Pulmonary Blood Flow, Gas Exchange and Transport 1

Question 1

What vessels supply the bronchial circulation?

Answer 1

Bronchial arteries

Question 2

What circulatory system gives rise to the bronchial circulation?

Answer 2

Systemic

Question 3

What is the function of the bronchial circulation?

Answer 3

Supplies airway smooth muscle, nerves and lung tissue with oxygen

Question 4

Why is the Pulmonary circulation referred to as high flow, low pressure?

Answer 4

High flow - entire cardiac output 5L/min flows through it

Low pressure - only has systolic pressure of 25mmHg

Question 5

What force influences a low pressure circulatory system?

Answer 5

Gravity

Question 6

Expand on these abbreviations:

a
A
v
P

Answer 6

a - arterial
A - alveolar
v - venous
P - pressure

Question 7

Therefore what does PaCO2 refer to?

Answer 7

Partial pressure of carbon dioxide in the arteries

Question 8

What is the partial pressure of oxygen in the alveoli and arteries?

Answer 8

100mmHg or 13.3kPa

Question 9

What is the partial pressure of carbon dioxide in the alveoli and arteries?

Answer 9

40mmHg or 5.3kPa

Question 10

What is the partial pressure of venous oxygen?

Answer 10

40mmHg or 5.3kPa

Question 11

What is the partial pressure of venous carbon dioxide

Answer 11

46mmHg or 5.6 kPa

Question 12

What four factors effect the rate of gas exchange?

Answer 12

• Partial pressure gradient
• Gas solubility
• Surface area
• Membrane thickness

Question 13

What partial pressure values reflects gas concentrations in the lungs?

Answer 13

Arterial partial pressures

Question 14

What partial pressures values reflects gas concentrations in tissues?

Answer 14

Venous partial pressures

Question 15

How does fibrotic alveolar membrane decrease the rate of gas exchange?

Answer 15

Thickened membrane

Question 16

How does pulmonary oedema decrease rate of gas exchange?

Answer 16

Increased diffusion distance through fluid

Question 17

How does asthma reduce gas exchange?

Answer 17

Constricted bronchi increase resistance to ventilation

Question 18

What is ventilation?

Answer 18

Air getting to the alveoli

Question 19

What is perfusion?

Answer 19

Local blood flow

Question 20

What is the optimal condition for ventilation and perfusion?

Answer 20

They are equal

Question 21

What two forces influence distribution of blood flow?

Answer 21

Hydrostatic blood pressure and alveolar pressure

Question 22

What is blood flow in the lungs proportional to?

Answer 22

Vascular resistance

Question 23

What trend does blood flow demonstrate in relation to height of the lung?

Answer 23

Decreases with height

Question 24

Why is blood flow in the base of the lung high?

Answer 24

Arterial pressure > alveolar pressure

Therefore vascular resistance is low

Question 25

A decrease in PAO2 in the alveoli causes what to occur?

Answer 25

Arterioles to those under-ventilated alveoli are constricted and blood is diverted to better ventilated ones

Question 26

What does an increase in PACO2 do?

Answer 26

Causes mild bronchodilation

Question 27

What response to hypoxia of the pulmonary system is unique?

Answer 27

Constriction due to hypoxia

Question 28

What is shunting?

Answer 28

Refers to the physiological changes that occur in poorly ventilated areas of the lung (ventilation

Question 29

What is alveolar dead space?

Answer 29

Refers to alveoli that are well ventilated but poorly perfused