5th Physiology Lecture Exam - Respiratory System (Batch 2024) Flashcards by

1.At the start of inspiration, alveoli are kept open by ___ pressure;
A.Negative alveolar
B.Negative trans airway
C.Positive intrapleural
D.Positive transpulmonary

D.Positive transpulmonary

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2.At high altitude, affinity of hemoglobin to oxygen decreases when there is INCREASED blood;
A.2,3 – diphosphoglycerate
B.CO2 pressure
C.O2 pressure
D.pH

A.2,3 – diphosphoglycerate

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3.A diver who breathes gas mixture of 50% O2, 50% Helium and works underwater where atmospheric 4 times the normal will experience one of these as he ascends to surface:
A.Apnea
B.Bends (or decompression sickness)
C.Nitrogen narcosis
D. O2 toxicity

B.Bends (or decompression sickness)

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4.The volume of air in the lungs at the end of normal expiration is:
A.Expiratory reserve volume
B.Functional residual capacity
C.Inspiratory capacity
D.Residual volume

B.Functional residual capacity

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5.The largest possible tidal volume is:
A.Functional residual capacity
B.Inspiratory capacity
C.Total lung capacity
D.Vital capacity

D.Vital capacity

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6.A reduction in one of these DECREASES O2 content of inspired air:
A.Altitude
B.Atmospheric pressure
C.Pleural pressure
D.Surfactant

B.Atmospheric pressure

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Central chemoreceptors are strongly stimulated by INCREASED arterial:
A. CO2 pressure
B. O2 pressure
C. pH
D. All of these

A. CO2 pressure

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Pulmonary edema will occur in one of these conditions:
A. Prolonged stay in outer space
B. Prolonged stay in deep sea
C. Rapid ascent to high altitude
D. Rapid descent to deep sea

C. Rapid ascent to high altitude

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Effect of centrifugal acceleratory force in the body includes:
A. Decreased bone mass
B. Decreased cardiac output
C. Increased diffusing capacity
D. Increased stroke volume

B. Decreased cardiac output

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Narcosis associated with deep sea diving is due to:
A. Damage of cellular metabolic systems
B. Depression of respiratory center
C. Formation of gas bubbles
D. Reduction in membrane excitability

D. Reduction in membrane excitability

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Mechanism of cerebral edema in acute mountain sickness is:
A. Reduction of blood pressure
B. Reduction of red blood cell mass
C. Vasodilation of cerebral vessels
D. Vasodilation of systemic vessels

C. Vasodilation of cerebral vessels

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Air embolism associated with deep sea diving is due to
A. Breath-holding during acsent
B. Breath-holding during descent
C. Rapid ascent to deep sea
D. Rapid ascent to surface

A. Breath-holding during acsent

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The reduction in lung volume during forceful expiration
is primarily due to:
A. Contraction of expiratory muscles
B. Elastance of chest wall
C. Elevation of alveolar pressure
D. Resistance of airways
E.

A. Contraction of expiratory muscles

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Physiologic effect of surface tension on lung is to:
A. Decrease forces that tend to collapse lungs
B. Decrease work to expand alveoli with each
breath
C. Increase (distending) pressure to keep lungs
Collapsed

D. Increase resistance of lungs to expand

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A reduction in of these DECREASES lung compliance
A. Alveolar ventilation
B. Pulmonary perfusion
C. Surfactant concentration
D. Transpulmonary pressure

C. Surfactant concentration

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The action of external intercostal muscles is to:
A. Elevate the rib cage
B. Lift the lungs upward
C. Pulls rib downward and inward
D. Push diaphragm upward

A. Elevate the rib cage

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The basic rhythm of respiration is due to:
A. Communication between neurons in pons
and medulla oblongata
B. Control neurons in medulla oblongata
C. Discharge of impulses from pontine neurons
D. Modulation of higher brain centers

B. Control neurons in medulla oblongata

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Which of these is a physiologic response to rapid
ascent to high altitude?
A. Decreased minute ventilation
B. Decreased pulmonary vascular resistance
C. Increased diffusing capacity
D. Increased tubular reabsorption of HCO3-

