Brainscape's Knowledge GenomeTM

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


See full index

Yr 2 - Respiratory System > Mechanics of Breathing > Flashcards

Mechanics of Breathing Flashcards

1
Q

What is the definition of breathing?

A

The bodily function that leads to ventilation of the lungs (external respiration)

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

Define ventilation

A

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

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

Define the mechanics of breathing

A

Describes the structural and physiological bases of ventilation

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

What 2 types of diseases affect lung volumes/capacities?

A
  1. Restrictive lung diseases - pulmonary fibrosis (intrinsic) and pneumothorax (extrinsic)
  2. Obstructive lung diseases - asthma, COPD, emphysema
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What does the movement of gas in and out of the lungs depend on?

A

Pressure differentials between atmosphere and alveoli for movement of gas.

Atmospheric pressure remains constant so flow is determined by changes in pressure within the lungs.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What change in pressure occurs for inspiration to happen?

A

Muscles of inspiration tense and volume of chest increases as lungs expand. Alveoli pressure falls bellow atmospheric pressure and air is drawn in

Pa < Pb

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

What change in pressure occurs for expiration to happen?

A

Muscles of inspiration relax and volume of chest and lungs decreases. Alveoli pressure exceeds atmospheric pressure and air is blown out

Pa > Pb

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

What do changes in alveolar pressure occur secondary to?

A

Changes in thoracic volume

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

What is atmospheric pressure sometimes referred to as?

A

Barometric pressure (Pb)

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

What inspiratory muscles are involved in quiet breathing?

A
  • Most work done by diaphragm (moves down)

- External intercostal muscles stabilise rib cage

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

What inspiratory muscles are involved in breathing with increased effort?

A
  • Diaphragm
  • External intercostal muscles lift and expand rib cage
  • Accessory muscles used (neck muscles and shoulder girdle muscles)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What does movement of external intercostal muscles result in?

A

Move ribcage up and out to increase the lateral and antero-posterior diameter of the thorax

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

Where does force that causes change in volume of chest and lungs come from?

A
  1. Contraction

2. Elastic properties of lungs and chest (similar to balloon)

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

What is tendency of lung?

A

To collapse unless held inflated by pressure difference between inside and outside

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

What 2 forces does the pleural pressure reflect?

A
  1. The force required to keep lung inflated against its elastic recoil
  2. The force required to cause airflow in and out of lung
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What is result of fixing the shoulder girdle? When is this seen?

A

Pectoralis major and latissimus dorsi muscles will pull ribcage outwards

Seen in patients with respiratory distress or athletes at end of hard race

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

How are abdominal muscles involved in forced expiration?

A

Pulls ribcage downwards and medially in forced expiration

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

How are expiratory muscles involved in quiet breathing?

A
  • Little voluntary effort required due to elastic recoil of tissues
  • Muscles of inspiration relax
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

How are expiratory muscles involved in increased effort breathing?

A
  • Active contraction of internal intercostals

- Abdominal wall muscles help to push diaphragm back up

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What are intercostals innervated by?

A

The intercostal nerves which arise from the anterior rami of the thoracic spinal nerves from T1 to T11 (respective nerve from thoracic spinal cord)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What is diaphragm innervated by?

A

Phrenic nerves (C3, C4, C5)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

In embryos, where is the origin of the diaphragm? How does this affect its innervation?

A
  • Origin in the neck that starts off as membrane that becomes muscle
  • Has nerves coming from cervical cord (phrenic nerves)
  • Supply from 3rd, 4th and 5th cervical segments
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

How are pleura involved in lung expansion?

A

Transmit thoracic cage expansion into lung volume expansion

Pressure in pleura always precedes the pressure change in alveolus

Thoracic cage expansion exerts an increasing negative pressure on intrapleural space (less than atmospheric so air drawn in)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

Why are some neck injuries survivable?

A

If damage to cervical cord is below the origins of the phrenic nerves (3rd, 4th and 5th) then diaphragm not paralysed

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

What is change in pressure in pleura affected by?

A

Movement of chest

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

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

A

Spirometer

  • Breathes in and pen moves up
  • Breathes out and pen moves down
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

How is pressure measured?

A

cm of H20

Negative –> less than atmospheric
Positive –> more than atmospheric

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

At the end of inspiration/expiration, what has happened pressure wise?

