Respiratory physiology 2

Question 1

What is tidal volume?

Answer 1

Volume of air inspired/expired in a single breath (500ml)

Question 2

What is the functional residual capacity?

Answer 2

Volume in normal lungs after expiration (2300ml)

Question 3

What is residual volume?

Answer 3

Air in lungs after maximal expiration (1200ml)

Question 4

What is expiratory reserve volume?

Answer 4

Air that can still be breathed out after normal expiration (1100ml)

Question 5

What is inspiratory capacity?

Answer 5

Total amount of air that can be inspired after a normal tidal volume expiration (3500ml)

Question 6

What is inspiratory reserve volume?

Answer 6

Quantity of air that can be forcefully inhaled after a normal tidal volume inhalation (3000ml)

Question 7

What is vital capacity?

Answer 7

The volume of air that the patient can exhale after a maximal inhalation (4600ml)

Question 8

What is total lung capacity?

Answer 8

Total volume of air in lungs (5800ml)

Question 9

What prevents the alveoli from collapsing after expiration?

Answer 9

Residual volume

Question 10

What are the 2 pleural membranes?

Answer 10

Parietal pleura (outer)

Visceral pleura (inner)

Question 11

What is the role of the pleural sac?

Answer 11

Ensures lungs and chest wall stay connected.

Question 12

What prevents the lungs recoiling?

Answer 12

Pleural fluid

Question 13

What causes pneumothorax?

Answer 13

Air entering the pleural sac

Question 14

Why does air move into the lungs when the diaphragm contracts?

Answer 14

Thoracic volume increase which decreases pressure allowing air to move into lungs (gas moves from high to low pressure)

Question 15

How do external intercostal muscles increase thoracic volume?

Answer 15

They ‘lift’ rib cage which increase volume

Question 16

How do internal intercostal muscles decrease thoracic volume?

Answer 16

The ‘pull’ ribs down which decrease volume

Question 17

What is alveolar pressure?

Answer 17

Pressure of air within the lungs ( can be negative or positive depending on atmospheric pressure)

Question 18

What is intrapleural pressure?

Answer 18

Pressure within the pleural cavity (always negative)

Question 19

What is transpulmonary pressure?

Answer 19

Difference between alveolar pressure and intrapleural pressure (almost always positive as intrapleural pressure is always negative)

Question 20

What effect does inspiration and expiration have on intrapleural pressure?

Answer 20

During inspiration intrapleural pressure becomes more negative, and during expiration it becomes more positive.

Question 21

What muscles are required during forced inspiration?

Answer 21

Diaphragm, external intercostals, scalenes, stemocleidomastoids.

Question 22

What muscles are required during forces expiration?

Answer 22

Abdominal muscles, internal intercostals.

Question 23

What is the role of surfactant and how does it work?

Answer 23

To reduce surface tension

It sits in between water molecules to reduce attraction, preventing the collapse of the alveoli

Question 24

What causes surface tension?

Answer 24

Air-water interference

Question 25

At what stage of embryology is surfactant production complete?

Answer 25

36 weeks

Question 26

What causes infant respiratory distress syndrome?

Answer 26

Insufficient quantity of surfactant in premature infants

Question 27

What is compliance of the lungs?

Answer 27

Ability for lungs to expand

Question 28

What is high compliance in the lungs?

Answer 28

High stretchability

i.e lungs will have a large increase in volume for a small pressure change.

Question 29

What is low compliance in the lungs?

Answer 29

Low stretchability

i.e lungs will have a small increase in volume for a large pressure change.

Question 30

Does high compliance represent healthy lungs?

Answer 30

Yes, but only when coupled with high elasticity

Question 31

An example of a condition where lung compliance is low

Answer 31

Pulmonary fibrosis

Question 32

An example of a condition where lung compliance if high, but elasticity is low

Answer 32

Emphysema