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Respiratory Physiology > Ventilation and Compliance > Flashcards

Ventilation and Compliance Flashcards

1
Q

What is the anatomical dead space defined as?

A

Volume of gas occupied in conducting airways that isn’t exchanged

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2
Q

What is the anatomical dead space volume?

A

Around 150ml

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3
Q

What volume of air is usually inhaled and exhaled per breath at rest (tidal volume)?

A

Around 500ml each way

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4
Q

What is the expiratory reserve volume (ERV) defined as?

A

How much air you can force out after a normal exhalation

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5
Q

What is the average expiratory reserve volume?

A

1100ml

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6
Q

What is the inspiratory reserve volume defined as?

A

The maximum you can breathe in NOT lung capacity

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7
Q

What is the volume of the IRV

A

3000ml

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8
Q

What is the inspiratory capacity?

A

The inspiratory reserve + a normal inhaled breath

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9
Q

What is the value of the inspiratory capacity?

A

3500ml

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10
Q

What is the vital capacity?

A

The max volume of air you can shift in one breath

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11
Q

What two other volumes is the vital capacity defined by and what does it equal?

A

Inspiratory capacity + expiratory reserve volume = 4600ml

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12
Q

What is functional residual capacity?

A

Volume of air left in the lungs after a normal exhalation

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13
Q

What other two volumes is the functional residual capacity defined by and what does it equal?

A

Expiratory reserve volume + residual volume = 2300ml

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14
Q

What is the residual volume?

A

The volume of air that can’t be expelled from the lungs = 1200ml

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15
Q

What is the point of the residual volume (2 points)?

A
  • Keeps the alveoli partially inflated so that it is easier to breathe in on the next breath - Maintains a pressure gradient for gas exchange to continue between breaths
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16
Q

What is pulmonary ventilation and is it functionally significant?

A

The total air movement in and out of the lungs, no

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17
Q

What is alveolar ventilation?

A

The volume of fresh air reaching the alveoli and therefore available for gas exchange

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18
Q

What will alveolar ventilation indicate?

A

The amount of gas exchange occurring

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19
Q

If lung volume = 2200ml after a normal exhilation, how high will the volume be after a normal inhilation?

A

2700ml

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20
Q

How much of the 500ml breath will reach the alveoli?

A

350ml as 150ml will be in the dead space

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21
Q

Describe what is going on in the diagram

A
  • Respiratory cycle
  • Indicating that the not all of the 500ml inhaled air will reach the alveoli for gas exchange
  • 150ml MUST always be in the anatomical dead space
  • After expiration, the anatomical dead space is filled with stale air
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22
Q

When should you consider the implication of stale air in the anatomical dead spaces when dealing with patients?

A
  • Anxious patients will have a low tidal volume and a high RR which means their pulmonary ventilation will be normal but the alveolar ventilation will be low (hypoventilation)
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23
Q

What is hyperventilation?

A

When more air reaches the alveoli and alveolar ventilation is higher than normal, but pulmonary is the same

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24
Q

What is the partial pressure?

A

Pressure of a gas in a mixture of gases = % of gas in the mixture x the pressure of the whole gaseous mixture

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25
Q

EXAMPLE OF PARTIAL PRESSURE CALCULATION

A

Atmospheric Pressure = 760mmHg

Pressure of air we breathe therefore = 760mmHg

21% of air we breath = O2

Partial pressure of O2 in air we breath = 21% x 760mmHg

= 160mmHg

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26
Q

What do the pressures of O2 and CO2 do under normal conditions in the alveoli?

A

Remain constant

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27
Q

What is the normal PO2 in kPa and mmHg?

A
  • 13.3kpA
  • 100mmHg
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28
Q

How can PO2 and PCO2 vary?

A

With hyper and hypo ventilation

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29
Q

What happens to PO2 and PCO2 during hypoventilation?

A
  • PCO2 increases to 100mmHg
  • PO2 decreases to 30mmHg
30
Q

What happens to PO2 and PCO2 ​during hyperventilation?

A
  • PO2 increases to about 120mmHg
  • PCO2 decreases to about 20mmHg
31
Q

What cells produce surfactant?

A

Type 2 pneumocytes

32
Q

What is the main function of surfactant?

A
  • Reduces surface tension
33
Q

What is surface tension?

