STUDY QUESTIONS
Blood Gases
Answers are provided below each question

1) Plasma is:
    a) blood that has no red blood cells
    b) the liquid portion of blood including clotting factors
    c) the liquid portion of blood after it has clotted
    d) the proteins of blood
   

2) Most oxygen carried in the blood is:
  1. In solution with the plasma
  2. Combined with plasma proteins
  3. Chemically combined with a heme group
  4. Carried as HCO3-
  5. Bound to the amino acid valine on the beta chain of hemoglobin
3) Which statement about CO2 is incorrect?
  1. Its concentration in the blood is decreased by hyperventilation
  2. Its accumulation in the blood is associated with a drop in pH
  3. More CO2 dissolves in the blood plasma than is carried on RBCs
  4. [CO2]VENOUS is greater than [CO2]ARTERIAL

4) Most CO2 is transported in the blood in the form of:

  1. Dissolved gas
  2. Carbaminohemoglobin
  3. Bicarbonate ion
  4. Carboxyhemoglobin
5) Select the correct statement about O2 transport in the blood.
  1. During normal activity, a molecule of Hb returning to the lungs contains one molecule of oxygen
  2. As pH decreases, oxygen's affinity for Hb increases
  3. A 50% oxygen saturation level of blood returning to the lungs might indicate a higher activity level than normal
  4. All of the above
  5. None of the above

6) When carbon dioxide is carried by red blood cells it is carried in part by:

A) the amino acids in globin  
B) integrins in the plasma membrane.
C) nitric oxide.

D) All of these are correct.
 

7) Oxygen is transported by red blood cells by binding to:  

A) specific receptors on the plasma membrane.  
B) specific receptors within the nucleus of the red blood cell.  
C) the beta polypeptide chain of the globin portion of hemoglobin.
D) the polypeptide chain of the heme portion of hemoglobin.  

E) the iron ion in the heme portion of hemoglobin.

8) The binding of oxygen to hemoglobin is characterized as:

  1. Compliant
  2. Irreversible
  3. Reversible
  4. Noncompliant

9) Where would you expect to find the highest partial pressure of carbon dioxide?

A) in the atmosphere
B) in pulmonary arteries
C) in pulmonary veins
D) in alveolar air
E) in the intracellular fluid

10) The reason the gradients for carbon dioxide can be smaller that those for oxygen and still meet the body's gas exchange needs is that:  

A) carbon dioxide is a smaller molecule than oxygen.
B) carbon dioxide is more water‑soluble than oxygen.
C) carbon dioxide receives assistance crossing membranes from a carrier molecule.
D) much of the oxygen, but not the carbon dioxide, is consumed by red blood cells during transport.
E) oxygen forms ions once it enters the alveoli, and the electrical charges slow its movement across membranes.
 

11) Expired air has a greater oxygen content than alveolar air because:  

A) more oxygen diffuses in across the mucosa of the bronchioles and bronchi.
B) newly inspired air is entering as expired as it is leaving.
C) oxygen is being generated by microbes in the upper respiratory tract.
D) alveolar air mixes with air in the anatomic dead space on its way out.
E) some carbon dioxide is converted to oxygen in respiratory passages.
 

12) Most oxygen is transported in blood by:  

A) the heme portion of hemoglobin.
B) the globin portion of hemoglobin.
C) simply dissolving in plasma.
D) conversion to bicarbonate ion.
E) any type of plasma protein.

13) You would expect the partial pressure of oxygen to be highest in the:  

A) pulmonary arteries.
B) pulmonary veins.
C) hepatic portal vein.
D) intracellular fluid.
E) interstitial fluid.
 

14) If the pH of blood and interstitial fluid rises within homeostatic range, then:  

A) more oxygen can combine with hemoglobin.
B) less oxygen can stay attached to hemoglobin.  
C) the level of hydrogen ions in these fluids has increased.  
D) the increase was caused by an elevated partial pressure of carbon dioxide.
E) respiratory rate will increase to compensate.
 

15) To say that hemoglobin is fully saturated means that:  

A) the red blood cells contain as many hemoglobin molecules as possible.
B) oxygen is attached to both the heme and the globin portions of the molecule.
C) it is carrying both oxygen and carbon dioxide simultaneously.
D) some molecule other than oxygen is attached to the oxygen binding sites on hemoglobin.
E) there is an oxygen molecule attached to each of the four heme groups.

