Question 1

Why is the presence of carbonic anhydrase in RBCs so crucial for carbon dioxide transport?

Accepted Answer

A)  Forms H2CO3, which is the major buffer for carbon dioxide. 
B)  Drives the hydrolysis reaction that forms HCO3-. 
C)  Forms H2CO3, which is the way the majority of carbon dioxide is transported. 
D)  Without its formation, carbon dioxide could not be excreted at the lungs.

Question 2

What is the normal range of PAO2 - PaO2 for healthy young adults breathing room air?

Accepted Answer

A)  5 to 10 mm Hg 
B)  10 to 20 mm Hg 
C)  20 to 30 mm Hg 
D)  50 to 60 mm Hg

Question 3

When O2 uptake by the tissues is abnormally low, as occurs in certain forms of dysoxia, what would you expect to find?

Accepted Answer

A)  Decreased CaO2 
B)  Decreased CvO2 
C)  Decreased PaO2 
D)  Increased CvO2

Question 4

Which of the following statements is true regarding the Haldane effect?

Accepted Answer

A)  At high SaO2 levels, carbon dioxide more readily forms carbamino compounds. 
B)  At high SaO2 levels, the capacity of blood to hold carbon dioxide decreases. 
C)  At high SaO2 levels, the capacity of blood to hold carbon dioxide increases. 
D)  At low SaO2 levels, the capacity of blood to hold carbon dioxide decreases.

Question 5

At body temperature, how much O2 will physically dissolve in plasma at a PO2 of 40 mm Hg?

Accepted Answer

A)  0.12 ml/dl 
B)  0.20 ml/dl 
C)  0.30 ml/dl 
D)  1.34 g/dl

Question 6

Which of the following would you expect to occur if perfusion to an area of the lung remained constant, but VA to this same area decreased?

Accepted Answer

A)  The PACO2 should fall. 
B)  The HCO3- will fall. 
C)  The PAO2 should fall. 
D)  The ventilation/perfusion ratio () should rise.

Question 7

Under normal physiologic circumstances, how many milliliters of O2 are capable of combining with 1 g of Hb?

Accepted Answer

A)  0.003 ml 
B)  0.450 ml 
C)  0.820 ml 
D)  1.340 ml

Question 8

What is the most common cause of hypoxemia in patients with lung disease?

Accepted Answer

A)  Diffusion defect 
B)  Hypoventilation 
C)  Right-to-left shunt 
D)  mismatch

Question 9

Which of the following would you expect to occur if ventilation to an area of the lung remained constant but perfusion to this same area decreased?
1) The PACO2 should fall.
2) The PAO2 should fall.
3) The  ratio should rise.

Accepted Answer

A) 3 only 
B) 1 and 2 only 
C) 1 and 3 only 
D) 1, 2, and 3

Question 10

In which of the following conditions will erythrocyte concentration of 2,3-DPG be decreased?

Accepted Answer

A)  Anemia 
B)  Banked blood 
C)  High pH 
D)  Hypoxemia

Question 11

Which of the following is true regarding fetal hemoglobin (HbF)?

Accepted Answer

A)  It has a reduced level of 2,3-DPG. 
B)  It is replaced in the first month of life. 
C)  It delivers more O2 to tissues at low PaO2 than normal Hb. 
D)  It has a higher P50 than normal Hb.

Question 12

According to the Bohr effect, when the pH drops, what happens?
1) The affinity of Hb for O2 decreases.
2) The Hb saturation for a given PO2 falls.
3) The Hb saturation for a given PO2 rises.

Accepted Answer

A) 1 and 2 only 
B) 2 only 
C) 2 and 3 only 
D) 1, 2, and 3

Question 13

During normal inspiration, which of the following occurs?

Accepted Answer

A)  Alveoli at the apexes expand less than those at the bases. 
B)  Alveoli at the apexes expand more than those at the bases. 
C)  Alveoli at the bases and apexes expand almost equally. 
D)  Alveoli at the bases expand less than those at the apexes.

Question 14

What is the approximate normal CaO2 - CO2 in a healthy adult at rest?

