Deck 13: Respiratory Physiology

Question 1

Which is TRUE regarding how gasses dissolve in liquids?

A) The concentration of a particular gas in a liquid equilibrates to match the concentration of that gas in the air to which the liquid is exposed.
B) Different gasses have the same solubility in liquids.
C) The partial pressure of a gas in a liquid is equal to the amount freely diffusing in the liquid plus the amount bound to large molecules within the liquid.
D) The partial pressure of a particular gas in a liquid equilibrates to match the partial pressure of that gas in the air to which the liquid is exposed.
E) As the partial pressure of a particular gas in an air sample increases, the concentration of that gas in a liquid exposed to that air sample decreases.

Answer 1

D

Question 2

A respiratory physiologist has measured ventilation parameters for each of three subjects: Tidal volume (TV); Respiratory rate (RR), and Anatomic dead space volume (ADSV). Which of the following statements accurately compares the alveolar ventilation in the three men?

A) Tom's is the largest; Dick's and Harry's are the same.
B) Tom's is the smallest; Dick's and Harry's are the same.
C) Tom's is greater than Dick's, which is greater than Harry's.
D) Dick's is greater than Harry's, which is greater than Tom's.
E) Harry's is greater than Dick's, which is greater than Tom's.

Answer 2

E

Question 3

What is one function of the type II alveolar cells?

A) production of surfactant
B) secretion of mucus
C) phagocytizing bacteria and other foreign particles
D) make up the majority of the epithelial wall of the alveoli
E) lining the pleural space

Answer 3

A

Question 4

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

A) bronchiole
B) trachea
C) bronchus
D) respiratory bronchiole
E) terminal bronchiole

Question 5

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 6000 mL; and his anatomic dead space is 150 mL. Joe's resting alveolar ventilation is:

A) 72.0 L/min
B) 6.0 L/min
C) 4.2 L/min
D) 1.8 L/min
E) 0.5 L/min

Question 6

Which of the following drugs, administered as an aerosol spray, would be most likely to help an infant with respiratory distress syndrome of the newborn?

A) pulmonary surfactant
B) a beta-adrenergic agonist
C) a muscarinic agonist
D) histamine
E) a beta-adrenergic antagonist

Question 7

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?

A) 6.0
B) 5.2
C) 4.2
D) 3.0
E) 0.583

Question 8

Which of these causes inhalation/inspiration?

A) increase in the curvature (upward movement) of the diaphragm
B) movement of the ribs closer together due to contraction of the internal intercostal muscles
C) flattening (downward movement) of the diaphragm
D) contraction of the abdominal muscles
E) alveolar pressure increasing above atmospheric pressure

Question 9

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

A) airway resistance
B) the pressure gradient from the atmosphere to the alveoli
C) the pressure in the intrapleural space
D) the curvature of the diaphragm
E) the volume of air in the intrapleural space

Question 10

Under what conditions is lung compliance increased?

A) respiratory distress syndrome of the newborn
B) prolonged shallow breathing
C) cystic fibrosis
D) emphysema
E) asthma

Question 11

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

A) the presence of surfactant
B) the negative pressure in the alveolar space
C) the force exerted by the external intercostal muscles
D) subatmospheric intrapleural pressure
E) alveolar pressure is higher than atmospheric pressure

Question 12

Which is TRUE about the pleural sac?

A) It is continuous with the atmosphere and protects the lungs from infection.
B) It is a closed sac surrounding each lung that contains only a tiny volume of lubricating fluid.
C) It is a closed sac surrounding each lung and contains a large volume of surfactant.
D) It is a closed, air-filled space surrounding both lungs that has a negative pressure compared to atmospheric pressure.
E) It is bounded by pleural membranes that are very thin, which allows for abundant gas exchange.

Question 13

Which of the following statements regarding pulmonary surfactant is TRUE?

A) It is secreted by type I alveolar cells.
B) It increases the compliance of the lungs.
C) It increases airway resistance.
D) It is secreted into the intrapleural space.
E) It can only interact with other lipid molecules.

Question 14

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

A) pulmonary surfactant
B) a $\beta$ ₂-adrenergic agonist
C) a muscarinic agonist
D) histamine
E) a $\beta$ ₂-adrenergic antagonist

Question 15

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

A) inhalation/inspiration
B) exhalation/expiration
C) a collapsed lung
D) pneumothorax
E) emphysema

Question 16

Which is normally TRUE about the intrapleural pressure?