16) Which of the following would be TRUE if the oxygen‑hemoglobin dissociation curve is shifted to the right?  

A) Partial pressure of carbon dioxide is increased.
B) pH is increased.
C) Temperature is decreased.
D) Levels of BPG are decreased.
E) Partial pressure of oxygen is decreased.
 

17) In metabolically active tissues you would expect:  

A) the percent saturation of hemoglobin will be less than it is near the lungs.
B) the partial pressure of oxygen will be higher than in the alveoli.
C) the pH will be slightly higher than it is in the fluid close to the lungs.
D) the partial pressure of carbon dioxide will be at its lowest point.
E) All of these are correct.
 

18) If the partial pressure of carbon dioxide is decreasing, then:  

A) the partial pressure of oxygen must be increasing.
B) the pH will also be decreasing.
C) the affinity of hemoglobin for oxygen is decreasing.
D) there is an increase in the rate of the reaction converting carbonic acid into water and carbon dioxide.
E) there is an increase in the rate of the reaction converting carbonic acid into hydrogen ion and bicarbonate ion.

19) BPG is a substance that:

A) is responsible for the detergent activity of surfactant.
B) catalyzes the conversion of carbon dioxide to bicarbonate ion.
C) is produced during glycolysis in erythrocytes and increases the dissociation of oxygen from hemoglobin.
D) inhibits the activity of the central chemoreceptors to prolong inspiration.
E) binds extra oxygen onto fetal hemoglobin.
 

20) Hemoglobin will tend to bind more oxygen at a given partial pressure of oxygen if: 

A) the partial pressure of carbon dioxide is increased.
B) the temperature is increased.
C) the pH is increased.
D) BPG concentration increases.
E) the concentration of hydrogen ions increases.
 

21) High partial pressure of carbon dioxide favors the formation of:  

A) BPG.
B) carbaminohemoglobin.
C) chloride ions.
D) oxyhemoglobin.
E) carbon monoxide.

22) Carbonic acid is produced when:  

A) oxygen combines with bicarbonate ion.
B) carbon dioxide combines with bicarbonate ion.
C) carbon dioxide combines with water.
D) oxygen and carbon dioxide combine.
E) carbon dioxide attached to hemoglobin.
 

23) Most carbon dioxide is transported in blood by:  

A) the heme portion of hemoglobin.
B) the globin portion of hemoglobin.
C) simply dissolving in plasma.
D) conversion to bicarbonate ion.
E) any plasma protein.

COMPLETION

24) As plasma Pco2 increases, plasma pH will ___________.

25) As plasma Pco2 increases, both the rate and depth of respiration will ________________________.

26) As plasma pH decreases, hemoglobin's O2 affinity will _________.

27) You begin to hyperventilate! What happens to your plasma Pco2? What about your plasma pH?

28) In the above question, what acid-base imbalance will likely result, prior to compensation?

29) As blood flows through the pulmonary capillaries, Cl- in the plasma will ________________.

30) Oxygen and carbon dioxide are exchanged through all cell membranes by ____________.


31) The total pressure exerted by a mixture of gasses is (equal to, greater than, lesser than) the sum of the individual partial pressures of gases in the mixture.

32) If you had 10 RBCs each containing 100 molecules of hemoglobin, how many molecules of oxygen could these RBCs transport?

33) When a bicarbonate ion exits a red blood cell, a chloride ion will enter in order to maintain charge balance. This is known as the ________

MULTIPLE CHOICE

34) Partial pressure of oxygen (P02) in blood:

a) refers to the pressure exerted by the amount of oxygen dissolved in the blood
b) is the most important factor determining the percent saturation of hemoglobin
c) is normal in carbon monoxide poisoning
d) both a and b above are correct
e) all of the above are correct

35) P02

a) of atmospheric air averages 20% of total atmospheric pressure
b) of blood is the most important factor that determines the extent to which oxygen will combine with hemoglobin
c) of arterial blood is decreased when hemoglobin preferentially combines with CO rather than oxygen
d) both a and b above are correct
e) all of the above are correct

