Ventilation perfusion mismatch

Question 1

Which factor is predominantly responsible for highly efficient gas exchange?

1. large surface area
2. speed of blood flow
3. high conc. inhaled O2
4. all of the above

Answer 1

1. Large surface area

Question 2

Where in the lungs does blood flow at the highest pressure? Why?

Answer 2

The bottom due to gravity. (zone 3)

Question 3

Order the following from highest to lowest pressure in zone 1:
alveolar, venous, arterial

Answer 3

alveolar, arterial, venous

Question 4

Order the following from highest to lowest pressure in zone 2:
alveolar, venous, arterial

Answer 4

arterial, alveolar, venous

Question 5

Order the following from highest to lowest pressure in zone 3:
alveolar, venous, arterial

Answer 5

arterial, venous, alveolar

Question 6

In zone 1 what is blood flow determined by?

Answer 6

alveolar and arterial pressure

Question 7

What is zone 1 also known as?

Answer 7

Alveolar dead space

Question 8

What is zone 2 also known as

Answer 8

Recruitment zone

Question 9

What is blood flow determined by in zone 2?

Answer 9

difference in arterial and alveolar pressure

Question 10

What would be the implication of a haemorrhage on zone 2?

Answer 10

Arterial pressure may drop to below alveolar pressure and it would become like zone 1

Question 11

What is zone 3 also known as?

Answer 11

The distension zone

Question 12

What is blood flow determined by in zone 3?

Answer 12

difference between arterial and venous pressure

Question 13

Which lung region has the largest alveoli? Why?

Answer 13

Zone 1 because gravity compresses the lower ones.

Question 14

Which alveoli can expand more?

Answer 14

Basal

Question 15

What is the ideal ventilation to perfusion (V/Q) ratio?

Answer 15

1

Question 16

What does the ventilation to perfusion ratio vary from throughout the lungs?

Answer 16

3.3 at the apex, 0.6 at the base

Question 17

What is the normal average V:Q ratio?

Answer 17

0.8

Question 18

What is dead space?

Answer 18

Ventilation good, poor perfusion so V:Q very high.

Question 19

What are the three types of dead space?

Answer 19

Physiological (part of each breath that does not take part in gas exchange) (anatomical + alveolar)
Anatomical (the conducting portion of the respiratory tract as gas exchange does not occur here- cannot change)
Alveolar (underperfused alveoli)

Question 20

What condition can cause a large area of dead space?

Answer 20

Pulmonary embolism

Question 21

What is shunt?

Answer 21

Poor ventilation but good perfusion. V:Q very low. Blood having passed through the lungs and failing to be oxygenated.

Question 22

Which condition can cause shunt?

Answer 22

Pneumothorax