Accepted Answer

A)  5 ml/dl 
B)  15 ml/dl 
C)  20 ml/dl 
D)  250 ml/dl

Question 15

An area of the lung has no ventilation but is normally perfused by the pulmonary circulation. Which of the following statement(s) is/are correct?
1) Blood exiting the pulmonary capillary will have a PO2 = 40 and a PCO2 = 46.
2) The area represents an alveolar shunt.
3) The  is 0.

Accepted Answer

A) 2 and 3 only 
B) 1 and 3 only 
C) 2 only 
D) 1, 2, and 3

Question 16

Under what conditions will the alveolar PACO2 rise above normal?

Accepted Answer

A)  If both metabolic rate and ventilation increase (e.g., through exercise) 
B)  If carbon dioxide production decreases relative to VA 
C)  If VA decreases relative to carbon dioxide production 
D)  When the patient is febrile

Question 17

The affinity of Hb for carbon monoxide (CO) is approximately how many times greater than its affinity for O2?

Accepted Answer

A)  10 to 50 times greater 
B)  50 to 90 times greater 
C)  100 to 190 times greater 
D)  200 or greater

Question 18

Which of the following gases would diffuse fastest across the alveolar-capillary membrane?

Accepted Answer

A)  Air 
B)  Carbon dioxide 
C)  O2 
D)  Nitrogen

Question 19

What does / mismatch have the biggest impact on?

Accepted Answer

A) Carbon dioxide elimination 
B) Dissolved HCO3- 
C) Oxygenation 
D) pH

Question 20

An area of the lung has no blood flow but is normally ventilated. Which of the following statements are true about this area?
1) The alveolar gas is like air (PO2 = 150; PCO2 = 0).
2) The area represents alveolar dead space.
3) The / is elevated.

Accepted Answer

A) 1 and 2 only 
B) 1 and 3 only 
C) 2 and 3 only 
D) 1, 2, and 3

Exam 12: Gas Exchange and Transport

Why is the presence of carbonic anhydrase in RBCs so crucial for carbon dioxide transport?

What is the normal range of PAO₂ - PaO₂ for healthy young adults breathing room air?

When O₂ uptake by the tissues is abnormally low, as occurs in certain forms of dysoxia, what would you expect to find?

Which of the following statements is true regarding the Haldane effect?

At body temperature, how much O₂ will physically dissolve in plasma at a PO₂ of 40 mm Hg?

Which of the following would you expect to occur if perfusion to an area of the lung remained constant, but V_A to this same area decreased?

Under normal physiologic circumstances, how many milliliters of O₂ are capable of combining with 1 g of Hb?

What is the most common cause of hypoxemia in patients with lung disease?

Which of the following would you expect to occur if ventilation to an area of the lung remained constant but perfusion to this same area decreased? 1) The PACO₂ should fall. 2) The PAO₂ should fall. 3) The ratio should rise.

In which of the following conditions will erythrocyte concentration of 2,3-DPG be decreased?

Which of the following is true regarding fetal hemoglobin (HbF) ?

According to the Bohr effect, when the pH drops, what happens? 1) The affinity of Hb for O₂ decreases. 2) The Hb saturation for a given PO₂ falls. 3) The Hb saturation for a given PO₂ rises.

During normal inspiration, which of the following occurs?

What is the approximate normal CaO₂ - CO₂in a healthy adult at rest?

An area of the lung has no ventilation but is normally perfused by the pulmonary circulation. Which of the following statement(s) is/are correct? 1) Blood exiting the pulmonary capillary will have a PO₂ = 40 and a PCO₂ = 46. 2) The area represents an alveolar shunt. 3) The is 0.

Under what conditions will the alveolar PACO₂ rise above normal?

The affinity of Hb for carbon monoxide (CO) is approximately how many times greater than its affinity for O₂?

Which of the following gases would diffuse fastest across the alveolar-capillary membrane?

What does / mismatch have the biggest impact on?

