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BIOM20002 - HSF > Lecture 58 - Lung Volumes & Mechanics > Flashcards

Lecture 58 - Lung Volumes & Mechanics Flashcards

1
Q

Compare the angels of the left and right main bronchi

A

Right main bronchus: more vertical

Left main bronchus: more horizontal

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2
Q

Where is the largest surface area in the lung located?

A

Most of the surface are is at the alveoli (ie where exchange is occurring)

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3
Q

Describe the structure of the trachea

A

Cartilage rings

Trachelis muscle

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4
Q

What keeps the lungs inflated?

A

Pleural sac attaching to thoracic cavity

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5
Q

Describe the structure of the pleura

A

Parietal

Visceral

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6
Q

What is the pressure in the lungs?

A

1 atm

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7
Q

What is the pressure in the pleural cavity?

A

Less than 1 atm

Keeps the lungs stuck to the pleura

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8
Q

What happens when the intercostal muscles contract?

A

The ribs pull together and increase the volume inside

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9
Q

What happens when there is a puncture through the ribs?

A

Lung collapses down because the seal has been broken

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10
Q

What is Boyle’s law?

A

P1V1 = P2V2

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11
Q

What happens when volume in a cavity decreases?

A

Pressure increases

and vice versa

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12
Q

What happens to make inhalation happen?

A

Chest wall gets bigger
Pressure decreases in the thoracic cavity
Negative pressure → air flows into the lungs

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13
Q

What happens to make expiration happen?

A

Chest wall gets smaller
Pressure increases in the thoracic cavity
Positive pressure → air expelled

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14
Q

When pressure is higher in the lung than the atmosphere, where does air move?

A

Out of the lung

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15
Q

Describe the volume of air moved during the respiratory cycle

A

**

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16
Q

Describe which muscles are responsible for inspiration

A

Diaphragm
External intercostals
Scalenes
Mastoids

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17
Q

Which muscles are responsible for expiration

A

Normally passive

Internal intercostals for forced expiration

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18
Q

Describe Poiseuille’s law

A

Resistance proportional to length an viscocity

and inversely proportional to radius of the tube

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19
Q

What parameters of poiseuille’s law are varibale?

A

Radius of the bronchi

Viscosity and length of bronchi not variable

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20
Q

How is the diameter of the airways altered?

A

Upper airways: physical obstruction
• mucous

Lower airways
• ANS
• CO2
• epinephrine
• histamine
• leukotrienes
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21
Q

What happens as diameter of the airways deccreases?

A

Resistance increases

More work required

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22
Q

What is lung compliance?

A

The ability of the lung to stretch

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23
Q

What happens as compliance of the lung increases?

A

More work required to inflate the lungs

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24
Q

What factors affect lung compliance?

A

Surface tension in alveoli

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25
Q

What is surface tension due to?

A

Attraction of hydrogen molecules

They are trying to pull in close

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26
Q

What is the Law of LaPlace?

A

Pressure in smaller bubbles is greater (if surface tension is the same)

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27
Q

What does small alveoli mean?

A

Higher resistance to stretch

Greater inward pressure causing collapse

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28
Q

What prevents the alveoli from collapsing?

A
  1. Surfactant

2. Alveolar interdependence

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29
Q

What does Surfactant stand for?

A

Surface Active Agents

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30
Q

What does surfacant do?

A

Reduces surface tension
(Radius is the same)
→ pressure is reduce
H+ are happy to be further apart

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31
Q

Where is surfactant more concentrated?

A

In small alveoli

32
Q

According to Law of LaPlace, what is pressure proportional to?

A

Proportional to surface tension

Inversely proportional to radius

33
Q

Describe alveolar interdependence

A
  1. An alveolus collapses
  2. Surrounding alveoli stretched
  3. Recoil of stretched surrounded alveoli
  4. Collapses alveolus pulled back open
34
Q

What is the measurement of lung volumes?

A

Spirometry

35
Q

Describe spirometry

A

Breathes in: bucket goes down
Breathes out: bucket goes down

This is recorded by a machine

We can measure the volume going in and out

36
Q

What is capacity?

A

More than one lung volume

37
Q

What is tidal volume?

A

Volume of one breath in

500 mL

38
Q

What is the name for the total volume that we can expire if needed?

A

Expiratory reserve volume

1100 mL

39
Q

What is the name for the total volume that we can inspire if needed?

