PSC1002/L15 Ventilation

Question 1

Define elasticity.

Answer 1

Ability of tissue to return to its original state when stretched

Question 2

Describe PIP between breaths.

Answer 2

Intrapulmonary pressure = atmospheric pressure

Question 3

Describe PIP during inspiration.

Answer 3

Lung volume increases
PIP decreases

Question 4

Describe PIP during expiration.

Answer 4

Lung volume decreases
PIP increases

Question 5

Give the 3 primary physical factors that influence the overall effectiveness of pulmonary ventilation.

Answer 5

Airway resistance
Alveolar surface tension
Lung compliance

Question 6

What is airway resistance determined by? (4)

Answer 6

Length of system
Airway diameter
Flow
Viscosity of gas

Question 7

Which of the airways has the highest resistance?

Answer 7

Bronchi

Question 8

Give 3 conditions which increase the resistance of airways.

Answer 8

Inflammation
Increased mucus secretion
Presence of tumour

Question 9

Describe central control of the bronchial tone. (2)

Answer 9

Parasympathetic innervation of airways
Bronchoconstriction increases resistance

Question 10

Describe non-neural control of airways. (2)

Answer 10

Sympathetic B2 receptors present on SM activated by adrenergic agonists
Bronchodilation decreases resistance

Question 11

Describe the gas-water boundary of the alveoli. (2)

Answer 11

Water molecules form H-bonds
Gases non-polar and no not form H-bonds

Question 12

When is surface tension at its highest and why? (2)

Answer 12

When alveoli are at their smallest diameter during expiration
Increased ST resists ability of alveolus to inflate

Question 13

What is the law of LaPlace? (2)

Answer 13

Small alveoli will be more difficult to inflate than larger alveoli
Surfactant reduces surface tension

Question 14

What does a high amount of unopposed surface tension cause in alveoli?

Answer 14

Collapse during expiration (atelectasis)

Question 15

How does surfactant disrupt the cohesive force of H-bonding in water? (2)

Answer 15

Contains proteins and phospholipids
Polar and non-polar end

Question 16

What does surfactant allow alveoli to do and where is it more concentrated because of this? (2)

Answer 16

Remain partially open even during expiration
In smaller alveoli to increase stability

Question 17

Define lung compliance.

Answer 17

The ability of the chest wall/lungs to stretch/distend

Question 18

What affects lung compliance? (3)

Answer 18

Alveolar surface tension
Distensibility of elastic tissue of lung
Ability of chest wall to move or stretch during inspiration

Question 19

How does emphysema affect lung compliance? (2)

Answer 19

Shift to left
Increased lung compliance

Question 20

How does fibrosis affect lung compliance? (2)

Answer 20

Shift to right
Decreased lung compliance

Question 21

What is forced vital capacity (FVC)?

Answer 21

Maximum inspiration followed by maximum expiration as fast as possible

Question 22

What if FEV1?

Answer 22

Forced expiratory volume in 1 second
First second of forced expiration

Question 23

What is a normal FEV1/FVC value?

Answer 23

80%

Question 24

What effect does restrictive lung disease have on FVC and FEV1?

Answer 24

FVC reduced
FEV1 close to normal

Question 25

What effect does obstructive lung disease have on FVC and FEV1?

Answer 25

FVC close to normal
FEV1 reduced