A) It is lower than alveolar pressure.
B) It is between +5 and +10 mm Hg above atmospheric pressure at functional residual capacity.
C) It alternates between being less than, and greater than, atmospheric pressure.
D) During a passive exhale, it increases to a value above atmospheric pressure.
E) It is always the same as atmospheric pressure during a passive exhale.

Question 17

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

A) Both systemic and pulmonary arterioles respond to a decrease in P_O2 by constricting.
B) Both systemic and pulmonary arterioles respond to a decrease in P_O2 by dilating.
C) Systemic arterioles respond to a decrease in P_O2 by dilating, but pulmonary arterioles constrict in response to decreased P_O2.
D) Systemic arterioles respond to a decrease in P_O2 by constricting, but pulmonary arterioles dilate in response to decreased P_O2.
E) Changes in P_O2 do not affect arteriolar smooth muscle in the pulmonary system.

Question 18

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

A) net uptake of carbon dioxide from the air and removal of oxygen from the blood
B) regulation of blood H⁺ concentration
C) trapping of blood clots
D) phonation
E) defense against microbes

Question 19

During an unforced exhalation/expiration, which would NOT be true?

A) Alveolar pressure is greater than atmospheric pressure.
B) Intrapleural pressure is greater than alveolar pressure.
C) Intrapleural pressure becomes leess negative.
D) The diaphragm relaxes.
E) Lung volume decreases.

Question 20

Which of the following is a cause of asthma?

A) loss of alveoli
B) inflammation of the bronchioles
C) elevation of intrapleural pressure to equal atmospheric pressure
D) environmental chemicals that stimulate $\beta$ ₂-adrenergic receptors
E) lack of pulmonary surfactant

Question 21

Curve B below represents the oxygen-hemoglobin dissociation curve for normal body temperature, arterial hydrogen ion concentration, and DPG concentration.

A) Curve A may represent the dissociation at higher than normal arterial H+ concentration.
B) Curve C may represent the dissociation at lower than normal body temperature.
C) Curve A may represent the dissociation at very low 2,3 diphosphoglycerate levels.
D) Curve C may represent the dissociation at lower than normal arterial H+ concentration.
E) Curve A may represent the dissociation at higher than normal body temperature.

Question 22

Which of the following would cause a decrease in the binding affinity of hemoglobin for oxygen?

A) increased pH of the blood
B) increased temperature of the blood
C) decreased DPG levels in erythrocytes
D) the presence of carbon monoxide
E) decreased concentration of H⁺ in the blood

Question 23

If all other factors remain the same, which of these results in an increase in the amount of oxygen bound to hemoglobin?

A) increased plasma [H+]
B) increased plasma temperature
C) increased plasma [2,3 diphosphoglycerate]
D) increased plasma P_O2
E) increased plasma [carbon monoxide]

Question 24

Regarding the partial pressures of O₂ and CO₂, which of the following statements is NOT true in a normal person at rest?

A) Atmospheric P_O2 is greater than alveolar P_O2.
B) The P_CO2 in air is less than alveolar P_CO2.
C) The P_O2 in systemic arteries is typically greater than the alveolar P_O2.
D) P_CO2 in the systemic veins is greater than systemic arterial P_CO2.
E) P_CO2 in the pulmonary arteries is greater than pulmonary venous P_CO2.

Question 25

Which is a result of hyperventilation?

A) respiratory alkalosis
B) respiratory acidosis
C) increased blood P_CO2
D) metabolic acidosis
E) metabolic alkalosis

Question 26

Which of these correctly describes the chloride shift?

A) In the lungs, chloride enters red blood cells in exchange for bicarbonate ions.
B) In the tissues, chloride exits red blood cells in exchange for carbonic acid.
C) In the tissues, chloride enters red blood cells in exchange for bicarbonate ions.
D) In the lungs, chloride enters red blood cells in exchange for CO₂.
E) In the tissues, chloride enters red blood cells in exchange for CO₂.

Question 27

After CO₂ is produced by tissues, in what form is most of that carbon transported to the lungs for removal from the body?