A

Inspiratory capacity

3500 mL

40
Q

What is the maximum volume we can expire

A

Vital capacity

4600 mL

41
Q

What is the volume in the lung that we can’t expel?

A

Residual volume

1200 mL

42
Q

What does the Helium dilution method tell us?

A

Allows estimation of:
• residual volume
• functional residual volume

43
Q

When is most of the air expired?

A

In the first second

44
Q

What is FEV1?

A

Volume of air expired in the first second

• 4 L

45
Q

What is FVC?

A

Forced vital capacity

5L

46
Q

What sort of diseases can occur in the lungs?

A
  1. Obstructive lung disease
    • narrowed lungs
    • can’t expire
2. Restrictive lung disease
• decrease in lung compliance due to scar tissue
• can't inhale
Pulmonary fibrosis
(asbestos, smoking)
47
Q

What things change in obstructive lung disease?

A 
Decrease in FEV
Decrease in FVC
Decrease in the ratio
Decrease in vital capacity
Increase in residual volume
48
Q

Why do people with Obstructive lung disease swim well?

A

More volume in the lungs

Increased residual volume

49
Q

What changes occur in restrictive lung disease?

A 
Decrease in FEV
Decrease in FVC
Ratio goes up
Decrease in vital capacity
No change in residual volume
Decrease total lung capacity
50
Q

What is dead space?

  • give examples of anatomical dead space
A

Part of the lungs that aren’t involved in gas exchange

Anatomical dead space
• trachea
• bronchi

51
Q

Describe the effect of anatomical dead space

A

Air trapped in the trachea that is not refreshed
This is taken back in during the next inspiration

This stale air has reduced partial pressure of oxygen

52
Q

What is the average tidal volume?

A

500mL

53
Q

What is the average breathing rate

A

12 breaths / min

54
Q

What is minute ventilation

A

Total ventilation over a fixed time period (usually a minute)

55
Q

What is alveolar ventilation?

A

Volume of alveolar air exchanged per unit time

Tidal vol - dead space

56
Q

What happens if we breathe TV of 150 mL at f = 40?

A

Minute ventilation doesn’t change

Alveolar ventilation does!

Pass out eventually, because of the dead space in the trachea

57
Q

What is normal total pulmonary ventilation?

A

6 L/min

58
Q

What is eupnea?

A

Normal quiet breathing

59
Q

Describe the structure of the bronchioles.

Compare this with the bronchi

A

Bronchi: cartilage rings to keep them open

Bronchioles: no cartilage
• smooth muscle innervated by ANS

60
Q

Describe what factors affect the resistance in the lungs

A

Resistance is proportional to:
• length of airway
• viscosity of air

Inversely proportional to:
• diameter

61
Q

What is work of breathing?

What affects it?

A

Work of breathing is how much energy is required, ie how much resistance that needs to be overcome

Resistance affects it.
• airway diameter
• lung compliance

62
Q

What is the difference between lung compliance and elastance?

A

Compliance: ability to stretch

Elastance: ability to spring back after stretching

63
Q

What things can affect lung compliance?

A

Pulmonary fibrosis
• causes decrease in compliance
• scar tissue is stiff

64
Q

What things can affect lung elastance?

A

Emphysema
• decreases elastance
• destroys elastin fibres

65
Q

What is the effect of histamines and leukotrienes on the bronchioles?

A

Bronchoconstriction

66
Q

What is the effect of epinephrine on the bronchioles?

A

Bronchodilation

67
Q

What causes restrictive lung disease?

How about obstructive lung disease?

A

Restrictive: decrease in compliance
• asthma
• emphysema

Obstructive: narrowing of lower airways
• pulmonary fibrosis

68
Q

What is normal Va?

A

4.2 L/min

69
Q

What is the name for increased respiratory rate?

A

Hyperpnea
• due to increased metabolism

Hyperventilation
• no increase in metabolism

70
Q

What is the apnea?

A

Cessation of breathing

71
Q

What is dyspnea?

A

Difficulty breathing

72
Q

What is tachypnea?

A

Rapid breathing

eg. panting

73
Q

What parameters in alveoli would change if it weren’t for surfactant?

A

Surface tension

Diameter of alveoli doesn’t change

74
Q

What would increased pressure in the alveoli result in?

A
  • Decreased compliance

* Increased work of breathing

75
Q

What is the important ratio?

A

• normally 80

FEV1 / FVC

BIOM20002 - HSF (60 decks)

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