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Body Systems > Respiratory Strand: Lecture 2 and 3 - Mechanisms of breathing > Flashcards

Respiratory Strand: Lecture 2 and 3 - Mechanisms of breathing Flashcards

1
Q

What is the definition of breathing?

A

The bodily function that leads to ventilation of the lungs. Also known as external respiration

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2
Q

What is the definition of ventilation?

A

The process of moving gases in (inspiration) and out (expiration) of the lungs

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3
Q

How can diseases affecting ventilation be classified? Give examples

A

-obstructive conditions e.g asthma, lung cancer -restrictive conditions: intrinsic e.g pulmonary fibrosis or extrinsic

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4
Q

What is an idiopathic disease?

A

when you don’t know what causes a disease, but something does

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5
Q

What do we depend on for the movement of air?

A

Pressure gradient between atmosphere and alveoli

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6
Q

What pressure differential causes inspiration?

A

Pb > Pa (Pb = barometric pressure/ atmospheric pressure)

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7
Q

What pressure differential causes expiration?

A

Pa>Pb

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8
Q

How do alveolar pressure changes occur? Give formula

A

They occur secondary to thoracic volume changes P α 1/V

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9
Q

Which inspiratory muscles do we use for quiet breathing?

A

Diaphragm External intercostals stabilise rib cage image

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10
Q

Which inspiratory muscles do we use for increasing effort whilst breathing?

A

Diaphragm External intercostals lift & expand rib cage Accessory muscles Neck muscles Shoulder girdle muscles

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11
Q

What do the external intercostal muscles do?

A

Move the ribcage upwards and outwards to increase the lateral and antero-posterior diameter of the thorax

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12
Q

How do expiratory muscles perform quiet breathing?

A

Elastic recoil of tissues

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13
Q

Which expiratory muscles do we use for increased effort breathing?

A

Internal intercostals Abdominal wall muscles

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14
Q

What nerves are in the diaphragm?

A

Phrenic nerves (C3, C4, C5)

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15
Q

What nerves are in the intercostals?

A

Segmental thoracic nerves

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16
Q

Why are the pleura important?

A

To transmit thoracic cage expansion into lung volume expansion Thoracic cage expansion exerts an increasing negative pressure on the intrapleural space

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17
Q

How does breathing in occur?

A
  1. intra pleural pressure goes down 2. air moves in 3. alveolar pressure goes down then back up to zero (equilibrates)
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18
Q

How does breathing out occur?

A
  1. Relax muscles 2. volume in chest goes down 3. alveolar pressure goes above zero 4. air moves out
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19
Q

How is the volume of air moving in and out of the lungs during ventilation measured?

A

a spirometer

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20
Q

What is tidal volume?

A

the volume of air moved in and out of the lungs during normal breathing

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21
Q

What is the inspiratory reserve volume?

A

After a normal expiration, take as deep a breath in as possible the maximal amount of additional air that can be drawn into the lungs by determined effort after normal inspiration

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22
Q

What is the expiratory reserve volume?

A

After a normal inspiration, breath out as deeply as possible the additional amount of air that can be expired from the lungs by determined effort after normal expiration

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23
Q

What is the residual volume?

A

Even after a maximal expiration, air remains in the lungs This is because of the rigid nature of the thorax and the pleural attachment of the lungs to the chest wall that prevent complete emptying of the lungs This is the residual volume

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24
Q

What are the 4 lung volumes?

A

-tidal volume -inspiratory reserve volume -expiratory reserve volume -residual volume

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25
Q

How do we calculate total lung capacity?

A

Total lung capacity = TV+ IRV + ERV + RV

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26
Q

How do we calculate vital capacity?

A

Vital capacity = TV + IRV + ERV

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27
Q

How do we calculate functional residual capacity?

A

functional residual capacity = ERV+ RV

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28
Q

What is vital capacity?

A

After a maximal inspiration, make a maximal expiration

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29
Q

What would a spirometry trace look like?

A
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30
Q

How do restrictive diseases affect e.g pulmonary fibrosis affect lung volumes and/or capacities?

A

reduced RV, FRC, VC, TLC

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31
Q

How do obstructive lung diseases e.g asthma, COPD, emphysema affect lung volumes and/or capacities?

A

-increased RV -TLC may change -FRC increased in emphysema

32
Q

What is compliance? what is the formula?

A

Compliance is defined as the change in lung volume per unit change in intrathoracic pressure Compliance = change in volume / change in pressure

33
Q

What is the functional residual capacity dependent on?

A

FRC is dependent on the compliance of the lungs and the chest wall

34
Q

How do we measure compliance?

A

We use a spirometer for volume and an oesophageal balloon for pressure

35
Q

What is atmospheric pressure equal to?

A

0 - and all other pressures are relative

36
Q

What is recoil pressure of the lung?

A

The difference between alveolar pressure and the pleural pressure Palv-Ppl = recoil pressure

37
Q

What is the glottis?

A

The throat

38
Q

What is the recoil pressure of the lung at maximal inspiration?

A

image slide 34

39
Q

What is the recoil pressure of the lung at end expiration/tidal breathing?

A

image slide 35

40
Q

What is the recoil pressure of the lung at peak inspiration

A

image slide 36

41
Q

What does a lung compliance curve look like?