C. Increased diffusing capacity

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Effect of O2 toxicity associated with deep sea diving is:
A. Alveolar collapse due to loss of
surfactant
B. Apnea due to depression of respiratory
center
C. Convulsions due to decreased membrane excitability
D. Muscle paralysis due to formation of O2 bubbles

C. Convulsions due to decreased membrane excitability

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Mechanism of decompression sickness in deep sea
diving is:
A. Gas molecules dissolved in fat during
sudden ascent
B. Gas bubbles formed during sudden
ascent
C. Lung expansion during sudden descent
D. Respiratory inhibition during prolonged stay
beneath sea

B. Gas bubbles formed during sudden
ascent

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Effect of severe hypercapnia associated with deep sea
diving is:
A. Apnea
B. Atelectasis
C. Barotrauma
D. Chokes

A. Apnea

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The change in diffusing capacity during rapid ascent to
high altitude is due to INCREASED:
A. Arterial O2 pressure
B. Blood viscosity
C. Systemic blood pressure
D. Total lung capacity

D. Total lung capacity

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Effect of rapid ascent to high altitude on PaCO2 is
primarily due to:
A. Decreased airway resistance
B. Decreased cellular metabolism
C. Increased alveolar ventilation
D. Increased diffusing capacity

C. Increased alveolar ventilation

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Chronic mountain sickness is associated with
DECREASED:
A. Left ventricular diameter
B. Peripheral arterial pressure
C. Pulmonary arterial pressure
D. Red blood cell mass

B. Peripheral arterial pressure

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25. Use of helium in deep sea dives is preferred to nitrogen because HELIUM: A. Diffuse rapidly out of tissues B. Dissolves rapidly in blood C. Possesses greater density D. All of these

A. Diffuse rapidly out of tissues

26. During inspiration pleural pressure becomes: A. Equal to alveolar pressure due to increased lung volume B. Less negative due to chest wall expansion C. More negative due to increased elastic recoil of lungs D. Zero due to opposing elastic recoil o lungs and chest wall

C. More negative due to increased elastic recoil of lungs

27. Pleural pressure at the end of expiration is due to: A. Compliance of chest wall B. Compliance of lungs C. Outward recoil of chest wall D. Outward recoil of lungs

D. Outward recoil of lungs

28. Physiologic importance of surfactant is to DECREASE: A. Compliance of lungs B. Elastic recoil of lungs and chest wall C. Resistance of airways D. Surface tension of alveolar fluid

D. Surface tension of alveolar fluid

29. DECREASED inspiratory reserve volume DECREASES: A. Expiratory reserve volume B. Functional residual capacity C. Inspiratory capacity D. Tidal volume

C. Inspiratory capacity

30. Increased expiratory reserve volume will INCREASE: A. Functional residual capacity B. Inspiratory capacity C. Residual volume D. Tidal volume

A. Functional residual capacity

31. Work of breathing INCREASED when there is DECREASED: A. Airway resistance B. Atmospheric pressure C. Lung compliance D. Transpulmonary pressure

C. Lung compliance

32. The primary determinant of airway resistance is: A. Length of airway B. Radius of airway C. Temperature of air D. Viscosity of air

B. Radius of airway

33. Characteristic feature of alveolar epithelium that enhanced diffusion of gases is: A. Large diffusion distance B. Large surface area C. Thick respiratory membrane D. Thick surfactant layer

B. Large surface area

34. Role of respiratory neurons in medulla during quiet breathing is to: A. Activate expiratory neurons of ventral respiratory group (VRG) B. Activated inspiratory neurons of dorsal respiratory group (DRG) C. Inhibit expiratory neurons of VRG D. Inhibit inspiratory neurons of DRG

B. Activated inspiratory neurons of dorsal respiratory group (DRG)

35. Physiologic role of pneumotaxic center in upper pons is to: A. Decrease duration of expiration by stimulating DRG B. Increase respiratory rate by limiting duration of inspiration C. Modulate activity of inspiratory neurons by gas blood values D. Terminate inspiration by inhibiting DRG

