Blood Supply, Gas Exchange, Ventillation & Perfusion

Question 1

What is the partial pressure of 02 and C02 in venous circulation?

Answer 1

02 = 40mmHg (5.3)
C02 = 46mmHg (6.2)

Question 2

What does Pa02 stand for?
What does PA02 stand for?
What does Pv02 stand for?

Answer 2

Pa02 = partial pressure of oxygen in arterial blood
PA02 = partial pressure of oxygen in alveolar air
Pv02 = partial pressure of oxygen in mixed venous blood (pulmonary artery)

Question 3

The rate of diffusion across the membrane is directly proportional to the …..

Answer 3

Partial pressure gradient
Gas solubility
Available surface area

Question 4

The rate of diffusion is inversely proportional to…..

Answer 4

The thickness of the membrane

Question 5

From the alveoli to pulmonary arterial blood, what is the pressure gradient of 0xygen?

Answer 5

100mmHg —-> 40mmHg

Question 6

From pulmonary arterial blood to alveoli what is the partial pressure gradient of C02?

Answer 6

46mmHg to 40mmHg

Question 7

At the base of the lung, why Is resistance low?

Answer 7

At the base, blood flow is high because arterial pressure exceeds alveolar pressure and vascular resistance is therefore low

Question 8

At the apex why is resistance high?

Answer 8

At the apex the blood flow is low because the alveolar pressure exceeds the arterial pressure so this compresses arterioles therefore increasing resistance.

Question 9

Where does majority of mismatch occur in the lung?

Answer 9

The apex

Question 10

When ventilation > blood flow, there is
A) increase in alveolar P02
B) increase in alveolar PC02
C)decrease in alveolar P02
D) decrease in alveolar PC02

Answer 10

This is the opposite to shunt and is an example of anatomical dead space.
It results in an increase in alveolar 02 and a decrease in alveolar PC02

Question 11

Does an increase in alveolar P02 cause pulmonary vasodilation or vasoconstriction?

Answer 11

Vasodilation

Question 12

Does an increase in alveolar PC02 cause bronchoconstriction or bronchodilation?

Answer 12

Bronchodilation

Question 13

What is shunt?

Answer 13

A term which describes the passage of blood through areas of lung that are poorly ventilated
Where perfusion > ventilation

Question 14

What is the term for alveoli which are ventilation but not perfused?

Answer 14

Alveolar dead space

Question 15

What is the physiological dead space?

Answer 15

Alveolar dead space + anatomical dead space

Question 16

Why does C02 diffuse more rapidly?

Answer 16

It has greater solubility

Question 17

C02 diffuses more rapidly, therefore how does the diffusion of C02 and 02 remain in equilibrium?

Answer 17

There is a greater pressure difference for 02

Question 18

what is term used to describe anatomical dead space + alveolar dead space?

Answer 18

physiological dead space

Question 19

what is alveolar dead space defined as?

Answer 19

alveoli which are ventilated but not perfused