A

image slide 37

42
Q

How do we calculate the recoil pressure of the chest wall?

A

Pw= Ppl - Pbs Pw = pressure in chest wall

43
Q

What is the recoil pressure of the chest wall at maximal expiration, closed glottis and relaxed muscles?

A

slide 39

44
Q

What is the recoil pressure of the chest wall when the glottis is open with the muscles relaxed?

A

slide 40

45
Q

What is the recoil pressure of the chest wall during maximal inspiration, closed glottis and relaxed muscles?

A

slide 41

46
Q

What is FRC?

A

The relaxation point of the respiratory system, when chest wall and lung recoil pressures are equal but opposite

47
Q

Give 3 diseases associate with reduced compliance?

A

-circumferential burn -pulmonary fibrosis -kyphoscoliosis - affects the compliance of the chest wll

48
Q

Give details about a disease associated with increased compliance

A

Emphysema: an obstructive condition destroys the elastic tissue of the lung itself

49
Q

Is the closing capacity usually larger or smaller than the FRC?

A

the closing capacity is usually less than the FRC

50
Q

What happens if the closing capacity exceeds the FRC?

A

Alveoli in dependent lung regions will be poorly ventilated - this causes you to have an inefficient respiratory system

51
Q

Are alveoli all the same size?

A

No they’re all different sizes

52
Q

What is the law of Laplace?

A

P = 2t/r where p = pressure t= surface tension r = radius of the bubble

53
Q

What is surface tension?

A

the force required to maintain a gas-liquid interface

54
Q

What is the structure of the alveoli?

A
55
Q

what do type II alveolar cells do?

A

-they have defence functions for fighting infections and secretes surfactant

56
Q

What is surfactant and what does it do?

A

-a soapy substance that lines the inner membrane on the alveoli -produced by type II alveolar cells -90% phospholipid, 10% protein -acts as a detergent to reduce alveolar surface tension -present in all alveoli -increases pulmonary compliance -prevents atelectasis (collapsed lung) -minimises alveolar fluid -deficient in infant respiratory distress syndrome

57
Q

How does surfactant equalise pressure between alveoli of different sizes?

A

surfactant becomes more dispersed as alveolar volume increases it reduces the surface tension more in smaller alveoli so it balances out the surface tension its present in the same quantity even if alveoli are different sizes

58
Q

What is the difference in the shape of the curve when we take static measurements of air in the lungs compared with when we measure during movement of gases?

A

image slide 55

59
Q

What is hysteresis?

A

the phenomenon in which the value of a physical property lags behind changes in the effect causing it

60
Q

What are the two causes of hysteresis?

A

At small lung volumes: 1. Reduced compliance of elastic structures 2. Airway calibre (calibre= diameter of bronchioles)

61
Q

How does airway calibre have a large effect on flow? use formula

A

Flow = k.ΔP. r4 / L where: -k is a constant -ΔP - pressure differential between the top and bottom of cylinder

62
Q

By how much will the flow be reduced if the radius is reduced by half?

A

flow will reduce by 16 fold

63
Q

What is laminar flow?

A

When all air molecules are going in a nice organised path, not bumping into each other

64
Q

How many divisions of the trachea are there?

A

23-from the trachea to the alveolar sacs trachea, bronchi, bronchioles, terminal bronchioles, respiratory bronchioles, alveolar ducts, alveolar sacs

65
Q

What is a vitalograph spirometer used to measure?

A

-the forced vital capacity (FVC) -the forced expiratory volume in 1 second (FEV1)

66
Q

What is a peak flow used to measure?

A

the peak expiratory flow rate (PEFR) - convenient way of measuring airway obstruction (not as good as spirometry)

67
Q

What are the differences in PVC and fev1 in patients with normal, obstructive and restrictive pulmonary disease

A
68
Q

What can distinguish between obstructive and restrictive lung conditions?

A

FEV1 / FVC ratio

69
Q

What is a key difference between asthma and COPD?

A

Asthma - the airway constriction is reversible so that the FEV1 and PEFR would be restored to normal after salbutamol COPD - airway constriction is irreversible

70
Q

How is energy used in inspiration?

A

To overcome elastic forces - stored as potential energy which is dissipated in expiration

71
Q

How do we calculate work?

A

work = volume x pressure

72
Q

What are 7 other functions of the lung other than gas exchange?

A
  1. Expulsion of air from the lungs to produce sound and speech (phonation)
  2. Conversion of angiotensin I to angiotensin II in the regulation of blood pressure and volume
  3. Local production of surfactant (a phospholipid) to decrease surface tension in the alveolar cells
  4. Act as a reservoir of blood
  5. Filtration of small blood clots from the blood to prevent them entering the systemic circulation
  6. Secretion of immunoglobulin (mainly IgA) into bronchial mucus in response to allergic challenges
  7. Maintenance of acid-base balance - by excretion of carbon dioxide
73
Q

Is Bronchiectasis reversible or irreversible?

A

A disease with irreversibe dilation of the bronchial walls

74
Q

What does pulmonary fibrosis result from?

A

Pulmonary fibrosis results from lung scarring and cyst formation arising from inflammation of the airways.

75
Q

What is the change in inflating pressure and how is it measured?

A

the difference between atmospheric pressure and intrapleural pressure, measured by an oesophageal balloon

Body Systems (24 decks)

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