B. Increase respiratory rate by limiting duration of inspiration

36. Respiratory rate increases when there is INCREASED: A. Duration of expiration B. Duration of inspiration C. Expiratory time D. Ramp signal

D. Ramp signal

37. Effect of hypoxemia on respiratory center is: A. Inhibition due to inhibition of central chemoreceptors B. Inhibition due to inhibition of peripheral chemoreceptors C. Stimulation due to activation of central chemoreceptors D. Stimulation due to activation of peripheral chemoreceptors

D. Stimulation due to activation of peripheral chemoreceptors

38. Which of these will have greater effect on central chemoreceptors? A. Acute hypercapnea B. Chronic hypercapnea C. Acute hypoxemia D. Chronic hypoxemia

B. Chronic hypercapnea

39. Peripheral chemoreceptors are strongly stimulated by LOW: A. Arterial pH B. PaCO2 C. PaO2 D. All of these

C. PaO2

40. Physiologic unit of respiratory system consists of: A. Lobar bronchi, non-respiratory bronchioles B. Respiratory bronchioles, alveolar ducts C. Segmental bronchi, terminal bronchioles D. Trachea, bronchi

B. Respiratory bronchioles, alveolar ducts

41. The lung volume that provides air in alveoli to oxygenate blood is: A. Expiratory reserve volume B. Inspiratory reserve volume C. Residual volume D. Tidal volume

C. Residual volume

42. The upper airways have one of these functions: A. Gas exchange B. Humidify inspired air C. Lighten skull D. Protect brain

B. Humidify inspired air

43. Restrictive lung diseases have one of these characteristics: A. High residual volume B. High vital capacity C. Low elastic recoil D. Low lung compliance

D. Low lung compliance

44. An example of restrictive lung diseases is: A. Bronchial asthma B. Chronic bronchitis C. Emphysema D. Pulmonary fibrosis

D. Pulmonary fibrosis

45. Increased residual volume/total lung capacity ratio in obstructive lung diseases is due to? A. High residual volume B. High total lung capacity C. Low residual volume D. Low total lung capacity

A. High residual volume

46. Residual volume/ total lung capacity ratio in restrictive lung disease is: A. High due to low residual volume B. High due to low total lung capacity C. Low due to high residual volume D. Low due to high total lung capacity

D. Low due to high total lung capacity

47. Stimulus to Hering-Breuer reflex is: A. Collapse of alveoli B. Distention of lungs C. Engorgement of pulmonary capillaries D. Irritation of airways

B. Distention of lungs

48. Type 1 alveolar epithelial cells is important for: A. Exchange of gases B. Maintenance of fluid balance C. Regeneration of alveolar structure D. Synthesis of surfactant

A. Exchange of gases

49. Non-respiratory function of lungs includes: A. Metabolism of epinephrine B. Removal inhaled particles C. Synthesis of angiotensin D. All of these

B. Removal inhaled particles

50. Effect of parasympathetic nervous system stimulation on respiratory system; A. Constrict airways and blood vessels B. Constrict airways, dilate blood vessels C. Dilate airways and blood vessels D. Dilate airways, constrict blood vessels

B. Constrict airways, dilate blood vessels

51. When tidal volume is 600 ml, respiratory rate is 15, anatomic dead space is 150:1ml, and the minute ventilation is _____ mL. A. 2250 B. 6750 C. 9000 D. 11250

C. 9000

52. Using the same values in question #51, the alveolar ventilation is _______ mL. A. 2250 B. 6750 C. 9000 D. 11250

B. 6750

53. Compared to restrictive lung disease, the lung compliance in obstructive lung disease is: A. High due to deposition of elastin fibers in lungs B. High due to loss of elastic recoil of lungs C. Low due to destruction of elastin fibers D. Low due to strong elastic recoil of lungs

B. High due to loss of elastic recoil of lungs

54. Function residual capacity INCREASES when there is INCREASED: A. Airway diameter B. Airway resistance C. Chest wall elastic recoil D. Chest wall muscle force