A

System in equilibrium –> equal pressure between alveoli and atmosphere and no movement of gas

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

Describe pressure changes during inhalation

A
  1. Patient breathes in
  2. Chest expands and volume increases
  3. Intrapleural pressure decrease
  4. Alveolar pressure decreases and becomes negative
  5. Generates pressure gradient so air sucked in
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

Describe pressure changes during exhalation

A
  1. Patient breathes out
  2. Volume in chest decreases
  3. Intrapleural pressure increases
  4. Alveolar pressure increases and becomes positive
  5. Air blown out
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

What is pneumothorax?

A

Air in the cavity between the lungs and chest wall (between layers of the pleura)
Causes collapse of lung

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

What is pleural effusion?

A

Fluid builds up in space between layers of pleura

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
33
Q

What are the 4 lung volumes?

A
  1. Tidal volume
  2. Inspiratory reserve volume
  3. Expiratory reserve volume
  4. Residual volume
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
34
Q

What is tidal volume? What are typical values at rest/during exercise?

A

The volume of air moved in or out of the lungs during normal breathing

o At rest 6-7 ml/Kg
o During exercise 15 ml/Kg

A typical value for tidal volume of an adult male is 500 ml

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
35
Q

What is the inspiratory reserve volume?

A

After normal expiration, take as deep a breath in as possible

Typical value for a 70kg male is 3000ml

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
36
Q

What is the expiratory reserve volume?

A

After a normal inspiration, breathe out as deeply as possible

Typical value for a 70kg male is 1500ml

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
37
Q

What is the residual volume?

A

Air that remains in lungs after maximal expiration

About 1.0 L

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
38
Q

Why does air remain in lungs after maximal expiration?

A

Because of the rigid nature of the thorax and the pleural attachments of the lungs to the chest wall that prevent complete emptying of the lungs

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
39
Q

How is residual volume measured?

A
  • Can’t be measured using spirometry
  • Measurement of RV based on the fact air contains around 80% nitrogen neither absorbed nor produced in the body
  • By washing all the N2 out of the lungs and measuring its volume, the volume of air that was in the lungs can be estimated.
  • To wash the N2 from the lungs, the subject breathes O2 (N2-free) gas and breathes out through a turbine volume-flow meter for a few minutes.
  • Normally 2 minutes are required in healthy adults but longer (7 minutes) may be necessary for people with asthma or emphysema.
  • The expired gas is collected and its N2 concentration measured and its volume determined.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
40
Q

What is the functional residual capacity?

A

Volume of air left in the lungs at end of normal expiration

  • The opposing elastic recoil forces of lungs and chest wall are in equilibrium
  • No exertion by diaphragm etc
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
41
Q

What is the recoil pressure of the lung?

A

Pressure of alveoli - Pressure of pleura

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
42
Q

What is the recoil pressure of the chest wall?

A

Pressure of pleura - Pressure of atmosphere

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
43
Q

Define compliance

A

The change in lung volume per unit exchange in intrathoracic pressure (i.e. measure of lung’s ability to stretch and expand_

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
44
Q

What is FRC dependent on?

A

Compliance of lungs and chest wall

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
45
Q

Describe lung with low compliance

A

Stiff lung with high elastic recoil (seen in fibrosis). Lots of energy required to increase volume.

46
Q

Describe lung with high compliance

A

Pliable lung with low elastic recoil (seen in emphysema). Elastic tissue damaged by enzymes (produced by leukocytes in response to inhaled irritant). Little energy required to increase volume

47
Q

What is volume in lung after maximal expiration? What is recoil pressure of lung?

A

Residual volume

Intrapleural pressure is as positive as it gets (-3) and alveolar pressure is 0

Recoil pressure –> 0 - -3 = +3 cm H20

48
Q

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

A

Relaxed breathing and intrapleural pressure is around -5

Recoil pressure –> 0 - -5 = +5 cm H20

49
Q

What is the volume in lung at end of normal tidal breathing?

A

Functional Residual Capacity

50
Q

Wha is recoil pressure of lung during peak inspiration?

A

Big breath in and hold it

Generates very negative pressure in intrapleural space (-30) so air drawn in

Recoil pressure –> 0 - -30 = +30 cm H20

51
Q

What does alveolar pressure remain at?

A

0 so recoil dependent on pleural pressure

52
Q

What is volume of chest wall after maximal expiration?

A

Residual volume

53
Q

What is recoil pressure of chest at maximal expiration?

A

Close glottis and relax muscles

Intrapleural pressure is negative (-30) during exhalation

Recoil pressure of chest wall –> -30 - 0 = -30 cm H20

54
Q

What is atmospheric pressure?