36) If the alveolar P02 is 100 mm Hg, the blood leaving the pulmonary capillaries in a normal person will have a P02 of:

a) 40 mm Hg
b) 46 mm Hg
c) 100 mm Hg
d) 760 mm Hg
e) none of the above are correct

37) Which of the following would decrease diffusion of a gas across the alveolar/pulmonary capillary membrane?

a) an increase in thickness of the membrane
b) an increase in surface area of the membrane
c) an increase in the partial pressure gradient
d) two of the above are correct
e) all of the above are correct

COMPLETION

38) Systemic venous P02 is ________ alveolar P02 and systemic venous PC02 is _________ alveolar PC02

39) Systemic arterial P02 is ________ tissue P02 and systemic arterial PC02 is _________ alveolar PC02

MULTIPLE CHOICE

40) The percent hemoglobin saturation:

a) decreases as PO2 increases
b) decreases as PCO2 increases
c) decreases as H+ decreases
d) decreases as body temperatures decreases
e) more than one of the above are correct

41) Which of the following will not cause the oxygen-hemoglobin dissociation curve to shift to the right?

a) an increase in PO2
b) an increase in temperature
c) an increase in PCO2
d) an increase in acidity
e) an increase in DPG

42.Oxygen-binding sites on hemoglobin have the highest affinity for: 

(a) carbon dioxide.
(b)
 oxygen.
(c)
 carbon monoxide .
(d) nitrogen

43.Which of the following factors does not shift the Hb-O2 curve to the right?

(a) increased CO2
(b)
 increased CO
(c)
 increased H+
(d)
 increased temperature
(e)
 increased DPG
 

44.Approximately what percent of oxygen is transported in the blood physically dissolved?

      (a) 10%
(b) 30%
(c)
 1.5%
(d) 98.5%
(e)
 60%
 

45.The primary factor determining the percent hemoglobin saturation is:

(a) blood PO2.
(b) blood PCO2.
(c) diphosphoglycerate concentration.
(d) the temperature of the blood.
(e) the acidity of the blood.
 

46. The plateau portion of the O2-Hb curvez:

(a) is in the blood-Po2 range that exists at the pulmonary capillaries.
(b) means that hemoglobin becomes almost nearly saturated in the lings unless the pulmonary capillary P02 falls below 60 mm Hg.
(c) is in the blood-Po2 range that exists at the systematic capillaries.
(d) Both (a) and (b) above are correct.
(e) Both (b) and (c) above are correct.
 

47. Because of the steep portion of the O2-Hb curve,

(a) there is a good margin of safety in O2-carrying capacity of the blood.
(b) a small drop in systematic capillary PO2 in a metabolically active tissue automatically makes large amounts of O2 available, because O2 is released from hemoglobin as a result of a big drop in percent hemoglobin saturation.
(c) O2 loading is still almost normal even when alveolar PO2 falls up to 40%.
(d) more O2 is physically dissolved in the systemic capillaries than in the pulmonary capillaries.
(e) the affinity of hemoglobin for O2 is increased as the blood PO2 decreases.

48. Which of the following statements concerning hemoglobin is(are) correct?

(a) The presence of hemoglobin keeps the blood PO2 low and favors O2 movement into the blood despite a very large transfer of O2 until hemoglobin is completely saturated.
(b) Hemoglobin can combine with O2, CO2, H+ and CO.
(c) Hemoglobin unloads more O2 in the presence of increased tissue acidity.
(d) All of the above are correct.
 

49. Hemoglobin:

(a) combines preferentially with O2 over any other substance.
(b) when combined with carbon dioxide is known as carboxyhemoglobin.
(c) plays a critical role in determining the amount of O2 that is exchange between alveoli and blood, because it acts as a storage depot, removing dissolved O2 from diffusion of O2 to continue until the hemoglobin is completely saturated.
(d) Both (b) and (c) above are correct.
(e) All of the above are correct.
 

50. The amount of oxygen unloaded from hemoglobin at the tissue level increases when:

      (a) PCO2 in the tissue increased.
(b) the concentration of DPG in the red blood cells increases.
(c) the concentration of DPG in the red blood cells decreases.
(d) Both (a) and (b) above are correct.
(e) Both (a) and (c) above are correct.
 

51. The normal percent of hemoglobin in venous blood is:

(a) 97%.
(b) 75%.
(c) 50%.
(d) 40%.
(e) 10%.
 