D. Chest wall muscle force

55. Engorgement of pulmonary capillaries will stimulate ____ receptors. A. Irritant B. J C. Mechanical D. Touch

B. J

56. Physiologic importance of bronchial circulation is to provide: A. Constant cardiac output B. Large reservoir of blood C. Oxygenated blood to lungs D. Regulator of vascular pressure

C. Oxygenated blood to lungs

57. During normal quiet breathing, lung expansion during inspiration is due to contraction of: A. Abdominal muscles B. Diaphragm C. External intercostals D. Internal intercostals

B. Diaphragm

58. Narrowing of airways INCREASES work of breathing due to INCREASED: A. Airways resistance B. Elastic recoil C. Lung compliance D. Tissue viscosity

A. Airways resistance

59. Flow rate in airways DECREASES when there is DECREASED: A. Length of airways B. Radius of airways C. Temperature of air D. Viscosity of air

B. Radius of airways

60. Function of pulmonary circulation includes: A. Pulmonary artery provides constant left ventricular output B. Pulmonary artery transports oxygenated blood C. Pulmonary vein provides large reservoir of blood D. Pulmonary vein transports unoxygenated blood

C. Pulmonary vein provides large reservoir of blood

61. Transpulmonary pressure is equal to: A. Alveolar pressure minus atmospheric pressure B. Alveolar pressure minus pleural pressure C. Atmospheric pressure minus pleural pressure D. Chest wall pressure minus alveolar pressure

B. Alveolar pressure minus pleural pressure

62. The most important controller of breathing is: A. Arterial pH B. Arterial CO2 pressure C. Arterial O2 pressure D. Serum H+

B. Arterial CO2 pressure

63. Physiologic significance of ramp signal is to: A. Expand lungs and chest wall smoothly B. Initiate basic rhythm of respiration rapidly C. Produce inspiratory gasps frequently D. Recoil lungs and chest wall elastically

B. Initiate basic rhythm of respiration rapidly

64. Respiratory changes during exercise includes an INCREASE in: A. Alveolar CO2 pressure B. Alveolar O2 pressure C. Alveolar ventilation D. Anatomic dead space

C. Alveolar ventilation

65. Astronauts upon return to earth after outer space exploration, experiencing fainting. This is due to: A. Decreased orthostatic tolerance B. Increased blood viscosity C. Loss of gravitational forces D. Unfamiliar pattern of motion signals to equilibrium center

A. Decreased orthostatic tolerance

A 55 yr old male has COPD. He complains that he easily gets tired when walking. Which of the following conditions would explain the increase in work of breathing in this patient? A. Physiological dead space is increased B. Anatomic dead space is increased C. Decreased total volume of gas in each breath that does not participate in gas exchange D. Physiologic dead space becomes as large as anatomic dead space

C. Decreased total volume of gas in each breath that does not participate in gas exchange ## Footnote In COPD, there is airway obstruction that leads to the retention of air in the lungs, resulting in increased residual volume and decreased expiratory flow rates. This, in turn, causes a decrease in the total volume of gas in each breath that participates in gas exchange. The increased work of breathing is due to the need to take more breaths to compensate for the decreased volume of gas participating in gas exchange. This is called increased "air hunger." Physiological dead space (A) is the volume of the respiratory system that does not participate in gas exchange, which includes the conducting airways and alveoli that are not perfused with blood. Anatomic dead space (B) is the volume of the conducting airways that does not participate in gas exchange. In COPD, the physiological dead space may be increased due to the destruction of alveoli, but this is not the primary cause of the increased work of breathing in this patient.

2. A 55 yr old male has COPD. He complains that he easily gets tired when walking. Which of the following would be an effective way to increase alveolar ventilation in this patient? A. Increase tidal volume B. Increase minute ventilation C. Increase residual volume D. Increase respiratory rate

B. Increase minute ventilation ## Footnote Alveolar ventilation refers to the amount of air that reaches the alveoli of the lungs, where gas exchange occurs. In COPD, the alveoli are often obstructed, making it difficult for air to flow in and out of the lungs and decreasing alveolar ventilation. This leads to a decrease in the amount of oxygen that reaches the bloodstream and an increase in the amount of carbon dioxide that builds up in the body.

