Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Respiratory Physiology > Ventilation and Compliance > Flashcards

Ventilation and Compliance Flashcards

1
Q

Define tidal volume and state the normal TV

A

Volume of air breathed in and out in one breath

500ml

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Define expiratory reserve volume and state normal ERV

A

Maximum volume of air expelled from lungs at end of normal expiration
1100ml

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Define inspiratory reserve volume and state normal IRV

A

Maximum volume of air able to draw into lungs at the end of a normal inspiration
3000ml

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Define residual volume and state normal RV

A

Volume of gas lift in lungs at end of normal inspiration

1200ml

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Define vital capacity and state normal VC

A

TV+ERV+IRV

4600ml

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Define total lung capacity and state normal TLC

A

VC+RV

5800ml

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Define inspiratory capacity and state normal IC

A

TV+IRV

3500ml

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Define functional residual capacity and state normal FRC

A

ERV+RV

3300ml

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Define FEV1

A

Forced Expiratory Volume in one second

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Define FEV1/FEV

A

Fraction of FEV expired in 1 second

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Define pulmonary (minute) ventilation

A

Movement of air in and out lungs

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Define alveolar ventilation and how it is measured

A

Fresh air available to alveoli and thus exchanged.

Measured in L/min

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Explain the concept of anatomical dead space and alveolar ventilation in terms of volumes

A

The air in airways above alveoli is stale air and only the air in alveoli is exchanged.
For every 500ml of air, 350mls is fresh air that is exchanged and 150mls is stale air in the anatomical dead space

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

State how alveolar ventilation is calculated

A

(Tidal Volume - 150) x Respiratory Rate

NEED TO DIVIDE BY 1000 TO GET IN L/min

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Calculate normal ventilation

A

(500-150) x 12 = 4200 = 4.2L/min

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Calculate hypoventilation if respiratory rate is 20 breaths per minute and tidal volume is 300ml

A

(300-150) x 20 = 3000 = 3 L/min

17
Q

Calculate hyperventilation if RR is 8 breaths per minute and tidal volume is 750ml

A

(750-150) x 8 = 4800 = 4.8L/min

18
Q

Define partial pressure

A

The pressure of gas in gas mixture equivalent to the percentage of that gas in that mixture multiplied by the pressure of the whole gas mixture.
E.g. if 21% of a mixture is O2 and the pressure of the whole mixture is 760mmHg then the partial pressure of O2 in that mixture will be 160mmHg

19
Q

What is the consequence of all gas molecules exerting the same pressure?

A

This means that pressure increases if the concentration of gases in a mixture increases.

20
Q

Define normal atmospheric PO2 and normal alveolar PO2

A 
Atmospheric = 160mmHg
Alveolar = 100mmHg
21
Q

Define normal alveolar PO2 and normal alveolar PCO2 in mmHg and pKa which are mirrored in arterial blood

A 
PO2 = 100mmHg / 13.3pKa
PCO2 = 40mmHg / 5.3pKa
22
Q

State the partial pressures of O2 and CO2 in hypo and hyperventilation in mmHg

A

HYPOVENTILATION
PO2 = 30mmHg PCO2 = 100mmHg

HYPERVENTILATION
PO2 = 120mmHg PCO2 = 100mmHg

23
Q

What is surfactant?

A

Detergent like substance made by Type II alveolar cells

Reduces surface tension.

24
Q

Define surface tension and state it’s effect on alveoli

A

Surface tension is the attraction of water molecules together when there is a water-air interface.
This creates an inwardly directed pressure which causes the alveoli to collapse

25
Q

Describe how surfactant reduces the work of breathing

A

Surfactant reduces surface tension thus increasing compliance and reducing the tendency of the lungs to recoil (and the alveoli collapsing)

26
Q

Why is surfactant more effective in small alveoli?

A

Surfactant is more effective in small alveoli because surfactant molecules are closer together making it more concentrated.

27
Q

How does the Law of LaPlace explain why air is more likely to flow into large, as opposed to small alveoli?
How does surfactant equalise this?

A

Law of LaPlace P=2T/r which means that pressure is greater in the smaller alveolus because the radius is less. This means that air is more likely to flow into larger alveoli at a lower pressure which reduces the SA that can absorb air.
Surfactant lowers the surface tension making the smaller alveoli easier to inflate by reducing their tendency to recoil.

28
Q

Define compliance

A

Change in volume relative to the change in pressure.

The stretchability of the lungs

29
Q

When is compliance high?

A

When there is a large increase in volume for a small decrease in intrapleural pressure

30
Q

When is compliance low?

A

When there is a small increase in volume for a large decrease in in intrapleural pressure

31
Q

Why is a greater change in pressure from required in inflate the lungs in comparison to deflating them?

A

Because the surface tension needs to be overcome during inspiration

32
Q

What is the effect of restrictive lung diseases on compliance

A

Fibrosis reduces compliance

33
Q

What is the effect of obstructive lung disease such as emphysema on compliance?

A

Loss of surface tension due to alveolar loss leads to highly compliant but expiration is much more difficult

34
Q

Define the normal FEV1 to FVC ratio

A

4/5=80%

35
Q

Describe the FEV1 to FVC ratio in obstructive lung disease

A

1.3/3.1=43%
Airway resistance is increased so air is obstructed on expiration.
Air gets out much more slowly so FEV1 is reduced. FVC is also reduced to a greater extent and FRC will be higher

36
Q

Describe the FEV1 to FVC ratio in restrictive lung disease

A

2.8/3.1 =90%
Difficulty in lung expansion due to fibrosis.
Lack of surfactant means that the total volume is reduced and large volume can’t be expelled in 1 second so the ratio stays the same. This is a limitation of spirometry

37
Q

Define forced expiratory flow (FEF25-75)

A

Air expired in 1 second in middle of FVC. Correlates with FEV1 but changes more striking.

38
Q

List the three factors that determine compliance

A

Elastic forces
Surface tension at alveolar air-liquid interface
Airway resistance

39
Q

How do ventilation and compliance vary from apex to base?

A

At the base of the lung the volume change is greater for a given change in pressure
Alveoli are also more compliant at the base of the lung than at the apex because they are more compressed between the weight of the lung and the diaphragm meaning a small change in ip pressure will have the greatest effect on volume here.

Respiratory Physiology (6 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions