Pulmonary blood flow, gas exchange and transport 1

Question 1

Do both alveolar ventilation and compliance incline or decline with height from base of lung to the apex?

Answer 1

Decline

Question 2

Bronchial circulation - what is it supplied by? where do these arise?

Answer 2

Nutritive

Supplied via bronchial arteries from systemic arteries

Question 3

Pulmonary circulation - Describe the flow and pressure

Answer 3

Gas exchange

High flow and low pressure - only 25mmHg

Question 4

What does A stand for?

Answer 4

Alveolar

Question 5

What does a stand for?

Answer 5

arterial blood

Question 6

What does v stand for?

Answer 6

mixed venous blood eg pulmonary artery

Question 7

PACO2

Answer 7

Partial pressure of carbon dioxide in aveolar air

Question 8

PaO2

Answer 8

Partial pressure of oxygen in arterial blood

Question 9

What 3 things is the rate of diffusion across the membrane directly proportional to?

Answer 9

Partial pressure gradient
gas solubility
Available surface area

Question 10

What is the rate of diffusion inversely proportional to?

Answer 10

Thickness of the membrane

Question 11

Is oxygen or carbon dioxide more soluble in water?

Answer 11

Carbon dioxide

Question 12

Emphysema and PO2

Answer 12

Destroys alveoli and reduces surface area

PO2 in alveoli is normal/low and blood is low

Question 13

Fibrotic lung disease and PO2

Answer 13

Thick alveolar membrane so low rate of diffusion

Loss of lung compliance effects ventilation. Same values as emphysema

Question 14

Pulmonary oedema and PO2

Answer 14

Fluid increases diffusion distance so PO2 in blood low

Question 15

Asthma and PO2

Answer 15

Increased airway resistance and decreased ventilation so low PO2 in alveoli and blood

Question 16

Ventilation

Answer 16

Air getting into the alveoli

Question 17

Perfusion

Answer 17

Local blood flow

Question 18

What are ventilation and perfusion measured in?

Answer 18

L/min

Question 19

What is the distribution of blood flow in lungs influenced by? (2)

Answer 19

Blood pressure

Alveolar pressure

Question 20

Is blood flow directly or inversely related to vascular resistance?

Answer 20

Inversely

Question 21

Base of lung - arterial and alveolar pressure

Answer 21

Arterial is higher so vascular resistance is low

Question 22

Apex of lung - arterial and alveolar pressure

Answer 22

Alveolar is higher so vascular resistance is high

Question 23

Above what rib shows a serious mismatch in blood flow and ventilation? What is done about this?

Answer 23

Rib 3

Auto regulated at apex of lung to correct the ratio

Question 24

If ventilation is greater that perfusion is the ratio greater or less than 1?

Answer 24

Greater

Question 25

If perfusion is greater than ventilation is the ratio greater or less than 1?

Answer 25

Less

Question 26

What happens if PCO2 is high and PO2 is low?

Answer 26

Blood does not get oxygenated and oxygenated blood from other areas is diluted

Question 27

What happens to blood flow and where is it directed when tissue PO2 is low?

Answer 27

Underventilated alveoli arterioles constrict to direct blood flow to better ventilated areas

Question 28

What does high PCO2 do the the bronchi?

Answer 28

Mild bronchodilation

Question 29

Does constriction in response occur in only systemic vessels, pulmonary vessels or both?

Answer 29

Pulmonary only

Question 30

Shunt

Answer 30

The passage of blood through areas of the lung that are poorly ventilated (ventilation<

Question 31

Alveolar dead space

Answer 31

Alveoli that are ventilated but not perfused

Question 32

Physiological dead space

Answer 32

Alveolar DS + Anatomical DS