Respiratory physiology 3

Question 1

What is ventilation?

Answer 1

Movement of air in and out of the lungs

Question 2

What is perfusion?

Answer 2

Blood flow reaching alveoli

Question 3

What is alveolar ventilation?

Answer 3

Volume of fresh air that reaches the alveoli

Question 4

How is total pulmonary ventilation calculated?

Answer 4

Tidal volume x respiratory rate

Question 5

Why is the partial pressure of O2 higher in the air than in the alveoli?

Answer 5

Because the fresh air is partially diluted in dead space.

Question 6

What is the normal alveolar partial pressure of O2 and CO2?

Answer 6

PAO2 = 100mmHg

PACO2 = 40mmHg

Question 7

What is the comparison of ventilation at the base and apex of the lungs?

Answer 7

Ventilation is greater at the vase than the apex, this is because at the base the alveoli are ‘squashed’ allowing them to have greater capacity to expand.

Question 8

What is bronchial circulation?

Answer 8

Bronchial arteries provide oxygenated blood to lung tissue

Question 9

What is the comparison of blood pressure in systemic circulation and pulmonary circulation?

Answer 9

Systemic circulation has much higher pressure (120/80 mm Hg) than pulmonary circulation (25/10mmHg)

Question 10

Ideally, what is partial pressure in the alveoli equal to?

Answer 10

Partial pressure in arterial circulation

Question 11

What is the comparison of the partial pressure gradient of O2 and the partial pressure gradient of CO2?

Answer 11

PO2 gradient is 10x greater than PCO2 gradient.

(PO2 - 100 to 40mmHg, PCO2 -46 to 40mmHg)

Question 12

What is more water soluble, CO2 or O2?

Answer 12

CO2

Question 13

Elastic fibres are never located between type 1 alveolar cells and capillary cell, why is this important?

Answer 13

To allow for a short gas diffusion distance

Question 14

What is emphysema?

Answer 14

Destruction of alveoli, reduces surface area for gas diffusion.

Also causes loss of elasticity

Question 15

What is fibrotic lung disease?

Answer 15

Thickened alveolar membrane slows gas exchange

Question 16

What is pulmonary oedema?

Answer 16

Increase in interstitial fluid causes increased diffusion distance

Question 17

What is asthma?

Answer 17

Increased airway resistance caused by constriction of bronchioles, causes decreased ventilation

Question 18

What is the main cause of emphysema?

Answer 18

Smoking

Question 19

What is an obstructive lung disease?

Answer 19

Disease which causes obstruction to air flow (effect expiration)

Question 20

What is restrictive lung disease?

Answer 20

Restriction to lung expansion, caused by loss of compliance (effects inspiration)

Question 21

Give 2 examples of obstructive lung disorders

Answer 21

Asthma

COPD (chronic bronchitis and emphysema)

Question 22

Give 4 example of restrictive lung disorders

Answer 22

IPD

Infant respiratory distress syndrome

Pulmonary oedema

Pneumothorax

Question 23

What piece of equipment can be used to measure lung function?

Answer 23

Spirometer

Question 24

In a healthy young male what is the normal value for FEV1/FVC?

Answer 24

FEV1 - Forced expiratory volume in 1 second, 4l

FVC - forced vital capacity, 5L - FEV1/FVC = 80%

Question 25

What effect does obstructive disorders have on the FEV1/FVC ratio?

Answer 25

Decrease

Question 26

What effect does restrictive disorders have on the FEV1/FVC ratio?

Answer 26

Constant or sometimes increased.