An area of the lung has no blood flow but is normally ventilated. Which of the following statements are true about this area? 1) The alveolar gas is like air (PO₂ = 150; PCO₂ = 0) . 2) The area represents alveolar dead space. 3) The / is elevated.

Exam 12: Gas Exchange and Transport

Why is the presence of carbonic anhydrase in RBCs so crucial for carbon dioxide transport?

What is the normal range of PAO2 - PaO2 for healthy young adults breathing room air?

When O2 uptake by the tissues is abnormally low, as occurs in certain forms of dysoxia, what would you expect to find?

Which of the following statements is true regarding the Haldane effect?

At body temperature, how much O2 will physically dissolve in plasma at a PO2 of 40 mm Hg?

Which of the following would you expect to occur if perfusion to an area of the lung remained constant, but VA to this same area decreased?

Under normal physiologic circumstances, how many milliliters of O2 are capable of combining with 1 g of Hb?

What is the most common cause of hypoxemia in patients with lung disease?

Which of the following would you expect to occur if ventilation to an area of the lung remained constant but perfusion to this same area decreased? 1) The PACO2 should fall. 2) The PAO2 should fall. 3) The ratio should rise.

In which of the following conditions will erythrocyte concentration of 2,3-DPG be decreased?

Which of the following is true regarding fetal hemoglobin (HbF) ?

According to the Bohr effect, when the pH drops, what happens? 1) The affinity of Hb for O2 decreases. 2) The Hb saturation for a given PO2 falls. 3) The Hb saturation for a given PO2 rises.

During normal inspiration, which of the following occurs?

What is the approximate normal CaO2 - CO2 in a healthy adult at rest?

An area of the lung has no ventilation but is normally perfused by the pulmonary circulation. Which of the following statement(s) is/are correct? 1) Blood exiting the pulmonary capillary will have a PO2 = 40 and a PCO2 = 46. 2) The area represents an alveolar shunt. 3) The is 0.

Under what conditions will the alveolar PACO2 rise above normal?

The affinity of Hb for carbon monoxide (CO) is approximately how many times greater than its affinity for O2?

Which of the following gases would diffuse fastest across the alveolar-capillary membrane?

What does / mismatch have the biggest impact on?

An area of the lung has no blood flow but is normally ventilated. Which of the following statements are true about this area? 1) The alveolar gas is like air (PO2 = 150; PCO2 = 0) . 2) The area represents alveolar dead space. 3) The / is elevated.

What is the normal range of PAO₂ - PaO₂ for healthy young adults breathing room air?

When O₂ uptake by the tissues is abnormally low, as occurs in certain forms of dysoxia, what would you expect to find?

At body temperature, how much O₂ will physically dissolve in plasma at a PO₂ of 40 mm Hg?

Which of the following would you expect to occur if perfusion to an area of the lung remained constant, but V_A to this same area decreased?

Under normal physiologic circumstances, how many milliliters of O₂ are capable of combining with 1 g of Hb?

Which of the following would you expect to occur if ventilation to an area of the lung remained constant but perfusion to this same area decreased? 1) The PACO₂ should fall. 2) The PAO₂ should fall. 3) The ratio should rise.

According to the Bohr effect, when the pH drops, what happens? 1) The affinity of Hb for O₂ decreases. 2) The Hb saturation for a given PO₂ falls. 3) The Hb saturation for a given PO₂ rises.

What is the approximate normal CaO₂ - CO₂in a healthy adult at rest?

An area of the lung has no ventilation but is normally perfused by the pulmonary circulation. Which of the following statement(s) is/are correct? 1) Blood exiting the pulmonary capillary will have a PO₂ = 40 and a PCO₂ = 46. 2) The area represents an alveolar shunt. 3) The is 0.

Under what conditions will the alveolar PACO₂ rise above normal?

The affinity of Hb for carbon monoxide (CO) is approximately how many times greater than its affinity for O₂?

An area of the lung has no blood flow but is normally ventilated. Which of the following statements are true about this area? 1) The alveolar gas is like air (PO₂ = 150; PCO₂ = 0) . 2) The area represents alveolar dead space. 3) The / is elevated.