Brainscape's Knowledge GenomeTM

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


See full index

Respiratory system > Surfactant, compliance and lung function tests > Flashcards

Surfactant, compliance and lung function tests Flashcards

1
Q

what is the function of surfactant?

A

it decreases the suface tension on the alveolar membrane thus reducing the tendency for alveoli to collapse

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

where does surface tension occur and what is it?

A

the boundary between air and water. It is the attraction between water molecules

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

what is the direction of the force caused by surface tension of water molecules arranged in a circle/sphere?

A

inwards

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

how does surfactant prevent the collapse of alveoli?

A

the surfactant molecules lie between water molecules around the inside of the alveoli, this reduces surface tension

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

what are the functions of surfactant?

A
  • reduces surface tension to prevent alveoli collapsing.
  • increases lung compliance
  • reduces lung’s tendency to recoil
  • makes work of breathing easier
  • is more efficient in small alveoli so prevents air moving from small alveoli to larger ones.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

explain the problem with alveoli of different sizes and how surfactant solves this

A

with out surfactant the inward pressure in smaller alveoli would be much higher than in larger alveoli, and so air would move from small to large alveoli. This is unfavourable as the surface area to volume ratio would decrease. sufactant combats this as it’s more concentrated in the smaller alveoli and rerduces the pressure in them more, equalising the pressure in all alveoli.

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

what is infant respiratory distress syndrome?

A

a condition that effects babies born very prematurely . they have not yet started to produce adequate amounts of surfactant so an immense amount of effort is required for them to breath to overcome the surface tension in their alveoli.

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

what is the difference between the effort required to inflate and deflate a lung in saline solution compared with air and why is this important for infant respiratory distress syndrome?

A

it requires a much greater increase in pressure to inflate a lung in air than in saline solution and a much greater decrease for deflation.
This means that when a baby is born it must use much more effort to breath even with surfactant, without surfactant it would be significantly more again.

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

what is compliance?

A

change in volume relative to change in pressure

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

what does compliance represent?

A

it represents stretchability (not elasticity)

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

what does a high compliance mean?

A

large increase in lung volume for small decrease in ip pressure

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

what does a low compliance mean?

A

small increase in lung volume for large decrease in ip pressure

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

describe how compliance will be altered with patients with emphysema

A

it will be normal as emphysema does not affect lung stretch, just recoil.

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

what is emphysema?

A

a break down of the elastic fibres around alveoli, it affects recoil of the lungs

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

what is fibrosis in the lungs?

A

the build up of fibrous tissue in the lungs around the alveoli

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

how does fibrosis affect compliance?

A

it causes it to decrease as it decreases stretch

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

how does compliance change with age?

A

it decreases

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

does it require a greater pressure change to maintain a volume during expiration or reach the same volume by inspiration? why?

A

reach the volume by inspiration. this is because the tissue inertia has to be overcome and so does the surface tension as surfactant conc. is low

19
Q

what does a less steep line on a volume-pressure graph indicate about compliance?

A

lower compliance

20
Q

what happens to alviolar ventilation moving from base to apex?

A

it decreases

21
Q

what happens to compliance moving from base to apex of lung?

A

it decreases

22
Q

why does compliance decreases moving from base to apex?

A

the alveoli at the base of the lungs are more compressed due to the weight of the lung above them, the alveoli at the apex are more inflated so a change in pressure causes less change in volume.

23
Q

a change is intrapleural pressure will bring about the biggest change in which area of the lung?

A

the base

24
Q

what is an obstructive lung disease?

A

the airways are obstructed, especially on expiration

25
Q

what is a restrictive lung disorder?

A

the expansion of the lung during inspiration is restricted

26
Q

what does an obstructive lung disorder do to the airways?

A

increases their resistance

27
Q

give some examples of obstructive airway disorders?

A

Asthma

COPD eg. chronic bronchitis, emphysema

28
Q

what is chronic bronchitis?

A

inflammation of the bronchi

29
Q

what is emphysema?

A

destruction of elastic fibres and destruction of alveoli

30
Q

what does a restrictive lung disorder do to the lungs?

A

causes loss of lung compliance: lung stiffness, incomplete lung expansion

31
Q

what is fibrosis?

A

formation or development of excess fibrous connective tissue

32
Q

what causes fibrosis?

A

asbestosis

idiopathic

33
Q

which conditions are classified as restrictive airway disorders?

A
  • fibrosis
  • infant respiratory distress syndrome
  • oedema
  • pneumothorax
34
Q

what is spirometry?

A

technique commonly used to measure lung function

35
Q

what is a static spirometry reading?

A

where the only comsideration made is the volume exhaled

36
Q

what is a dynamic spirometry reading?

A

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

37
Q

which volumes is the spirometer able to measure?

A
  • tidal volume
  • inspiritory reserve level
  • expiratory reserve volume
  • inspiratory capacity
  • vital capacity
38
Q

what is the FEV1/FVC in a normal person?

A

80%

39
Q

how does FEV1/FVC differ from normal in a suffer of an obstructive airway disorder? why?

A

it is lower (than 80%).
rate of exhalation is much slower, so is total volume but major effect is on airways and so FEV is reduced to a greater extent than FVC

40
Q

how does FEV1/FVC differ from normal in a suffer of a restrictive airway disorder? why?

A

it is the same or higher (than 80%).
Absolute rate of airflow is reduced
Total volume is reduced due to limitations to lung expansion
Ratio remains constant or can increase as a large proportion of volume can be exhaled in the first second

41
Q

what is a limitation of spirometry?

A

the ratio obtained is not always enoug to indicate health particulary for restrictive pulmonary disorders. Absolute values are required to show ill-health

42
Q

what is forced expiratory flow?

A

average expired flow over the middle of an FVC. 25% through FVC divided by 75% throuh FVC

43
Q

what are the advantages and disadvantages of forced expiratory flow?

A
  • Correlates with FEV1 but changes are generally more striking
  • However “normal” range is greater

Respiratory system (38 decks)

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