#1 Zhu - Principles of Pulmonary Gas Transport

Question 1

What does Fick’s law measure?

What are the 5 components of Fick’s law?

Answer 1

DIFFUSION RATE
Pressure Gradient
Area
Solubility (Intrinsic property of gas)
Distance
Molecular Weight
FICK = FIVE

Question 2

Which components of Fick’s law are inversely related to the diffusion rate?

Answer 2

Distance

Molecular Weight

Question 3

What is the diffusion constant?

Answer 3

Solubility/(sqrt of Molecular Weight)

Question 4

What does the diffusion capacity determine?

Answer 4

The diffusion capacity determines the ability of the respiratory membrane to transport a gas into and out of the blood.

Question 5

What are the components of the diffusion capacity?

Answer 5

Area
Solubility
Distance
Molecular Weight
It can change due to change in area and/or change in distance.

Question 6

Where does gas exchange happen?

Answer 6

Respiratory Unit

• Respiratory Bronchioles
• Alveolar Duct
• Alveolar Sac

Question 7

In emphysema, what would you expect to happen to the diffusion rate and why?

Answer 7

Decreased diffusion rate due to decreased area.

Question 8

In interstitial edema, what would you expect to happen to the diffusion rate and why?

Answer 8

Decreased diffusion rate due to increased distance.

Question 9

In fibrosis, what would you expect to happen to the diffusion rate and why?

Answer 9

Decreased diffusion rate due to increased distance.

Question 10

What is the vapor pressure based on a body temperature of 37 degrees Celsius?

Answer 10

47 mmHg

Question 11

What is the PO2 of humidified air?

Answer 11

150 mmHg

(760-47) * 0.21

Question 12

What is the PN2 of humidified air?

Answer 12

563 mmHg

(760-47) *0.79

Question 13

What is the PO2 of alveolar air?

Answer 13

104 mmHg

Question 14

What is the PCO2 of alveolar air?

Answer 14

40 mmHg

Question 15

What is the PO2 in the arterial end of the capillary in the lung?

Answer 15

40 mmHg

Question 16

What is the PO2 in the venous end of the capillary in the lung?

Answer 16

104 mmHg

Question 17

What is the PO2 in the systemic arteries and why?

Answer 17

95 mmHg

Bronchial Circulation contamination

Question 18

What is the PO2 in the arterial end of the capillaries in the peripheral tissue?

Answer 18

95 mmHg

Question 19

What is the PO2 in the venous end of the capillaries in the peripheral tissue?

Answer 19

40 mmHg

Question 20

How is O2 transported in the blood?

Answer 20

Dissolved (3%)

Hemoglobin (97%)

Question 21

Hemoglobin F causes what kind of shift in the Oxygen-Hemoglobin Dissociation Curve?

Answer 21

Left shift
Easier to load O2
Increased Affinity

Question 22

Hemoglobin S causes what kind of shift in the Oxygen-Hemoglobin Dissociation Curve?

Answer 22

Right shift
Easier to UNload O2
Decreased Affinity

Question 23

A right shift in the Oxygen-Hemoglobin Dissociation Curve can be induced by?

Answer 23

1 - Increased H+
2 - Increased CO2
3 - Increased temperature
4 - Increased BPG (end product of RBC metabolism, increased in chronic hypoxia)

Question 24

A left shift in the Oxygen-Hemoglobin Dissociation Curve can be induced by?

Answer 24

1 - Decreased H+
2 - Decreased CO2
3 - Decreased temperature
4 - Decreased BPG

Question 25

What is the Bohr Effect and its components?

Answer 25

The Bohr Effect influences the binding of O2. H+ CO2

Question 26

What is the PCO2 at the arterial end of the pulmonary capillary?

Answer 26

45 mmHg

Question 27

What is the PCO2 at the venous end of the pulmonary capillary?

Answer 27

40 mmHg

Question 28

What is the PCO2 at the arterial end of the capillary in the peripheral tissue?

Answer 28

40 Hg

Question 29

What is the PCO2 at the venous end of the capillary in the peripheral tissue?

Answer 29

45 mmHg

Question 30

How is CO2 transported in the blood?

Answer 30

Dissolved (7%) Hemoglobin (23%) HCO3 (70%)

Question 31

What maintains the electrical neutrality in the RBC when HCO3 diffuses out of the RBC?

Answer 31

Cl- diffusing into the RBC | This is referred to as the chloride shift.

Question 32

How would exercise change the chloride shift?

Answer 32

increase

Question 33

How do you calculate the alveolar ventilation?

Answer 33

Ventilation = Frequency (Tidal volume - Dead space) | 4200 mL = 12 (500-350)

Question 34

What determines the PO2 and PCO2 in alveolar air?

Answer 34

1. Alveolar ventilation | 2. Rate of O2 absorption and CO2 excretion

Question 35

Describe the Haldane Effect.

Answer 35

Deoxygenation of the blood increases its ability to carry CO2.

Question 36

What is the ventilation-perfusion ratio?

Answer 36

Alveolar Ventilation / Cardiac Output | 4.2 L/min / 5.0 L/min = 0.8

Question 37

When ventilation exceeds blood flow, the ventilation-perfusion ratio is (less than/greater than) 0.8.

Answer 37

``` Greater than 0.8 The space (the volume of air) does not participate in gas exchange. ```

Question 38

What physiological factors would create a ventilation-perfusion ratio > 0.8? Pathophysiological?

Answer 38

Physiological: upper part of the upright lung Pathophysiological: Obstruction or loss of blood flow

Question 39

What physiological factors would create a ventilation-perfusion ratio less than 0.8? Pathophysiological?

Answer 39

Physiological: lower part of the upright lung Pathophysiological: Obstruction to air flow

Question 40

When blood flow exceeds ventilation, the ventilation-perfustion ratio is (less than/greater than) 0.8?

Answer 40

Less than 0.8 | "Blood enters the arterial system without going through ventilated areas of the lung."