A) as dissolved CO₂
B) bound to hemoglobin
C) as H₂CO₃
D) as dissolved HCO₃^-
E) as carbonic anhydrase

Question 28

Action potentials in neurons in the inspiratory center of the medulla oblongata result in action potentials in the ________ nerves to the diaphragm, which in turn cause ________ of the muscle, resulting in a/an ________ in the volume of the thoracic cage.

A) motor; contraction; decrease
B) parasympathetic; contraction; decrease
C) sympathetic; contraction; increase
D) motor; contraction; increase
E) sympathetic; relaxation; increase

Question 29

Regarding the relationships between the rates of oxygen consumption/carbon dioxide production and alveolar ventilation, which of these statements is TRUE?

A) Increased ventilation without a similar increase in metabolism is called hypoventilation.
B) In hypoventilation, alveolar P_CO2 decreases below resting levels.
C) In hyperventilation, alveolar P_CO2 can decrease to zero.
D) A decrease in metabolism without a similar decrease in alveolar ventilation would result in hyperventilation.
E) An increase in ventilation with a matching increase in metabolism is called hyperventilation.

Question 30

Which occurs as a result of hypoventilation?

A) the pH of the blood increases
B) levels of blood O₂ increase
C) levels of blood H⁺ ions increase
D) alveolar CO₂ decreases to near atmospheric levels
E) alveolar oxygen increases toward atmospheric levels

Question 31

In which form is most of the oxygen carried in arterial blood?

A) bound to hemoglobin
B) dissolved in the plasma
C) dissolved in the cytosol of erythrocytes
D) converted to HCO₃^-
E) bound to myoglobin

Question 32

Carbonic anhydrase catalyzes a reaction that combines which of the following?

A) H₂O and O₂
B) H₂O and CO₂
C) H₂O and CO
D) H⁺ and HCO₃^-
E) CO₂ and O₂

Question 33

What brain center has neurons that fire mainly during inspiration and have input to the spinal motor neurons that activate the diaphragm and inspiratory intercostal muscles?

A) the ventral respiratory group of the medulla oblongata
B) the pre-Bötzinger complex
C) the dorsal respiratory group of the medulla oblongata
D) the pneumotaxic center of the pons
E) the apneustic center of the pons

Question 34

What is the primary regulator of the magnitude of alveolar ventilation under normal circumstances?

A) the H⁺ concentration in the brain extracellular fluid, which is monitored by central chemoreceptors
B) The PO₂ of the arterial blood, which is monitored by central chemoreceptors
C) The PO₂ of the arterial blood, which is monitored by peripheral chemoreceptors
D) the H⁺ concentration in the arterial blood, which is monitored by central chemoreceptors
E) stretch receptors in the lung

Question 35

Which of these results from hyperventilation?

A) increased alveolar P_CO2 and decreased alveolar P_O2
B) an increase in both alveolar P_CO2 and P_O2
C) decreased alveolar P_CO2 and increased alveolar P_O2
D) a decrease in both alveolar P_CO2 and P_O2
E) the same alveolar P_CO2 as under normal conditions

Question 36

Which of the following is most responsible for detecting an increase in systemic arterial H⁺ concentration?

A) the medulla of the brainstem
B) the peripheral chemoreceptors
C) the central chemoreceptors
D) the diaphragm
E) the dorsal respiratory group

Question 37

Which of the following are chemoreceptors?

A) hair cells in the cochlea
B) receptors in the aortic and carotid bodies
C) baroreceptors in the aortic and carotid arch
D) receptors that mediate the Hering-Breuer reflex

Question 38

Which of these is demonstrated by the oxygen-hemoglobin dissociation curve?

A) The greater the P_O2 of the blood, the greater the dissociation of O₂ from hemoglobin.
B) At normal resting systemic arterial P_O2 , hemoglobin is almost 100% saturated with oxygen.
C) At normal resting systemic venous P_O2 , only about 75% of the hemoglobin is in the form of deoxyhemoglobin.
D) More additional oxygen binds to hemoglobin when going from a P_O2 of 60 to 100 mmHg, than is added when going from a P_O2 of 40 to 60 mmHg.
E) As P_O2 increases, the saturation of hemoglobin with oxygen increases linearly.

Question 39

Which of the following statements regarding the transport of CO₂ in blood is FALSE?

