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Medicine - Foundation > Mechanics Of Respiration > Flashcards

Mechanics Of Respiration Flashcards

(60 cards)

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1
Q

Inspiratory muscles

A
  • Sternocliedomastoid
  • Scalenes
  • External intercostals
  • Diaphragm
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2
Q

Process of inspiration

A
  • Ribs elevated
  • Sternum flares
  • Diaphragm moves downwards
  • External intercostals contract
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3
Q

Accessory muscles of inspiration function

A

Involvement in forced inspiration

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4
Q

Accessory muscles of inspiration examples

A
  • Scalene
  • Major/minor pectoralis
  • Sternocleidomastoid
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5
Q

Scalene during inspiration

A

Contraction enlarges the upper ribcage

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6
Q

Major/minor pectoralis during inspiration

A

Draws rib cage superiorly

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7
Q

Sternocleidomastoid durig inspiration

A

Elevates sternum

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8
Q

Process of expiration

A
  • Ribs and sternum depressed
  • Diaphragm relaxes and moves upwards
  • Recoil of lung
  • External intercostals relax
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9
Q

Accessory muscles of expiration function

A

• Active only in deep expiration

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10
Q

Accessory muscles of expiration examples

A
  • Internal intercostals
  • External abdominal oblique
  • Internal abdominal oblique
  • Transverse abdominis
  • Rectus abdominis
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11
Q

Internal intercostal muscles during expiration

A

Contract to depress the rib downwards

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12
Q

Abdominal muscles during expiration

A

Contract to force abdominal content up against relaxed diaphragm

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13
Q

Pulmonary pressures types

A
  • Intra-alveolar (intrapulmonary) pressure
  • Intrapleural pressure
  • Transpulmonic (transpleural) pressure
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14
Q

Transpulmonic pressure

A

P(alv) - P(ip)

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15
Q

Intra-alveolar pressure value at rest

A

P(av) = P(atm) = 760 mm Hg

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16
Q

Intra-alveolar pressure during normal inspiration

A

Slightly negative wrt atmospheric pressure -> air flows into lung

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17
Q

Intra-alveolar pressure during forced inspiration

A

Becomes more negative

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18
Q

Intra-alveolar pressure during passive expiration

A

Greater than atmospheric pressure

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19
Q

Intra alveolar pressure during forced expiration

A

Value increases (more positive)

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20
Q

Intrapleural pressure at rest

A

Subatmospheric (756 mmHg)

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21
Q

Intrapleural pressure during normal inspiration

A

-7 mmHg

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22
Q

Intrapleural pressure during normal expiration

A

-4 mmHg

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23
Q

Intrapleural pressure during forced inspiration

A

More negative

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24
Q

Intrapleural pressure during forced expiration

A

Becomes less negative, may exceed atmospheric pressure

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25
Transpulmonic (transpleural) pressure definition
Pressure gradient across wall of lung P(av) - P (ip) Pressure that keeps lung from collapsing
26
Transpulmonic pressure at rest
760 - 756 = 4 mmHg
27
Transpulmonic pressure magnitude
* ALWAYS positive | * More positive during inspiration
28
Zero transpulmonic pressure
* Lung collapses (atelectasis) | * Occurs when air enters intrapleural space (pneumothorax)
29
Sequence of events during inspiration
1. Diaphragm and external intercostals contract 2. Thorax expands 3. P(ip) becomes more subatmospheric 4. Increase in transpulmonic pressure 5. Lungs inflate 6. P(av) becomes subatmospheric 7. Air flows into alveoli
30
Sequence of events during expiration
1. Diaphragm & ext intercostals relax 2. Chest wall moves inwards 3. P(ip) back towards preinspiration value 4. Decrease in transpulmonic pressure 5. Lungs recoil 6. P(av) becomes greater than P(atm) 7. Air flows out of alveoli
31
Nature of inspiration
Active process
32
Types of forces
* Lung elasticity * Alveolar surface tension * Airway resistance
33
Lung elasticity definition
Ability of the lung to stretch/recoil
34
Lung elasticity measurement
Measured by lung conpliance
35
Lung compliance definition
Change in lung volume per unit change in distending pressure
36
Lung compliance formula
C = Change in V/Change in P
37
Higher compliance implication
Easier for lung to expand
38
Lower lung compliance implication
More energy needed to breathe
39
Lung compliance factors
* Elasticity of lung and thoracic cage | * Surface tension in alveoli
40
Alveolar surface tension
Force that reduces alveoli to smallest size, pulling lungs inwards
41
Inflation of alveolus relationship
Distending pressure, tension and radius in walls of alveolus
42
Law of Laplace
P = 2T/r
43
Surfactant
Lipoprotein mixture secreted by type II alveolar cells into the alveoli
44
Functions of surfactant
* Decrease surface tension * prevent collapse of alveoli * Make lungs more distensible
45
Greatest airway resistance location
Medium-sized bronchi
46
Inspiratory reserve volume definition
Maximum amount inspired in excess volume of tidal volume
47
Inspiratory reserve volume value
3100ml
48
Tidal volume definition
Amount of air inspired or expired with each breath
49
Tidal volume value
500ml
50
Expiratory reserve volume definition
Maximum amount expired in excess volume of tidal volume
51
Expiratory reserve volume value
1200ml
52
Residual volume
Amount of air remaining in lungs after a maximum respiratory effort
53
Residual volume value
1200ml
54
Lung capacities types
* Vital capacity * Functional residual capacity * Total lung capacity
55
Vital capacity definition
Total amount of exchangeable air
56
Vital capacity formula
IRV + TV + ERV = 3.2 + 0.5 + 1.2 = 4.8L
57
Functional residual capacity definition
Amount of air left in lungs after tidal expiration
58
Functional residual capacity definition
ERV + RV = 1.2 + 1.2 = 2.4L
59
Total lung capacity definition
Maximum volume to which the lungs can be expanded with the greatest possible effort
60
Total lung capacity formula
IRV + TV + ERV + RV = 3.1 + 0.5 + 1.2 + 1.2

Medicine - Foundation (10 decks)

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