A

The attraction between air and water due to the attraction between water-water molecules, as shown below

34
Q

What does surface tension encourage the alveoli to do?

35
Q

What is the definition of compliance?

A

Change in volume related to change in pressure, i.e. how much the lungs will inflate with an increase of intrapleural pressure

36
Q

What is the effect of surfactant on compliance and lung recoil?

A
  • Increased compliance
  • Reduced lung recoil
37
Q

What effect does surfactant ultimately have on breathing

A

Makes it easier

38
Q

During embryonic development, at what stage does surfactant production begin?

39
Q

What can an inability to produce surfactant result in in newborns?

A

Infant Respiratory Distress Syndrome

40
Q

What is the law of laplace?

A

P = 2T/r

P - pressure

T - surface tension

r - radius

41
Q

If the alveolus was bigger, why would the pressure be lower?

A

Increase the value of r in P = 2T/r which would mean a lower pressure

42
Q

What is found in the lungs to counteract the small R?

A

Surfactant reduces the value of T so P is still low

43
Q

Why is surfactant more effective in small alveoli?

A

Found in higher concentrations due to less space

44
Q

What is high compliance?

A

Lung volume increases with a small intrapleural pressure increase

45
Q

When does a high compliance occur?

A
  • Healthy lungs
  • Emphysema
46
Q

Why is there a high compliance with emphysema?

A
  • Elastase is activated
  • Reduces elastin in the lungs
  • Lungs can’t expand as far as they should so less air is taken in when intrapleural pressure is reduced
47
Q

What is low compliance?

A
  • Low volume increase from a large pressure change in the lungs
48
Q

Where would you see low compliance?

A
  • Unhealthy lungs
  • Bronchitis
  • Restrictive disease
49
Q

What does compliance tell you about and what does it not give an indication of?

A
  • Tells you about how effectively the lungs fill up
  • Does not give any indication into elastic recoil
50
Q

Why does intrapleural have to become more negative during inspiration than expiration?

A
  • Has to overcome surface tension
  • Expiration has the aid of elastic recoil
51
Q

Why does inspiration follow an exponential curve?

A
  • Similar to spontaneous reactions in that in needs some more energy to start
  • Imagine blowing up a balloon and that it gets easier after you have it going
52
Q

Why is higher pressure needed to expire as you breathe out?

A

Need to overcome a higher resistance as airway muscle contracts to push air out

53
Q

Why is normal expiration passive?

A

Elastic recoil

54
Q

Why do people with emphysema have to expend more energy to breathe out?

A

Loss of elastic tissue means loss of elastic recoil

55
Q

Why does fibrosis reduce compliance?

A

More work needed to inflate the alveoli as they don’t stretch

56
Q

Which part of the lung has better compliance and which part has worse compliance?

A
  • Bottom of the lung is better
  • Apex is worse
57
Q

Why does the bottom of the lung have better compliance?

A

Due to gravity more air is forced out of the alveoli at the bottom of the lung, the apex retains a higher reserve volume so doesn’t intake as much air

58
Q

What is an obstructive respiratory disease attributed with?

A

Air flow obstruction particularly during expiration

59
Q

State 3 obstructive diseases

A
  • Asthma
  • Bronchitis
  • Emphysema
60
Q

How many people worldwide are affected by COPD?

A

80 million

61
Q

What type of disease is fibrosis?

A

Idiopathic

62
Q

Exposure to what can cause restrictive pulmonary disease?

63
Q

Give 2 examples of restrictive diseases

A
  • Fibrosis
  • Asbestosis
  • IRDS
  • Oedema
  • Pneumothorax
64
Q

What 5 things can spirometry measure?

A
  • Tidal volume
  • Expiratory Reserve
  • Inspiratory Reserve
  • Inspiratory Capacity
  • Vital Capacity
65
Q

What is static spirometry?

A

Measures volume of air exhaled

66
Q

What is dynamic spirometry?

A

Time taken to exhale a certain volume

67
Q

What does FEV1/FVC stand for?

A

Forced expiratory volume in 1 second/forced vital capacity

68
Q

What is FEV1/FVC usually equal to?

69
Q

What FEV1/FVC would an obstructive disease show?

A

A smaller percentage

70
Q

What FEV1/FVC would an restrictive disease show?

A
  • Both air flow rate and lung capacity is reduced
  • Percentage remains high

Respiratory Physiology (16 decks)

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