A) Some of the CO₂ in blood is dissolved in plasma.
B) Some of the CO₂ in blood is dissolved in the cytosol of erythrocytes.
C) Some of the CO₂ in blood is bound to hemoglobin.
D) Most of the CO₂ in blood is converted to another molecule.
E) Some of the CO₂ in blood is converted to chloride.

Question 40

Which of the following is NOT true regarding ventilation-perfusion inequality?

A) No inequality exists in normal lungs.
B) It may result from increased alveolar dead space.
C) It is increased from normal in patients with emphysema.
D) It is caused by too little or too much blood flow relative to ventilation.
E) It is caused by too little or too much ventilation relative to blood flow.

Question 41

Normal, resting exhalation/expiration of air from the lungs requires contraction of the exhalatory/expiratory intercostal muscles.

Question 42

Which of the following conditions would result in a systemic arterial P_O2 lower than is typical of a healthy person at sea level?

A) traveling to high altitude
B) breathing 100% oxygen
C) having iron-deficiency anemia
D) breathing regular air in a hyperbaric chamber (higher that normal atmospheric pressure)
E) maintaining alveolar ventilation constant while decreasing metabolic rate

Question 43

Which correctly describes the cause of the increase in alveolar ventilation that occurs when a person ascends to high altitude?

A) The decrease in P_CO2 of inspired air decreases alveolar P_CO2, stimulating the peripheral chemoreceptors.
B) The decrease in P_CO2 of inspired air decreases alveolar P_CO2, stimulating the central chemoreceptors.
C) The decrease in P_O2 of inspired air decreases alveolar and arterial P_O2, stimulating the peripheral chemoreceptors.
D) The decrease in total atmospheric pressure causes a greater negative pressure in the intrapleural space, resulting in deeper and more frequent breathing.
E) The decrease in the total barometric pressure at high altitude causes hypocapnea, which stimulates peripheral chemoreceptors.

Question 44

Which of these does NOT increase during heavy exercise?

A) minute ventilation
B) arterial P_CO2
C) oxygen delivery to muscles
D) oxygen extraction from the blood by muscles
E) body heat production

Question 45

If the parietal pleura is cut during surgery, the lung on the side of the cut will expand and the chest wall will be compressed.

Question 46

The diameter of the airways in normal lungs is generally great enough that little resistance is offered to airflow.

Question 47

During inhalation/inspiration, the total alveolar volume decreases.

Question 48

In a normal person at rest, the part of the respiratory cycle in which no air is flowing through the airways and the respiratory muscles are relaxed is at the end of inhalation/inspiration, prior to exhalation/expiration.

Question 49

If the nerves from the carotid and aortic bodies are cut, which of these would occur?

A) A decrease in arterial P_O2 will no longer increase ventilation.
B) An increase in arterial P_CO2 will no longer increase ventilation.
C) An increase in arterial lactic acid will inhibit ventilation.
D) An increase in arterial P_CO2 will inhibit ventilation.
E) A decrease in arterial P_O2 will inhibit ventilation.

Question 50

The process of ventilation includes both the transport of gases by bulk flow and the diffusion of gases into and out of the blood.

Question 51

Emphysema is a disease characterized by low lung compliance, obstructed airways, and ventilation-perfusion inequality.

Question 52

According to Boyle's law, the pressure exerted by a constant number of gas molecules in a container is inversely proportional to the volume of the container. Therefore, increasing the volume of the container will cause a decrease in its pressure.

Question 53

Following strenuous exercise, blood levels of lactic acid are ________ compared to pre-exercise levels. This change in acid concentration causes a reflex ________ in ventilation by activating ________.

A) decreased; decrease; peripheral chemoreceptors
B) decreased; decrease; central chemoreceptors
C) increased; increase; baroreceptors in the aortic arch
D) increased; increase; central chemoreceptors
E) increased; increase; peripheral chemoreceptors

Question 54

During inhalation/inspiration, the diaphragm contracts and the alveolar pressure is less than atmospheric pressure; during exhalation/expiration, the diaphragm relaxes and the alveolar pressure is greater than atmospheric pressure.

Question 55

Which is characteristic of a person chronically suffering from hypoxic hypoxia?