3. Which of the following conditions would have the largest Alveolar-Arterial Difference for Oxygen? A. Normal lungs breathing 100% FiO2 B. Normal lungs breathing 50% FiO2 C. Breathing at 12,000 feet above sea level D. Patient with pulmonary fibrosis

D. Patient with pulmonary fibrosis ## Footnote The alveolar-arterial difference for oxygen (A-a gradient) is a measure of the difference between the amount of oxygen in the alveoli (the air sacs in the lungs) and the amount of oxygen in the arterial blood. A large A-a gradient indicates that there is a significant difference between the amount of oxygen in the alveoli and the amount of oxygen in the arterial blood, which can be indicative of a problem with oxygenation.

4. Which of the following statements regarding Carbon monoxide is CORRECT? A. Affinity of CO for Hgb is about 200 times greater than it is for O2 B. Affinity of Hgb for O2 is decreased in the presence of CO2 C. CO causes the dissociation curve to shift to the right D. A PCO of 1.0mm Hg in blood is compatible with life

A. Affinity of CO for Hgb is about 200 times greater than it is for O2

5. Which of the following statements is true of O2 transport? A. O2 exchange in the lungs is diffusion limited B. Affinity of hemoglobin for O2 decreases once O2 begins to bind to it C. Presence of fetal hemoglobin increases affinity for O2 D. Main transport mechanism of O2 is dissolved in blood

C. Presence of fetal hemoglobin increases affinity for O2

6. Which of the following is NOT a characteristic of carbon monoxide poisoning? A. Treatment consists of administering hyperbarbic oxygen B. Affinity of CO for hemoglobin is about 200 times greater than it is for O2 C. Small amounts of CO can greatly influence the binding of O2 to hemoglobin D. Binds to the globin group of haemoglobin

A. Treatment consists of administering hyperbarbic oxygen

Which of the following statements regarding the functional zones of the lung is CORRECT? A. Capillaries in zone 1 collapse because of the greater external arterial pressure and blood flow ceases B. Alveolar pressure is greater than arterial pressure, which is in turn is greater than venous pressure in zone 2 С. Blood flows in zone 3 in accordance with the pressure gradients D. Greater alveolar pressure in zone 3 partially collapses the capillaries and causes a "damming" effect

C. Blood flows in zone 3 in accordance with the pressure gradients

Which of the following statement correctly explain the Haldane effect? A. High affinity of oxygen for hemoglobin in the lungs facilitates removal of carbon dioxide B. Increased ability of hemoglobin to carry CO2 in the oxygenated state C. Oxygenated Hgb more readily forms carbamino compounds D. HCO3- diffuses out of the red blood cell in exchange for CI-

A. High affinity of oxygen for hemoglobin in the lungs facilitates removal of carbon dioxide

9. Which of the following effects of lung volume on pulmonary vascular resistance (PVR) is CORRECT? A. The air-filled alveoli compresses the alveolar capillaries and decrease PVR at end inspiration B. Total pulmonary vascular resistance in the lung is lowest at functional residual capacity C. Inflation from residual volume to total lung capacity decreases resistance to blood flow through alveolar vessels D. The deflated alveoli during exhalation apply the most resistance to the alveolar capillaries and increases PVR

B. Total pulmonary vascular resistance in the lung is lowest at functional residual capacity

10. If a 40-year-old woman residing in Manila and decides to go to Baguio, which of the following conditions is expected as a result of residing at high altitudes? A. Respiratory acidosis due to hyperventilation B. Hypoventilation due to decreased PO2 C. Pulmonary vasodilation due to alveolar hypoxia D. Shift to the left of O2 dissociation curve due to increase 2,3-Diphosphoglycerate

