Ventilation and Compliance 2 Flashcards

1
Q

What are the 2 kinds of cells that makes up alveolar walls?

A

Type 1 (gas exhange)

Type 2 (secretes surfactant fluid)

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2
Q

What do type 1 cell of alveoli do?

A

Allows gas exchange

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3
Q

What do type 2 cells of alveoli do?

A

Secretes surfactant fluid

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4
Q

What is surfactant?

A

Detergent like fluid produced by type 2 alveolar cells

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5
Q

What does surfactant do?

A

Reduces surface tension on alveolar surface membranes, reducing tendancy for alveoli to collapse

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6
Q

What is surface tension?

A

Attraction between water molecules, occurs wherever there is an air-water interface

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7
Q

What does surfactant do to the compliance of the lung?

A

Increases it

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8
Q

What does surfactant do to the lungs tendency to recoil?

A

Reduces it

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9
Q

Is surfactant more effective in small or large alveoli, and why?

A

Small because surfactant molecules come closer together and are therefore more concentrated

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10
Q

Why does air spread evenly between small and large alveoli although there would be a pressure difference?

A

Surfactant reduces surface tension better in small alveoli, making the pressure in small and large equal

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11
Q

When does surfactant production begin and is completed by?

A

About 25 weeks gestation and is completed by 36 weeks

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12
Q

What is production of surfactant stimulated by?

A

Thyroid hormones which increase towards the end of pregnancy

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13
Q

What do premature babies often suffer from due to surfactant production being complete at week 36?

A

Infant respiratory distress syndrome

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14
Q

What is a saline filled lung similar to?

A

A lung in utero

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15
Q

Why does a lung in utero require a smaller change in pressure to inflate?

A

Does not need to overcome surface tension (no air-water interface)

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16
Q

What is compliance?

A

Change in volume relative to change in pressure

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17
Q

What does compliance of the lung represent?

A

Stretch ability of the lung (not elasticity)

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18
Q

What does a high compliance mean?

A

Large increase in lung volume for a small increase in ip pressure

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19
Q

What does a low compliance mean?

A

Small increase in lung volume for a large decrease in ip pressure

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20
Q

What does compliance change with?

A

Disease and age

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21
Q

Does it require a greater change in pressure from fictional residual capacity to reach a lung volume during inspiration or expiration?

A

Greater change in pressure is required during inspiration

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22
Q

Why is expiration passive?

A

Work on inspiration is recovered as elastic recoil during expiration

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23
Q

What is emphysema?

A

Loss of elastic tissue means expiration requires effort (image c)

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24
Q

What is loss of elastic tissue called?

A

Emphysema

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25
Q

What is fibrosis?

A

Inert fibrous tissue means effort of inspiration increases (image d)

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26
Q

What is inert fibrous tissue called?

A

Fibrosis

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27
Q

What does inert mean?

A

Lacking the ability or strength to move

28
Q

Does emphysema make inspiration or expiration more difficult?

A

Expiration (image c)

29
Q

Does fibrosis make inspiration or expiration more difficult?

A

Inspiration (image d)

30
Q

What does the pressure/volume curve vary between?

A

The apex and the base of the lung

31
Q

Is the volume change (compared to change in pressure) greater at the base or the apex of the lung?

A

Base

32
Q

How does alveolar ventilation and compliance change with height from the base to the apex and why?

A

Decreases due to alveolar at the apex being more inflated at functional residual capacity

33
Q

Why are the alveoli at the base more compliant during inspiration?

A

They are compressed between the lung above and the diaphragm below

34
Q

How does the change in intrapleural pressure affect the change in volume at the base of the lung compared to the apex?

A

Brings about a larger change at the base compared to the apex

35
Q

What are the 2 categories of lung disease?

A

Obstructive

Restrictive

36
Q

What does an obstructive lung disease mean?

A

Obstruction of airflow, especially on expiration

37
Q

What could an obstructive lung disease be due to?

A

Increased airway resistance

38
Q

What does a restrictive lung disease mean?

A

Restriction of lung expansion

39
Q

What could a restrictive lung disease be due to?

A

Loss of lung compliance, leading to lung stiffness and incomplete lung expansion

40
Q

What are examples of obstructive lung diseases?

A

Asthma

Chronic obstructive pulmonary disease (COPD)

41
Q

What are examples of chronic obstructive pulmonary diseases?

A

Chronic bronchitis

Emphysema

42
Q

What is chronic bronchitis?

A

Inflammation of the bronchi

43
Q

What is emphysema?

A

Destruction of alveoli, loss of elasticity

44
Q

What is destruction of the alveoli known as?

A

Emphysema

45
Q

How many people suffer from moderate to severe chronic obstructive pulmonary disease (COPD) worldwide?

A

80 million people

46
Q

What percent of the UK population suffers from chronic obstructive pulmonary disease (COPD) and how does this change with age?

A

About 1%, which increases with age

47
Q

What percent of men older than 75 suffer from chronic obstructive pulmonary disease (COPD)?

A

10%

48
Q

What are examples of restrictive lung diseases?

A

Fibrosis

Infant respiratory distress syndrome

Oedema

Pneomothorax

49
Q

What is infant respiratory distress syndrome?

A

Insufficient surfactant production

50
Q

What is spirometry?

A

Technique used to measure lung function

51
Q

What can the measurements from spirometry be classed as?

A

Static (where the only consideration made is the volume exhaled)

Dynamic (where the time taken to exhale a certain volume is what is being measured)

52
Q

What are static spirometry measurements?

A

Ones where the only consideration made is the volume exhaled

53
Q

What are dynamic spirometry measurements?

A

Ones where the time taken to exhale a certain volume is what is being measured

54
Q

What measurements can be made directly from spirometry?

A

Tidal volume

Inspiratory reserve volume

Expiratory reserve volume

Inspiratory capacity

Vital capacity

55
Q

What is FEV1?

A

Forced expiratory volume in 1 second

56
Q

What is FEV1 for a fit, healthy, young adult male?

A

4L

57
Q

What is FVC?

A

Forced vital capacity

58
Q

What is forced vital capacity for a fit, healthy young adult male?

A

5L

59
Q

What is the normal FEV1/FVC ratio for healthy young men?

A

80%

60
Q

How does the FEV1/FVC ratio change with obstructive and restrictive diseases?

A

Restrictive - FEV1 and FVC decrease, ratio decreases

Obstructive - FEV1 and FVC decrease, ratio increases

61
Q

Why is FEV1 reduced by a much greater extent than FVC for obstructive lung diseases?

A

Because major effect on airways

62
Q

Why is FVC decreased in restrictive lung diseases?

A

Due to limitations on lung expansion

63
Q

Why is the FEV1/FVC ratio not always a good indicator of health?

A

Because disease can cause it to decrease or increase, as seen with obstructive and restrictive lung disease

64
Q

What is forced expiratory flow (FEF25-75)?

A

Average expired flow over the middle of an FVC

65
Q

How do changes for forced expiratory flow compare to FEV1 with disease?

A

They correlate but changed for forced expiratory flow are more striking