Deck 8: Oxygen Equilibrium and Transport

Question 1

What is the normal amount of oxygen consumed by the tissues?

A) 250 mL/min
B) 500 mL/min
C) 750 mL/min
D) 1000 mL/min

Answer 1

250 mL/min

Question 2

What is the effect of transfusing banked blood stored with an acid-citrate dextrose anticoagulant?

A) It increases oxygen availability to the tissues.
B) It increases the concentration of 2,3-DPG.
C) It decreases oxygen availability to the tissues.
D) It decreases Hb affinity for availability to the tissues.

Answer 2

It decreases oxygen availability to the tissues.

Question 3

Assuming a concentration of 15 g/dL, what will be the hemoglobin's oxygen-carrying capacity?

A) 20.1 mL/dL
B) 30.1 mL/Dl
C) 40.1 mL/dL
D) 50.1 mL/dL

Answer 3

20.1 mL/dL

Question 4

Which of the following terms describes the unoxygenated hemoglobin?

A) Carboxyhemoglobin
B) Reduced hemoglobin
C) Deoxyhemoglobin
D) Methemoglobin

Question 5

Which of the following are statements related to P₅₀?
I.Normally, a PO₂ of 27 mm Hg produces an SO₂ of 50%.
II.The P₅₀ is a measure of hemoglobin's affinity for oxygen.
III.A normal P₅₀ is accurate when the blood temperature is 37° C, pH is 7.40, and PCO₂ is 40 mm Hg.
IV.Normally, a PO₂ of 47 mm Hg produces an SO₂ of 50%.

A) I, II, III, IV
B) II, III
C) I, II, III
D) II, III, IV

Question 6

How many times the body tissues' resting requirement is oxygen delivery?

A) Two times
B) Three times
C) Four times
D) Five times

Question 7

Under resting conditions, what percentage of the arterial oxygen content is extracted by the tissues?

A) 25%
B) 50%
C) 75%
D) 100%

Question 8

What is the name of the phenomenon associated with the decreased affinity of Hb for oxygen when PCO₂ is high?

A) Haldane effect
B) Bohr effect
C) Fick effect
D) Shift effect

Question 9

Which of the following statements relate to the HbO₂ equilibrium curve?
I.Large PO₂ changes cause small to minimal changes in oxygen content, especially at the extreme flat right end (60 to 100 mm Hg).
II.Small PO₂ changes cause large blood oxygen content changes in the middle, steep portion of the curve (20 to 60 mm Hg).
III.Large PO₂ changes cause large changes in oxygen content at the extreme flatter ends of the curve, especially the flat right end (60 to 100 mm Hg).
IV.Small PO₂ changes cause small blood oxygen content changes in the middle, steep portion of the curve (20 to 60 mm Hg).

A) I, II
B) I, II, III, IV
C) II, III
D) I, II, III

Question 10

What is the effect of a high P₅₀?

A) Hemoglobin's affinity for oxygen is increased.
B) Hemoglobin's affinity for oxygen is decreased.
C) It is beneficial to the tissues.
D) It is detrimental in the alveoli.

Question 11

Which of the following factors affect oxygen delivery to the tissues?
I.Hemoglobin concentration
II.Arterial hemoglobin saturation with oxygen
III.Cardiac output
IV.PCO₂ level

A) I, II, III
B) II, III
C) I, II, III, IV
D) II, III, IV

Question 12

Which of the following statements are true of oxygen transport?
I.Hemoglobin allows whole blood to carry approximately 20 mL of oxygen per 100 mL of blood at the normal arterial PaO₂ of 100 mm Hg.
II.Hemoglobin's capacity to carry oxygen is approximately 67 times more than the capacity of plasma alone when PaO? is 100 mm Hg.
III.A normal cardiac output of 5 L/min delivers approximately 1000 mL of oxygen to the body's tissues each minute.
IV.The amount of oxygen delivered is not enough to meet the tissues' resting requirement.

A) I, II, III
B) III, IV
C) I, II, III, IV
D) II, IV

Question 13

Which of the following are normal values for hemoglobin saturations and oxygen partial pressures?
I.Arterial oxygen saturation (SaO₂) is approximately 97.5%.
II.PO₂ is 100 mm Hg at SaO₂ of 97.5%.
III.Mixed venous oxygen saturation (S O₂) is normally 75%.
IV.P O₂ is 60 mm Hg at S O₂ of 75%.

A) I, III, IV
B) I, II, III, IV
C) II, IV
D) I, II, III

Question 14

What is the normal amount of oxygen delivered to the tissues?