D. Shift to the left of O2 dissociation curve due to increase 2,3-Diphosphoglycerate

11. A patient with pulmonary fibrosis complains of tachypnea. Given the following arterial blood gases: pH = 7.48, Pa02 = 55 mm Hg, PaCO2 = 32 mm Hg. Which of the following mechanisms would best explain the results? A. Increased pH causes hyperventilation resulting in decreased PaO2 leading to a decreased PaCO2 B. Decreased PaCO2 causes hyperventilation resulting in decreased PaO2 leading to a decreased PaO2 C. Decreased PaO2 causes hyperventilation resulting in increased pH leading to a decreased PaCO2 D. Decreased PaO2 causes hyperventilation resulting in decreased PaCO2 leading to an increased pH

D. Decreased PaO2 causes hyperventilation resulting in decreased PaCO2 leading to an increased pH. This is known as respiratory alkalosis, which occurs due to hyperventilation causing a decrease in PaCO2. In this case, the underlying cause of hyperventilation is likely the decreased PaO2 due to pulmonary fibrosis.

12. Which of the following properties is true of the CO2 dissociation curve? A. Degree of Hemoglobin saturation with O2 does not affect the CO2 dissociation curve B. Inversely related to PCO2 C. CO2 dissociation curve is non-linear D. PCO2 is solely dependent on alveolar ventilation and CO2 production

B. Inversely related to PCO2

13. Which of the following causes of hypoxia is characterized by a decreased arterial PO2 and an increased A-A gradient? A. Right-to-left cardiac shunt B. Anemia C. Breathing at high altitude D. Hypoventilation

A. Right-to-left cardiac shunt

14. What is the effect of Pulmonary fibrosis on the diffusion capacity of the lung for carbon monoxide (DLCO)? A. Promote absorption of carbon dioxide B. Decrease C. Promote absorption of carbon monoxide D. Increase

B. Decrease ## Footnote The correct answer is B. Pulmonary fibrosis leads to a thickening of the alveolar-capillary membrane, which increases the diffusion distance for gases, including carbon monoxide. This results in a decreased diffusion capacity of the lung for carbon monoxide (DLCO).

15. Which of the following conditions would increase the oxygen tension in inspired ambient air ? A. Increasing volume of inspired air B. Increasing the barometric pressure C. Increasing the fraction of inspired O2 in air D. Increasing minute ventilation

Increasing the fraction of inspired O2 in air

. An asthmatic patient (obstructive disease) is experiencing an acute exacerbation. The following results were obtained from his arterial blood gas: Pa02 is 65 mmHg and PaCO2 is 30 mmHg. Which of the following statements would be correct? A. Residual volume is decreased B. Pa02 is higher than normal because of inadequate gas exchange C. PaCO2 is lower than normal because of hyperventilation D. Ventilation/perfusion is increase

C. PaCO2 is lower than normal because of hyperventilation ## Footnote C. PaCO2 is lower than normal because of hyperventilation. In acute exacerbation of asthma, the airways become narrowed due to inflammation and constriction of the smooth muscle in the bronchial walls, which leads to decreased airflow and increased air trapping in the lungs. This causes hyperventilation and a decrease in PaCO2 due to the increased removal of carbon dioxide. The decrease in PaO2 is due to inadequate gas exchange caused by the obstruction of airways and decreased ventilation-perfusion matching. Residual volume may be increased due to air trapping in the lungs.

17. Which of the following conditions would shift the oxygen dissociation curve to the right? A. Decreased 2,3-diphosphoclycerate (DPG) concentration B. Fetal hemoglobin (HbF) C. Increased pH D. Strenuous exercise

A. Decreased 2,3-diphosphoclycerate (DPG) concentration

18. Which of the following events occur during the transport of CO2 from the tissues to the lungs? A. Buffering of H+ by oxyhemoglobin B. Alkalinzation fo red blood cells C. Conversion of CO2 and H2O to H+ and HCO3- in the red blood cells D. Movement of HCO3- into the red blood cells from plasma exchange for Cl-

C. Conversion of CO2 and H2O to H+ and HCO3- in the red blood cells ## Footnote C. Conversion of CO2 and H2O to H+ and HCO3- in the red blood cells occurs during the transport of CO2 from the tissues to the lungs. This process is catalyzed by carbonic anhydrase, an enzyme present in red blood cells, and leads to the formation of bicarbonate (HCO3-) and hydrogen ions (H+). The HCO3- is transported out of the red blood cells into the plasma in exchange for chloride ions (CI-), and the H+ binds to hemoglobin or other buffers to prevent a decrease in pH. In the lungs, the process is reversed, and HCO3- is converted back to CO2 and H2O, which are then exhaled.

