= Blood Supply + Gas Exchange + Lung Pathologies Affecting Diffusion

Question 1

What does the bronchial circulation supply ?

Answer 1

Supplies oxygenated blood via bronchial arteries arising from systemic circulation to lung tissues

Question 2

What % does bronchial circulation comprise of left heart output ?

Answer 2

2%

Question 3

What vessel drains blood to left atrium ?

Answer 3

Pulmonary vein

Question 4

What does the pulmonary circulation consist of ?

Answer 4

L and R pulmonary arteries

Question 5

Where do the left and right pulmonary arteries arise from ?

Answer 5

Right ventricle

Question 6

What does the left and right pulmonary arteries carry ?

Answer 6

Entire cardiac output from RV

Question 7

What does the pulmonary artery supply ?

Answer 7

Dense capillary network surrounding the alveoli

Question 8

Where does the blood return to after supplying the capillary network surrounding alveoli ?

Answer 8

Oxygenated blood is returned to left atrium via pulmonary vein

Question 9

How is the pulmonary circulation described ?

Answer 9

High flow, low pressure system (25/10mmHg)

Question 10

What is the partial pressure of O2 in alveoli ?

Answer 10

100mmHg (13.3kPa)

Question 11

What is the partial pressure of CO2 in alveoli ?

Answer 11

40mmHg (5.3kPa)

Question 12

What do partial pressures in the systemic venous blood reflect ?

Answer 12

What’s happening in our peripheral tissues

Question 13

What do partial pressures in systemic arterial blood reflect ?

Answer 13

What’s happening in our alveoli

Question 14

What does A stand for ?

Answer 14

Alveolar

Question 15

What does a stand for ?

Answer 15

Arterial blood

Question 16

What does ṽ stand for ?

Answer 16

Mixed venous blood (e.g. pulmonary artery)

Question 17

What are the values of PAO2 and PACO2 ?

Answer 17

Alveolar PO2- 100mmHg (13.3kPa)Alveolar PCO2- 40mmHg (5.3kPa)

Question 18

What are the values of PaO2 and PaCO2 ?

Answer 18

Arterial PO2- 100mmHg (13.3kPa)Arterial PCO2- 40mmHg (5.3kPa)

Question 19

What are the values of PṽO2 and PṽCO2 ?

Answer 19

Venous PO2- 40mmHg (5.3kPa)Venous CO2- 46mmHg (6.2kPa)

Question 20

How does the air diffuse across the membranes between the alveoli and the blood circulation ?

Answer 20

Diffusion across the partial pressure gradient

Question 21

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

Answer 21

The gas partial pressure gradient Gas solubility The available surface area

Question 22

What is the rate of diffusion across the membrane inversely proportional to ?

Answer 22

The thickness of the membrane

Question 23

What does gas need to be in, in order to be able to diffuse across the alveolar membrane ?

Answer 23

Gas needs to be in solution

Question 24

What are the solubilities of O2 and CO2 ?

Answer 24

O2- not very soluble CO2- very soluble so van diffuse much faster

Question 25

What gas (CO2 or O2) has the greatest pressure gradient ?

Answer 25

O2

Question 26

Describe the overall rates of equilibrium of CO2 and O2 ?

Answer 26

Similar because of the greater pressure gradient for O2

Question 27

How has the anatomy of the lung adapted to maximise gas exchange ?

Answer 27

Large surface area Minimum diffusion distance Thin cell membranes (type I alveolar cells, capillary)

Question 28

What happens to the surface area of alveoli in emphysema ?

Answer 28

Reduced surface area

Question 29

What are the features of fibrotic lung disease ?

Answer 29

Thickened alveolar membranes slows gas exchangeLoss of lung compliance (decrease) may decrease alveolar ventilation, increase in effort of inspirationDecrease in PO2increase in PCO2

Question 30

What are the features of pulmonary oedema ?

Answer 30

Fluid in interstitial space increases diffusion distanceArterial pCO2 may remain normal due to higher solubility in waterImpact on PO2 in blood

Question 31

What are features of Asthma ?

Answer 31

Increased airway resistance decreases airway ventilation because bronchioles are constricted

Question 32

What are the features of emphysema ?

Answer 32

loss of surface area Major impact on diffusionIncrease in compliance, increase in effort of expirationDecrease in PO2Increase in PCO2

Question 33

When is the rate of diffusion across the membrane most rapid ?

Answer 33

Over small distances