52. Approximately what percent of carbon dioxide is transported in the blood physically dissolved?

      (a) 5%.
(b) 10%.
(c) 20%.
(d) 30%.
(e) None of the above are correct.
 

53. What is the primary method in which CO2 is transported in the blood?

(a) is found in the reed blood cells.
(b) catalyze the formation of carbonic acid from carbonic dioxide and water.
(c) catalyze the formation of oxyhemoglobin form oxygen and reduce hemoglobin.
(d) As bicarbonate.
(e) As carbonic anhydrate.
 

54. Carbonic anhydrase:

(a) is found in the red blood cells.
(b) catalyzes the formation of carbonic acid from carbonic dioxide and water.
(c) catalyzes the formation of oxyhemoglobin from oxygen and reduce hemoglobin
(d) Both (a) and (b) above are correct.
(e) Both (a) and (c) above are correct.
 

55. 2, 3-diphosphoglycerate:

(a) is produced within red blood cells.
(b) production is inhibited increases whenever HbO2.
(c) concentration gradually increases whenever Hb in the arterial blood is chronically undersaturated.
(d) Both (a) and (b) above are correct.
(e) All of the above are correct.
 

56. Which of the following conditions exist at high altitudes?

(a) Histotoxic hypoxia.
(b) Hypoxic hypoxia.
(c) Anemia hypoxia.
(d) Hypocapnia.
(e) None of the above are correct.
 

57. Hypercapnia:

(a) refers to excess CO2 in the arterial blood.
(b) occurs when CO2 is blown off to the atmosphere at a rate faster than it is being produced by the tissue.
(c) is caused by hyperventilation.
(d) Both (a) and (c) above are correct.
(e) all of the above are correct.
 

58. At high altitudes:

      (a) the alveolar PO2 is higher than normal.
(b) the alveolar PO2 is lower than normal.
(c) the alveolar PCO2 is higher than normal.
(d) Both (a) and (c) above are correct.
(e) Both (b) and (c) above are correct.
 

TRUE-FALSE: For the following use an (A) for TRUE and a (B) for FALSE

59. The 500 ml of air that is inspired is the same 500 ml of air that enters the alveoli during a single breath.
 

60. O2 moves from the alveoli to the blood by active transport.
 

61. The partial pressure of oxygen in blood is a measure of the total content of oxygen in the blood.
 

62. The partial pressure of a gas in blood depends on the amount that physically dissolved and not on the total content of the gas in the blood.

63. Alveolar partial pressure do not fluctuate to any extent between inspiration and expiration.
 

64. The quality of O2 that will diffuse between the alveolar air and pulmonary blood depends solely on the partial pressure gradients that between the alveolar and blood.

65. Alveolar PO2 is greater than systematic venous PO2.

66. Alveolar PO2 is greater than systematic venous PCO2
 

67. Systematic arterial PO2 is greater than tissue PO2.

68. Systematic arterial PCO2 is grater than tissue PCO2.
 

69. A molecule of nitrogen exerts more than pressure than a molecule of oxygen because nitrogen is a larger molecule.
 

70. Alveolar PO2 is higher following inspiration than following expiration.

71. The most important factor that determines the extent to which hemoglobin is saturated with oxygen is the blood PO2.
 

72. O2 is much more soluble in blood than CO2 is.
 

73. At the systematic capillaries, the PO2 is in the range of the steep portion of the O2 –Hb curve.
 

74. Carbonic anhydrase is found only in the plasma.
 

75. During hyperventilation, arterial PCO2 levels decrease because CO2 is blown off more rapidly than it is being produced in the tissue.
 

76. In the plateau region of the Hb-O2 curve, a large decreases in PO2 results ina small decrease in Hb saturation, whereas in the steep portion of the blood and surrounding tissue down PO2 gradients because the O2 bound to Hb does not directly contribute to the blood PO2.
 

77. Hemoglobin, by acting as a storage depot, plays an important role in permitting the transfer of large quantities of O2 between the blood and surrounding tissue down PO2 gradients because the O2 bound to Hb does not directly contribute to the blood PO2.
 