19. Which of the following features does NOT facilitate gas diffusion throughout the respiratory system? A. Large surface for gas exchange B. Long distance to travel C. Partial pressure gradient differences D. Diffusion properties of the gas

B. Long distance to travel

20. Which of the following statements is correct when describing the regulation of acid-base balance? A. Oxyhemoglobin is a better buffer for H+ than is deoxyhemoglobin B. HCO3- diffuses into the red blood cell in exchange for Cl- C. H2CO3 is converted into CO2 and H2O by the action of carbonic anhydrase D. pH of venous blood is only slightly more acidic than the pH of arterial blood

C. H2CO3 is converted into CO2 and H2O by the action of carbonic anhydrase

21. What is the partial pressure of O2 in the artery of an area of the lung that is not ventilated? A. Equal to atmospheric PO2 B. Equal to mixed venous PO2 C. Higher than inspired PO2 D. Lower than mixed venous PO2

B. Equal to mixed venous PO2

22. Which of the following V/Q defects will supplemental O2 provides the most benefit; A. V/Q = 0 B. Low V/Q C. V/Q = ∞ D. High V/Q

B. Low V/Q

1. Which of the following conditions would you expect the highest diffusion rate of oxygen in the lungs? A. PAO2: 150 mmHg: 40 mmHg, surface area: 7 B. PAO2: 300 mmHg, PVO2: 40 m,Hg, surface area: 2 C. PAO2: 150 mmHg: 80 mmHg, surface area: 1 D. PAO2: 100 mmHg: 40 mmHg, surface area: 1

A. PAO2: 150 mmHg: 40 mmHg, surface area: 7 ## Footnote Option A would have the highest diffusion rate of oxygen in the lungs because it has a high partial pressure gradient (PAO2-PVO2) of 110 mmHg and a large surface area of 70 square meters (7 times the other options), which allows for more gas exchange. The other options have lower partial pressure gradients or smaller surface areas, which would result in lower diffusion rates.

24. Which of the following statements is CORRECT with regards to the regulation of blood flow in the pulmonary circulation? A. High levels of inspired O2 can dilate pulmonary vessels and decrease PVR. B. High inspired O2 levels as a result of high altitude have a greater effect on PVR. C. Hypoxic vasoconstriction occurs in arterioles in response to increased PAO2. D. Decreased expression of endothelin-1 has been found in individuals with pulmonary artery hypertension.

A. High levels of inspired O2 can dilate pulmonary vessels and decrease PVR

25. Which of the following vascular beds will vasoconstrict during hypoxia? A. Cerebral B. Coronary C. Skin D. Pulmonary

D. Pulmonary

26. In patients suffering from pulmonary embolism with complete obstruction, which of the following conditions is expected to occur? A. Increased system arterial PO2 B. Ventilation/perfusion (V/Q) ratio in the affected lung will be zero C. Partial pressure of O2 in the alveolus in the affected lung will be approximately equal to the PO2 in inspired air D. Partial pressure of O2 in the alveolus in the unaffected lung will be approximately equal to the PO2 in venous blood

B. Ventilation/perfusion (V/Q) ratio in the affected lung will be zero

27. Which of the following is correct of perfusion limited gases? A. Limited only by the amount of blood perfusion the alveolus B. Chemically combine with proteins in blood C. Involves gases that have a slow rate of airto- blood equilibration D. Equilibration occurs in prolonged capillary transit time

