3.6.2. Respiratory System Mechanics

Question 1

Static lung mechanics - relationships between pressure and _______ of the lung

Answer 1

Static lung mechanics - relationships between pressure and volume of the lung

Question 2

What are the four lung volumes?

Answer 2

Tidal Volume (TV)

Inspiratory Reserve Volume (IRV)

Expiratory Reserve Volume (ERV)

Residual Volume (RV)

Question 3

What are the four lung capacities?

Answer 3

Inspiratory Capacity (IC)

Functional Residual Capacity (FRC)

Vital Capacity (VC)

Total Lung Capacity (TLC)

Question 4

What is Tidal Volume? (Definition)

Answer 4

Volume exchanged in normal breathing

Question 5

What is Inspiratory reserve volume (IRV)?

Answer 5

Volume maximally inspired above TV

Question 6

What is Expiratory reserve volume (ERV)?

Answer 6

Volume maximally inspired below TV

Question 7

What is Residual volume (RV)?

Answer 7

Volume remaining in lungs that cannot be exhaled

Question 8

What is Total lung capacity (TLC)?

Answer 8

Sum of all of the volumes

Question 9

What is Functional reserve capacity (FRC)?

Answer 9

Volume remaining in lungs after tidal exhalation

Question 10

What is Vital capacity (VC)?

Answer 10

Sum of TV, IRV and ERV

Question 11

What is Forced vital capacity (FVC)?

Answer 11

Volume of air forcibly expelled

Question 12

How can you remember the Lung Volumes?

Answer 12

LITER

Also notice that a capacity is a sum of at least 2 volumes

Question 13

What is the difference in obstructive vs restrictive lung disease in terms of FEV₁/FVC?

Question 14

What do we see with Emphysema in terms of damage to the lungs? Is this an obstructive or restrictive lung disease?

Answer 14

1. degradation of the elastic matrix
2. enlarged alveoli
3. loss of recoil; can’t generate pressure to expel air

Obstructive!

1. results in a degraded lung that cannot resist the pull of the chest [lung volume \> normal level]​

Question 15

What do we see with Pulmonary fibrosis in terms of tissue damage? Is it obstructive or restrictive?

Answer 15

increased fibrotic material

increased compliance - can’t inflate lungs due to chest wall restriction

chest wall has degraded “spring” [lung volume < normal level]

RESTRICTIVE!

Question 16

How does the lung behave with regards to compliance with volume vs. pressure?

Question 17

Compliance is defined as the _____ of the volume/pressure curve

Answer 17

Compliance is defined as the slope of the volume/pressure curve

Question 18

How does the total lung capacity (TLC) and Vital Capacity (VC) change with emphysema and fibrosis (2 answers)

Question 19

________ helps to reduce surface tension and prevent alveoli from collapsing on themselves (atelectasis)

Answer 19

Surfactant helps to reduce surface tension and prevent alveoli from collapsing on themselves (atelectasis)

Question 20

The law of LaPlace states that (what is the equation)?

Answer 20

The law of LaPlace states that P=2T/r

Question 21

The law of LaPlace states that … (word definition)

Answer 21

increased surface tension increases the pressure required to expand the lungs

Question 22

Why do we need to maintain a FRC (Functional Residual Capacity)?

Answer 22

Pressure required to expand smaller alveoli is higher than the pressure required to expand large ones

Question 23

The lung is inflated by changes in pressure in the alveolar and pleural spaces relative to the ________ pressure

Answer 23

The lung is inflated by changes in pressure in the alveolar and pleural spaces relative to the atmospheric pressure

Question 24

pleural pressure should be less than the ________ pressure to introduce air into the lungs

Answer 24

pleural pressure should be less than the alveolar pressure to introduce air into the lungs

Question 25

a pneumothorax causes an ________ in pleural pressure, [resulting in decreased transmural pressure (internal surface pressure - external surface pressure) which will cause a collapsed lung and decrease the elastic properties and decrease the FRC

Answer 25

a pneumothorax causes an increase in pleural pressure, [resulting in decreased transmural pressure (internal surface pressure - external surface pressure) which will cause a collapsed lung and decrease the elastic properties and decrease the FRC

Question 26

Dynamic lung mechanics - relationships between pressure and ________ in the lung

Answer 26

Dynamic lung mechanics - relationships between pressure and flow in the lung

Question 27

Describe how airway resistance alters dynamic lung compliance.

(4 points to discuss)

Answer 27

1. Resistance drops as area increases
2. Airway resistance is greatest in mid-sized airways
3. In small airways, the Cumulative Total cross-sectional area is very large due to their parallel arrangement, which lowers the resistance
4. Pressure drives flow; P1V1=P2V2

Question 28

What are the various pressures in the thoracic cavity when there is no inspiration/expiration? (no air moving)

transmural pressure =?

transpulmonary pressure = ?

P_alveolar = ?

etc.

Question 29

When the airway is closed, there is a positive transmural pressure which (opposes/enables) the expansion of the lungs and prevents inspiration

Answer 29

When the airway is closed, there is a positive transmural pressure which opposes the expansion of the lungs and prevents inspiration

Question 30

What do the pressures in the thoracic cavity look like during inspiration?

Question 31

Draw the flow vs. volume curve for inspiration. How does the flow change throughout inspiration?

Question 32

Draw the flow vs. volume curve for expiration. When does airflow reach its peak? Are the intrathoracic airways narrowing or widening?

Question 33

resistance in the airways is inversely proportional to airway ______ to the fourth power (just as with blood flow)

Answer 33

resistance in the airways is inversely proportional to airway radius to the fourth power (just as with blood flow)

Question 34

_______ flow also increases airway resistance

Answer 34

turbulent flow also increases airway resistance

Question 35

______ is an obstructive disease in which inspiration is impaired

Answer 35

Asthma is an obstructive disease in which inspiration is impaired

Question 36

_______ is an obstructive disease with increased lung compliance; expiration is impaired

Answer 36

COPD is an obstructive disease with increased lung compliance; expiration is impaired

Question 37

A _______ is a restrictive disease with decreased lung compliance and impaired inspiration

Answer 37

A fibrosis is a restrictive disease with decreased lung compliance and impaired inspiration

Question 38

How do FEV₁, FVC, FEV₁/FVC, and FRC change between normal lung, asthma, COPd, and fibrosis?

Question 39

During forced expiration, the reversal of the pressure gradient may result in a drop of airway pressure to where it is equal to the _______ pressure (equal pressure point)

Answer 39

During forced expiration, the reversal of the pressure gradient may result in a drop of airway pressure to where it is equal to the pleural pressure (equal pressure point)

Question 40

How can people make their airway restrictive during forced exhalation in COPD?

Answer 40

a - end inspiration; b - quiet expiration; c - forced expiration

Question 41

How does the flow vs. volume chart change for COPD?

Question 42

How does the flow vs. volume chart change for people with fibrotic disease?