Question 1

Which is TRUE about the pleural sac?

Accepted Answer

The pleural sac is a closed sac around each lung that contains a tiny volume of lubricating fluid, which reduces friction during breathing. Option A is incorrect because the pleural sac is not connected to the atmosphere. Option C is incorrect because surfactant is found inside the lungs, not the pleural sac. Option D is incorrect because the pleural sac is not air-filled; instead, it contains a small volume of pleural fluid. Option E is incorrect because although the pleural membranes are thin, they are not involved in gas exchange.

Question 2

Which of these causes inhalation/inspiration?

Accepted Answer

Inhalation/inspiration is caused by the flattening (downward movement) of the diaphragm. This causes the volume of the thoracic cavity to increase, thereby decreasing intra-alveolar pressure below atmospheric pressure and allowing air to flow into the lungs.

Question 3

During a physical examination,Joe learns that his resting tidal volume is 550 mL;his average resting respiratory rate is 15 breaths per minute;his total lung capacity is 6,000 mL;and his anatomic dead space is 150 mL.Joe's resting alveolar ventilation is

Accepted Answer

B

Question 4

Under what condition is lung compliance increased?

Accepted Answer

Emphysema increases lung compliance because it involves the destruction of alveolar walls, leading to larger but fewer alveoli. This reduces the elastic recoil of the lungs, making them more compliant or easier to inflate.

Question 5

Which of the following drugs,administered as an aerosol spray,would be most likely to help a patient during an asthmatic attack?

Accepted Answer

A β₂-adrenergic agonist would be the best choice for treating an asthmatic attack as it causes bronchodilation, which opens up the airways and improves breathing. The other options (pulmonary surfactant, muscarinic agonist, histamine, and β₂-adrenergic antagonist) would not have the same effect and would not be as effective in treating an asthmatic attack.

Question 6

Which of the following is most responsible for keeping the lung surface and the thoracic wall from separating?

Accepted Answer

Subatmospheric intrapleural pressure is responsible for keeping the lung surface and the thoracic wall from separating. This pressure is lower than both the pressure in the alveolar space and the atmospheric pressure, which creates a suction effect that keeps the lungs inflated and attached to the thoracic wall.

Question 7

Which of the following statements about the response of arteriolar smooth muscle to changing oxygen partial pressures is TRUE?

Accepted Answer

Systemic arterioles respond to a decrease in PO₂ by dilating to increase blood flow and deliver more oxygen to tissues. However, pulmonary arterioles constrict in response to a decrease in PO₂ to redirect blood flow to areas of the lung that are better ventilated, a process called hypoxic pulmonary vasoconstriction. This helps to optimize ventilation-perfusion matching in the lung, ensuring that blood flow is preferentially directed to areas with higher oxygen levels.

Question 8

Under normal circumstances,which of the following would result from an increase in transpulmonary pressure?

Accepted Answer

An increase in transpulmonary pressure would cause the lungs to expand, which would result in inhalation/inspiration. Transpulmonary pressure is the difference between the intrapulmonary pressure and the intrapleural pressure. When the intrapulmonary pressure is lower than the intrapleural pressure, air flows into the lungs causing inhalation/inspiration. Conversely, when the intrapulmonary pressure is higher than the intrapleural pressure, air flows out of the lungs causing exhalation/expiration.

Question 9

Which is normally TRUE about the intrapleural pressure?

Accepted Answer

During normal breathing, intrapleural pressure is always negative and lower than alveolar pressure. This negative pressure helps to keep the airways and alveoli open. Option B is incorrect as intrapleural pressure at functional residual capacity is between -5 and -10 mmHg below atmospheric pressure. Option C is incorrect as intrapleural pressure doesn't alternate during normal breathing. Option D is incorrect as intrapleural pressure decreases to a value lower than atmospheric pressure during a passive exhale. Option E is incorrect as intrapleural pressure is not always the same as atmospheric pressure during a passive exhale.

Question 10

Which of the following is NOT a function of the respiratory system?

Accepted Answer

The primary function of the respiratory system is the exchange of gases, where oxygen is taken in from the air and carbon dioxide is expelled. It does not take up carbon dioxide from the air to remove oxygen from the blood; rather, it does the opposite.

Question 11

What is one function of the type II alveolar cells?

Accepted Answer

Type II alveolar cells are responsible for the production and secretion of surfactant, a substance that helps reduce surface tension in the alveoli and prevents their collapse during exhalation.

Question 12

Which of the following is TRUE during the initial stage of an asthma attack?

