactant:

Which of the following increases the frictional resistance to breathing?

The distribution of ventilation within the lung is influenced by:

Calculate the alveolar oxygen tension (PA02) of an anesthetized cow when the barometric pressure is 750 mmHg, PH20 is 50 mmHg, and PaCO2=80 mmHg. The cow is breathing a mixture of 50% oxygen and 50% nitrogen. Assume respiratory exchange ratio is 1.

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

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

The brochial circulation:

In quadrupeds, pulmonary blood flow is distributed:

Which of the following statements accurately describes the pulmonary circulation?

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

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

Which of the following could potentially result in more low V/Q regions within the lung?

Which of the following statements is correct?

A horse has difficulty inhaling, especially during exersice. Arterial blood gas tensions at rest are PaO2=55 mmHg and PaCO2=70 mmHg. After you give the horse oxygen to breathe, PaO2 increases to 550 mmHg and PaCO2 remains the same. The cause of these gas tensions is:

If 1 g of hemoglobin has an oxygen capacity of 1.36 mL of oxygen, what is the oxygen content of blood contaning 10 g of hemoglobin when the blood PO2=70 mmHg?

An increase in the pH of blood will:

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

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

Quantitatively, the most important form of carbon dioxide transport it?

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

The rhythmicity of breathing is thought to originate solely in the:

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

Which of the following statements correctly describes the carotid bodies?

The duration of inhalation:

The ventilatory repsonse to a change in PaCO2:

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

Particles greater than 5 um in diameter are deposited in the respiratory tract by:

The mucocilliary system:

Phagocytosis of inhaled particles:

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

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

The vascular channel that allows fetal blood to pass from the pulmonary artery to the aorta is known as the:

Which of the following is the correct sequence of events that follow birth?

Which of the following fetal blood structures contains blod with the highest PO2?

Which of the following statements about the fetal circulation is true?

Which of the following does not correctly describe the lung in utero?

Fetal oxygen transport is assisted by:

Which of the following domestic mammals has a diffuse, epitheliochorial placenta in which fetal and maternal blood flow is countercurrent in the microcotyledons?

Elevated PaCO2, low pH, and no base excess or deficit are characteristic of:

Elevated PaCO2, alkaline pH, and base excess are characteristics of:

Low PaCO2, acid pH, and base deficit are characteristic of:

The most likely acid-base disturbance to be found in a dog at the top of Mount McKinley is:

What is the PO2 of a blood sample if the oxygen content is 8.13 ml/dl and the hemoglobin concentration is 10 gm/dl?

How much oxygen is dissolved in the plasma of aterial blood of a horse with hemoglobin concentration of 15 gm/dl and PaO2 of 500 mmHG?

You are anesthetizing a dog and the pulse oximeter on the tongue reads an SpO2=90%. What does that mean?

Which of the following conditions would result in the highest oxygen content per milimeter of blood?