78. The combination of Hb and CO2, is known as carboxyhemoglobin.

COMPLETION

79. The primary factor that determines the % Hb saturation is the __________.      
 

80. The __________ effect refers to the reduced affinity of Hb for O2 in the presence of increased CO2 and H+.        

81. The __________ effect refers to the increased affinity of Hb for CO2 and H+ after O2 unloading.       

82. List the substance that can combine with Hb.    

83. If a person ascended a mountain where the atmospheric pressure was only 500 mmHg, what would the PO2 of the air be, assuming that the air consisted of 21% O2?

84) Which is the most abundant gas in the atmosphere?
 
A) oxygen
 
B) carbon dioxide
 
C) argon
 
D) nitrogen
85) What is the partial pressure of atmospheric oxygen?
 
A) 160 mm Hg
 
B) 21%
 
C) 760 mm Hg
 
D) 0.3 mm Hg
86) What is the normal PCO2 of the capillary blood?
 
A) 0.05 mm Hg
 
B) 45 mm Hg
 
C) 40 mm Hg
 
D) 104 mmHg
87) What is the normal PO2 of the alveolar air?
 
A) 40 mm Hg
 
B) 45 mm Hg
 
C) 104 mm Hg
 
D) 50 mm Hg
88) Where is the highest amount of carbon dioxide found?
 
A) in the air
 
B) in the alveoli
 
C) the arteries entering the lung
 
D) the veins leaving the lung
89) Which condition is characterized by inflammation and infection involving the alveoli?
 
A) ARDS
 
B) tuberculosis
 
C) pneumonia
 
D) atelectasis
90) Most of the oxygen in the blood is found in the _____.
 
A) plasma
 
B) hemoglobin
 
C) iron
 
D) capillaries
91) At high PO2 levels, where is most oxygen located?
 
A) oxyhemoglobin
 
B) hemoglobin
 
C) plasma
 
D) free heme
92) Which of the following factors favors a release of oxygen from hemoglobin?
 
A) decreased CO2
 
B) decreased pH
 
C) lower blood temperature
 
D) increased pH
93) Which of these has the highest affinity for hemoglobin?
 
A) CO2
 
B) nitrogen
 
C) O2
 
D) CO
94) Where is most carbon dioxide transported?
 
A) in the plasma
 
B) as carbaminohemoglobin
 
C) as bicarbonate
 
D) on the heme
95) The most important factor that allows the blood to carry carbon dioxide in high amounts is _____.
 
A) pressure
 
B) tissue production
 
C) carbonic anhydrase
 
D) hemoglobin affinity
96) The respiratory membrane, across which gases diffuse, is very thin and is made up of _______________.
 
A) alveolar macrophages and the alveolar cell membrane
 
B) alveolar cell membrane and its basement membrane
 
C) alveolar cell membrane and capillary membrane
 
D) alveolar cell membrane, capillary membrane, and fused basement membranes
97) Whether oxygen diffuses from the alveoli into the blood or not is dependent upon the partial pressure of _______________.
 
A) oxygen in the lungs and in the blood
 
B) oxygen in the lungs only
 
C) oxygen and carbon dioxide in the blood
 
D) all gases in the atmosphere and blood
98) Within the blood, oxygen is primarily transported __________________ while the bulk of carbon dioxide is transported _________________.
 
A) in association with hemoglobin; as carbon dioxide, dissolved in the plasma
 
B) as deoxyhemoglobin; as carbaminohemoglobin
 
C) as oxyhemoglobin; as bicarbonate ions
 
D) dissolved in the plasma; as carbaminohemoglobin


 

99) In order to maintain homeostasis, chloride ions follow as bicarbonate moves out of the erythrocyte.
 
A) True
 
B) False
100) The main purpose for cellular oxygen is to provide a means of producing most of the cell energy.
 
A) True
 
B) False


 

101) If the alveolar partial pressure of carbon dioxide were 45 mm Hg, carbon dioxide would not readily diffuse into the air.
 
A) True
 
B) False
102) The PO2 in the pulmonary veins is less than the PO2 in the alveolar air.
 
A) True
 
B) False


 

103) At high altitudes it is difficult to breathe because the air has a lower percentage of oxygen.
 
A) True
 
B) False
104) Oxygen dissociates faster from hemoglobin during exercise.
 
A) True
 
B) False
105) Carbon dioxide and oxygen compete for binding sites with the hemoglobin.
 
A) True
 
B) False