A) 500 mL/min
B) 1000 mL/min
C) 1500 mL/min
D) 2000 mL/min

Question 15

Where is the majority of oxygen in blood?

A) Plasma
B) Erythrocyte
C) Interstitium
D) Heart

Question 16

Which of the following levels of PO₂ is associated with sharp decreases in oxygen saturation and content?

A) <40 mm Hg
B) <60 mm Hg
C) <80 mm Hg
D) <100 mm Hg

Question 17

What is the normal amount of oxygen extracted by the tissues for each 100 mL of blood?

A) 5 mL/dL
B) 10 mL/dL
C) 15 mL/dL
D) 20 mL/dL

Question 18

Which of the following conditions decrease hemoglobin's affinity for oxygen?
I.Increased blood PCO₂
II.Decreased blood pH
III.Increased blood temperature
IV.Decreased blood levels of the organic phosphate 2,3-DPG

A) I, II, III
B) II, III
C) I, II, III, IV
D) II, III, IV

Question 19

Which of the following levels of PO₂ is associated with a significant oxygen content gain?

A) 20-40 mm Hg
B) 40-60 mm Hg
C) 60-80 mm Hg
D) 80-100 mm Hg

Question 20

Which of the following is the conventionally accepted value for hemoglobin's oxygen-carrying capacity?

A) 1.34 mL of oxygen per gram of hemoglobin
B) 1.39 mL of oxygen per gram of hemoglobin
C) 2.34 mL of oxygen per gram of hemoglobin
D) 2.39 mL of oxygen per gram of hemoglobin

Question 21

What is the rationale behind using an FIO₂ of 1.0 to manage patients with acute CO poisoning?

A) An FIO₂ of 1.0 greatly decreases the half-life of HbCO.
B) An FIO₂ of 1.0 greatly increases the half-life of HbCO.
C) An FIO₂ of 1.0 greatly decreases the Hb affinity for CO.
D) An FIO₂ of 1.0 greatly increases the Hb affinity for CO.

Question 22

A patient has the following arterial blood-gas values while breathing room air: PaO₂ = 100 mm Hg; SaO₂ = 0.975.The hemoglobin concentration is 7 g/dL, and the is 8 L/min.Will the resting oxygen consumption be affected?

A) Yes, because hemoglobin is below normal levels.
B) No, because the PaO₂ is normal.
C) No, because the DO₂ is well above the normal resting oxygen consumption.
D) Yes, because the cardiac output is excessively high.

Question 23

Which of the following statements are true of blood transfusion to improve oxygen delivery?
I.It is recommended when DO₂crit is reached.
II.It is associated with increased mortality.
III.It is indicated when hypoxia is due to anemia (Hb of 8 g/dL).
IV.It is associated with increased mortality.

A) I, II, III
B) II
C) II, III
D) II, III, IV

Question 24

Which of the following conditions is an example of hypoxemia with cyanosis?

A) CO inhalation
B) Severe anemia
C) Polycythemia
D) Elevated carboxyhemoglobin

Question 25

What is the minimum desaturated hemoglobin concentration in the capillaries when most observers perceive cyanosis?

A) 5 g/dL
B) 7 g/dL
C) 9 g/dL
D) 11 g/dL

Question 26

What is the clinical consequence of the point below DO₂crit?

A) Initiation of anaerobic metabolism
B) Initiation of aerobic metabolism
C) An increase in cardiac output
D) A decrease in the Hb level

Question 27

What is the best explanation for the presence of peripheral cyanosis?

A) Low venous oxygen saturation
B) High arterial oxygen saturation
C) Low Hb concentration
D) High Hb concentration

Question 28

What is the interpretation of a decrease in the C(a - )O₂?

A) A decrease in the oxygen extraction ratio
B) A reduction in cardiac output
C) An increase in cardiac output
D) A decrease in the Hb level

Question 29

Which of the following statements are true of fetal hemoglobin?
I.Hemoglobin present in the fetus has a high affinity for oxygen.
II.HbF of normal-term infants has a P₅₀ of approximately 22 mm Hg.
III.A cyanotic newborn infant has a much lower arterial PO₂ than an equally cyanotic adult.
IV.By 6 months after birth, most HbF has been replaced with HbA.

A) I, II, III
B) II
C) II, III
D) I, II, III, IV

Question 30

Which of the following are pathological features associated with HbS?
I.Thromboemboli
II.Ischemia
III.Polycythemia
IV.Tissue hypoxia

A) I, II
B) II, IV
C) II, III, IV
D) I, II, IV