A. Limited only by the amount of blood perfusion the alveolus

28. Which of the following conditions would increase alveolar ventilation? A. Increased respiratory quotient B. Decreased partial pressure of CO2 in the artery C. Respiratory alkalosis D. Increased partial pressure of CO2 in the alveolus

D. Increased partial pressure of CO2 in the alveolus

29. Which of the following statements is true of the alveolar carbon dioxide equation? A. Direct relationship between the partial pressure of CO2 in the alveolus and alveolar ventilation per minute B. Doubling of the metabolic production of CO2 decreases the partial pressure of CO2 in the alveolus by half C. If ventilation is doubled, partial pressure of CO2 in the alveolus decreases by 50% D. If ventilation is doubled, the partial pressure of CO2 in the alveolus doubles

C. If ventilation is doubled, partial pressure of CO2 in the alveolus decreases by 50%

30. Which of the following factors will NOT stimulate erythropoietin secretion (hypoxia)? A. Low oxygen delivery B. Low PaO2 C. Low PaCO2 D. Low hemoglobin concentration

C. Low PaCO2

31. Which of the following characterizes a gas as being diffusion limited? A. Rapid equilibration of partial pressure between alveolar gas and blood during the red blood cell transit time B. Large amounts of gas to be taken up in blood with large increase in its partial pressure C. Low solubility in blood because of low affinity for hemoglobin D. Occurs if red blood cells spent less than 0.25 seconds in the capillary bed

B. Large amounts of gas to be taken up in blood with large increase in its partial pressure ## Footnote Diffusion limitation occurs when the rate of gas diffusion is limited by the ability of the gas to dissolve into the blood. This happens when there is a large amount of gas to be taken up in blood with a large increase in its partial pressure, making it difficult for the gas to dissolve quickly. In contrast, when gas exchange is perfusion-limited, the rate of gas diffusion is limited by the blood flow through the pulmonary capillaries, and the partial pressure of the gas in the blood equilibrates rapidly with that in the alveolar gas during the red blood cell transit time.

32. Which of the following principles of the O2 dissociation curve is correct? A. S shape of the curve demonstrates the dependence of PO2 on hemoglobin saturation B. In the steep portion, a large amount of O2 is released from Hgb with only a small change in PO2 C. At P50 the hemoglobin saturation is at 27% D. In the plateau area, changes in PO2 has a major effect on Hgb saturation from 100% to 90%

A. S shape of the curve demonstrates the dependence of PO2 on hemoglobin saturation

33. Which of the following causes of hypoxia would have a normal Alveolar-arterial Difference for Oxygen? A. Anatomic shunt B. Diffusion abnormality C. Hypoventilation D. Low ventilation/perfusion ratio

C. Hypoventilation

34. Which of the following is seen when there is a shift to the right of the oxygen dissociation curve? A. Decreased O2-carrying capacity of hemoglobin B. Increased affinity of hemoglobin for O2 C. Increased O2-carrying capacity of hemoglobin D. Increased unloading of O2 in the tissues

A. Decreased O2-carrying capacity of hemoglobin ## Footnote A. Decreased O2-carrying capacity of hemoglobin. A shift to the right of the oxygen dissociation curve indicates a decrease in the affinity of hemoglobin for oxygen, which means that at any given partial pressure of oxygen, hemoglobin will release more oxygen to the tissues. This results in a decreased O2-carrying capacity of hemoglobin, which can be advantageous in situations where the tissues require more oxygen, such as during exercise or in high-altitude environments.

35. Which of the following statements is correct with regards to Bohr Effect? A. Increase in CO2 production by tissue decreases the pH and shift the dissociation curve to the left B. Increase in CO2 production by tissu increases the pH and shift the dissociation curve to the right C. When CO2 is exhaled pH rises and causes the oxyhemoglobin dissociation curve to shift to the left D. When CO2 is inhaled pH rises and causes the oxyhemoglobin dissociation curve to shift to the left

A. Increase in CO2 production by tissue decreases the pH and shift the dissociation curve to the left

5th Physiology Lecture Exam - Respiratory System (Batch 2024) Flashcards

(100 cards)