# Composition Of Alveolar Air

### COMPOSITION OF ALVEOLAR AIR

Q. 1

What is the partial pressure for oxygen in the inspired air?

 A 116 mm Hg B 158 mm Hg C 100 mm Hg D 0.3 mm Hg
Q. 1

What is the partial pressure for oxygen in the inspired air?

 A 116 mm Hg B 158 mm Hg C 100 mm Hg D 0.3 mm Hg
Ans. B

Explanation:

Partial pressure of O2 in inspired air (Pi O2) – 158 mm Hg

Gaseous concentration & its partial pressure in alveoli:
1. Oxygen:
Concentration & partial pressure controlled by,
• Rate of absorption of O2 into blood
• Rate of entry of new O2 into lungs by ventilatory process.
Values:
• Partial pressure of O2 in inspired air (Pi O2)
• 158 mm Hg
• Partial pressure of O2 in alveolar air (PA O2)
• 100 mm Hg
• Calculated by “Alveolar gas equation”.
• Partial pressure of O2 in expired air (PE O2)
• 116 mm Hg

2. Carbon-di-oxide:

• Partial pressure of CO2 in inspired air (Pi CO2)
• 0.3 mm Hg
• Partial pressure of CO2 in alveolar blood (PA CO2)
• 40 mm Hg
• Partial pressure of CO2 in expired air (PE CO2)
• 32 mm Hg

Q. 2

What is the partial pressure for oxygen in the expired air?

 A 116 mm Hg B 158 mm Hg C 100 mm Hg D 0.3 mm Hg
Q. 2

What is the partial pressure for oxygen in the expired air?

 A 116 mm Hg B 158 mm Hg C 100 mm Hg D 0.3 mm Hg
Ans. A

Explanation:

Partial pressure of O2 in expired air (PE O2) – 116 mm Hg

Gaseous concentration & its partial pressure in alveoli:
1. Oxygen:
Concentration & partial pressure controlled by,
• Rate of absorption of O2 into blood
• Rate of entry of new O2 into lungs by ventilatory process.
Values:
• Partial pressure of O2 in inspired air (Pi O2)
• 158 mm Hg
• Partial pressure of O2 in alveolar air (PA O2)
• 100 mm Hg
• Calculated by “Alveolar gas equation”.
• Partial pressure of O2 in expired air (PE O2)
• 116 mm Hg

Q. 3

What is the partial pressure for oxygen in the alveolar air?

 A 116 mm Hg B 158 mm Hg C 100 mm Hg D 0.3 mm Hg
Q. 3

What is the partial pressure for oxygen in the alveolar air?

 A 116 mm Hg B 158 mm Hg C 100 mm Hg D 0.3 mm Hg
Ans. C

Explanation:

Partial pressure of O2 in alveolar air (PA O2) – 100 mm Hg.

Gaseous concentration & its partial pressure in alveoli:
1. Oxygen:
Concentration & partial pressure controlled by,
• Rate of absorption of O2 into blood
• Rate of entry of new O2 into lungs by ventilatory process.
Values:
• Partial pressure of O2 in inspired air (Pi O2)
• 158 mm Hg
• Partial pressure of O2 in alveolar air (PA O2)
• 100 mm Hg
• Calculated by “Alveolar gas equation”.
• Partial pressure of O2 in expired air (PE O2)
• 116 mm Hg

Q. 4

What is the partial pressure for carbon-di-oxide in the alveolar blood?

 A 0.3 mm Hg B 40 mm Hg C 32 mm Hg D 158 mm Hg
Q. 4

What is the partial pressure for carbon-di-oxide in the alveolar blood?

 A 0.3 mm Hg B 40 mm Hg C 32 mm Hg D 158 mm Hg
Ans. B

Explanation:

Partial pressure of CO2 in alveolar blood (PA CO2) – 40 mm Hg.

Carbon-di-oxide:

• Partial pressure of CO2 in inspired air (Pi CO2)
• 0.3 mm Hg
• Partial pressure of CO2 in alveolar blood (PA CO2)
• 40 mm Hg
• Partial pressure of CO2 in expired air (PE CO2)
• 32 mm Hg

Q. 5

What is the partial pressure for carbon-di-oxide in the inspired air?

 A 0.3 mm Hg B 158 mm Hg C 100 mm Hg D 32 mm Hg
Q. 5

What is the partial pressure for carbon-di-oxide in the inspired air?

 A 0.3 mm Hg B 158 mm Hg C 100 mm Hg D 32 mm Hg
Ans. A

Explanation:

Partial pressure of CO2 in inspired air (Pi CO2) – 0.3 mm Hg

Carbon-di-oxide:

• Partial pressure of CO2 in inspired air (Pi CO2)
• 0.3 mm Hg
• Partial pressure of CO2 in alveolar blood (PA CO2)
• 40 mm Hg
• Partial pressure of CO2 in expired air (PE CO2)
• 32 mm Hg.

Q. 6

What is the partial pressure for carbon-di-oxide in the expired air?

 A 0.3 mm Hg B 158 mm Hg C 40 mm Hg D 32 mm Hg
Q. 6

What is the partial pressure for carbon-di-oxide in the expired air?

 A 0.3 mm Hg B 158 mm Hg C 40 mm Hg D 32 mm Hg
Ans. D

Explanation:

Partial pressure of CO2 in expired air (PE CO2) – 32 mm Hg

Carbon-di-oxide:

• Partial pressure of CO2 in inspired air (Pi CO2)
• 0.3 mm Hg
• Partial pressure of CO2 in alveolar blood (PA CO2)
• 40 mm Hg
• Partial pressure of CO2 in expired air (PE CO2)
• 32 mm Hg.