A) higher-than-normal alveolar P_O2
B) higher-than-normal hematocrit
C) higher-than-normal arterial P_O2
D) lower-than-normal lactic acid production
E) lower-than-normal blood flow through tissues

Question 56

Which of the following statements regarding hypoxia is correct?

A) Exposure to high altitude is a form of hypoxic hypoxia.
B) "Anemic hypoxia" refers to the condition of lower than normal arterial P_O2.
C) Carbon monoxide poisoning is an example of hypoxic hypoxia.
D) Carbon monoxide poisoning is an example of ischemic hypoxia.
E) Cyanide poisoning is an example of hypoxic hypoxia.

Question 57

Which of these would tend to increase ventilation?

A) lower than normal arterial P_CO2
B) higher than normal arterial pH
C) breathing carbon monoxide
D) breathing air with increased P_CO2
E) iron-deficiency anemia

Question 58

Which of the following statements regarding control of respiration is correct?

A) A slight decrease in arterial P_O2 is a stronger stimulus for increased ventilation than is a comparable decrease in arterial P_CO2.
B) The most important signal for regulating ventilation is the H⁺ concentration of arterial blood.
C) Increased concentrations of lactic acid stimulate ventilation primarily by acting on peripheral chemoreceptors.
D) An increase in the HCO₃^- concentration in blood stimulates ventilation.
E) At high altitude, a decrease in P_CO2 of the blood stimulates an increase in ventilation.

Question 59

The diaphragm is a large sheet of smooth muscle that separates the thoracic cavity from the abdomen.

Question 60

Infants born prematurely frequently develop respiratory distress syndrome of the newborn because they have too few alveoli to exchange O₂ and CO₂ efficiently.

Question 61

The affinity of hemoglobin for O₂ is decreased in rapidly metabolizing tissues.

Question 62

A clinical sign of obstructive lung disease would be a reduced FEV1/FVC ratio, where "FVC" is "forced" VC.

Question 63

When a person hyperventilates, there are lower than normal levels of P_CO2 and hydrogen ion in arterial blood, a condition called respiratory alkalosis.

Question 64

At sea level, atmospheric P_O2 is about 760 mmHg.

Question 65

The medullary inspiratory neurons receive inhibitory neural input from the pons and also from pulmonary stretch receptors.

Question 66

Most of the O₂ carried in the blood is dissolved in plasma.

Question 67

Decreased alveolar P_O2 causes reflex vasodilation of the pulmonary arterioles.

Question 68

The majority of hydrogen ions generated in the formation of carbonic acid in the tissues are carried as freely dissolved H⁺ in the venous blood.

Question 69

Of the CO₂ returning from the tissues in venous blood, more is dissolved in plasma as CO₂ than is bound to hemoglobin.

Question 70

The rhythmic contractions and relaxations of the inspiratory muscles are dependent upon spontaneous depolarizations of the diaphragm.

Question 71

Deoxyhemoglobin binds bicarbonate ion better than oxyhemoglobin does.

Question 72

The neurons responsible for the cyclic nature of respiratory muscle function are located in the brainstem.

Question 73

The total dead space in the lungs includes anatomic dead space and any portion of the alveoli that has little or no blood supply.

Question 74

When blood flows into the systemic capillaries, the P_O2 of the erythrocytes is greater than the P_O2 of the interstitial fluid, causing a shift from oxyhemoglobin to deoxyhemoglobin.

Question 75

A decrease in arterial P_O2 stimulates increased ventilation by causing increased firing of action potentials in the afferent neurons from the carotid and aortic body chemoreceptors.

Question 76

Mixed venous blood in a resting individual still contains more than double the amount of oxygen extracted by the tissues as the blood passed through them.

Question 77

Doubling the frequency of breathing will cause a greater increase in alveolar ventilation than will doubling the depth of inspiration.

Question 78

Normally, all the H⁺ ions generated from CO₂ in tissue capillaries recombine with bicarbonate in pulmonary capillaries and are removed from the body as CO₂.

Question 79

In the systemic circulation, the P_O2 of arterial blood exceeds the P_O2 of venous blood, while the reverse is true for the pulmonary circulation.

Question 80

If lung disease results in an arterial P_O2 of 80 mmHg, the total amount of oxygen carried by the blood is 20% below normal.