Pulmonary Physiology

Question 1

Mixed venous blood (mmHg)

Answer 1

PO₂ = 40

PCO₂ = 46

Question 2

Alveolar (mmHg)

Answer 2

P_AO₂ = 100

P_ACO₂ = 40

Question 3

Arterial (mmHg)

Answer 3

P_aO₂ = 100 (95)

P_aCO₂ = 40

Question 4

Gas Exchange dependent upon… (3)

Answer 4

-Alveolar ventilation

(P_aCO₂ ~ VCO₂ / V_A)

-Diffusion

(Fick’s Law)

-Alveolar perfusion

Question 5

Oxygen Transportation forms

Answer 5

• Physically dissolved in plasma (2%)
• Chemically combined with Hb (98%)

Question 6

Definition:

• Oxygen content
• Oxygen capacity
• Oxygen saturation

Answer 6

• total amount of oxygen in the blood
• max amount of oxygen that can be combined with Hb
• % of oxygen binding sites bound to O2

(=HbO2 content/HbO2 capacity x100)

Question 7

Oxyhemoglobin dissociation curve (formula)

• shifting right =?
• shifting left = ?

Answer 7

O2 + Hb <-> HbO2

• curve shift right = decreased affinity for O2
• curve shift left = increased affinity for O2

Question 8

CO2 transportation forms

Answer 8

• Dissolved in blood (5-10%)
• Dissolved as bicarbonate (60%)
• Combined with Hb (30%)

Question 9

5 causes of hypoxemia

(A-a, supplemental O2)

Answer 9

• low inspired O2, normal, yes
• hypoventilation, normal, yes
• diffusion abnormality, elevated, yes
• shunting, elevated, no
• V/Q mismatch, elevated, yes

Question 10

Oxygen carrying capacity eqn

Answer 10

about 20 ml in adult

15g Hb x 1.34 mL O2/Hb = 20 mL O2/100mL blood

Question 11

Oxygen content eqn

Answer 11

CaO2 = [Hb x 1.34 x SaO2%] + [PaO2 x 0.003]