Accepted Answer

During the initial stage of an asthma attack, the resistance to airflow (R) is increased due to bronchoconstriction and inflammation of the airways. This increased resistance leads to difficulty in breathing and other symptoms of asthma. ΔP (pressure difference) may or may not be changed during the initial stage. The flow rate may be affected depending on the degree of R and ΔP changes, but it cannot be concluded that it remains unchanged during an asthma attack.

Question 13

During a yoga class you take a deep breath,then relax and let the breath out slowly.During that exhalation,which would NOT be true?

Accepted Answer

During exhalation, the intrapleural pressure becomes more negative, not greater than alveolar pressure. Option A is incorrect because alveolar pressure is greater than atmospheric pressure during exhalation. Option C is incorrect because intrapleural pressure becomes more negative. Options D and E are correct because the diaphragm relaxes during exhalation and lung volume decreases.

Question 14

When lying down,a subject's respiratory rate is 12 breaths per minute,his anatomical dead space is 150 mL,and his minute ventilation is 7 L/min.Which of these is closest to his alveolar ventilation in liters per minute?

Accepted Answer

Alveolar ventilation = (tidal volume - anatomical dead space) x respiratory rate
Tidal volume = Minute ventilation / respiratory rate = 7 L/min / 12 breaths per minute = 0.583 L/breath.
Alveolar ventilation = (0.583 L/breath - 0.15 L/breath) x 12 breaths per minute = 5.196 L/min, which is closest to choice B (5.2).

Question 15

Which structure is NOT part of the "anatomical dead space"?

Accepted Answer

The anatomical dead space refers to the airways of the respiratory system that are not involved in gas exchange. This includes the trachea, bronchi, bronchioles, and terminal bronchioles. The respiratory bronchioles, however, are considered part of the respiratory zone where gas exchange occurs.

Question 16

Which of the following is a cause of asthma?

Accepted Answer

Inflammation of the bronchioles is a major cause of asthma. It causes narrowing of the airways leading to difficulty breathing, wheezing and coughing. Other factors like air pollution, allergens, and genetics can also contribute to the development of asthma.

Question 17

Type II alveolar cells are among the last cells to mature during fetal development.In babies born prematurely,type II alveolar cells are often not ready to perform their function.Which of the following would be TRUE of these babies?

Accepted Answer

Type II alveolar cells produce surfactant, which reduces surface tension in the alveoli and prevents them from collapsing. In babies born prematurely, type II alveolar cells may not have sufficiently produced surfactant, leading to an increased risk of alveolar collapse due to too much surface tension.

Question 18

Type II alveolar cells are among the last cells to mature during fetal development.In babies born prematurely,type II alveolar cells are often not ready to perform their functions.Which of the following drugs would be most likely to help an infant with immature type II alveolar cells?

Accepted Answer

Pulmonary surfactant helps in reducing surface tension in the alveoli, which is necessary for efficient gas exchange. Premature infants with immature type II alveolar cells often do not produce enough pulmonary surfactant, leading to respiratory distress syndrome. Administering exogenous pulmonary surfactant can help improve lung function in these infants. Beta-adrenergic agonists, muscarinic agonists, and histamine are not directly related to surfactant production and may not be effective in treating this condition. Beta-adrenergic antagonists can actually worsen respiratory distress by decreasing bronchodilation.

Question 19

The volume of air flowing into the alveoli during inhalation/inspiration is increased when there is an increase in which of these?

Accepted Answer

The volume of air flowing into the alveoli during inhalation/inspiration is directly proportional to the pressure gradient from the atmosphere to the alveoli. As the pressure gradient increases, more air flows into the lungs.

Another possible answer:

Answer: E 
 The volume of air flowing into the alveoli during inhalation/inspiration is also influenced by the intrapleural pressure. If the intrapleural pressure is lower than the atmospheric pressure, the lungs will expand and more air will flow in. This is partly determined by the volume of air in the intrapleural space, which can be affected by factors such as changes in lung compliance, chest wall compliance, and intrathoracic pressure. If the intrapleural pressure is too high, it can compress the alveoli and make it harder to breathe.

Question 20

Which of the following statements regarding pulmonary surfactant is TRUE?

Accepted Answer

Pulmonary surfactant is secreted by type II alveolar cells and reduces surface tension in alveoli, hence increasing the compliance of the lungs. It does not affect airway resistance, is not secreted into the intrapleural space, and can interact with both lipid and protein molecules.

Quiz 13: Respiratory Physiology