A

Always 0

55
Q

What is volume of chest after expiration normal breathing?

A

Functional residual capacity

56
Q

What is recoil pressure of chest after expiration normal breathing?

A

Open glottis with muscles still relaxed

Intrapleural pressure becomes less negative (-5)

Recoil pressire –> -5 - 0 = -5 cm H20

57
Q

What is recoil pressure of chest at maximal inspiration?

A

Close glottis and relax muscles

Intrapleural pressure becomes +3

Recoil pressure –> +3 - 0 = +3 cm H20

58
Q

What is FRC in terms of recoil pressures?

A

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

59
Q

What is scoliosis and how does it affect lungs?

A

Abnormal lateral curvature of spine which causes abnormal alignment of ribcage

60
Q

How can severe burns affect lungs?

A

Scar formation causes tightening of chest

61
Q

How do basal alveoli compare to upper alveoli?

A

Spaces at top are bigger than spaces at bottom so have different compliance

When you apply an equal pressure change, there is a bigger change in basal alveoli

Basal alveoli are better ventilated

62
Q

What is the closing capacity?

A

The volume in the lungs at which its smallest airways, the respiratory bronchioles, collapse. The alveoli lack supporting cartilage so depend on other factors to keep them open

63
Q

How is relationship between closing capacity and FRC?

A

Closing capacity is normally less than the FRC (amount of gas that normally remains in lungs) so there is normally enough air within lungs to keep these airways open during inspiration and expiration

64
Q

What happens to closing capacity as you age?

A

Gradual increase in closing capacity so small airways begin to collapse at higher volumes/before expiration is complete

65
Q

What are type 1 alveolar cells responsible for?

A

Gas exchange

66
Q

What are type 2 alveolar cells responsible for?

A

Secrete surfactant

67
Q

What is function of surfactant?

A

Acts as detergent to reduce alveolar surface tension

  • Increases pulmonary compliance
  • Minimises alveolar fluid
68
Q

What is deficient in infant respiratory distress syndrome?

A

Type 2 alveoli cells not producing surfactant

69
Q

What happens to surfactant as alveolar volume increases?

A

Surfactant becomes more dispersed and molecules less tightly packed

70
Q

What is the difference in compliance in the lungs due to?

A

Additional energy required to overcome surface tension forces during inspiration and to recruit and inflate additional alveoli

71
Q

What happens to resistance as lungs expand?

A 
The calibre (diameter) of the bronchioles expands so there is less resistance to flow 
- Decreasing radius of bronchus by half reduces flow by 16 fold
72
Q

What is laminar flow? Where does it occur?

A

Air flowing through tube in parallel layers with no disruption.

Occurs more in distal (lower) branches of alveolar tree (in smaller bronchi the overall resistance is less)

73
Q

What is turbulent flow? Where is it localised to?

A

Air not flowing in parallel layers and becomes chaotic.

Mainly upper airways

74
Q

How does turbulent flow affect resistance?

A

Turbulence leads to greater difference in pressure (between outside air and inside lungs) being needed to maintain air flow which, in turn, increases resistance

Intercostal muscles and diaphragm need to work harder to expand and contract lungs

75
Q

What happens during asthma attack?

A
  • Airways constrict due to increased smooth muscle tone and inflammation within mucosa
  • Can decrease diameter causing resistance to airflow to become high –> turbulent flow
76
Q

During clinical examination, where are breath sounds generated?

A

In the large, upper airways (high flow rate - turbulent flow)

77
Q

What is a vitalograph spirometer used to measure?

A
  1. The forced vital capacity (FVC)

2. The force expiratory volume in 1 second (FEV1)

78
Q

What is a peak flow meter used to measure?

A

Peak expiratory flow rate (PEFR)

79
Q

What is FEV1/FVC ratio used to distinguish between?

A

Obstructive and restrictive conditions

  • Ratio < 0.7 = obstructive
  • Ratio > 0.7 = restrictive
80
Q

What is PEFR used for?

A
  • Convenient way of measuring airways obstruction (not as good as spirometry) as patients can monitor condition at home
  • Wide variations occur, with highest readings in evening and lowest in early morning
81
Q

Describe reversibility of airway constriction in asthma and COPD

A

Asthma –> reversible

COPD –> irreversible

82
Q

Where is the energy used in inspiration to overcome elastic forces stored?

A

As potential energy which is dissipated in expiration

83
Q

What is breathing like in restrictive/constructive conditions?

A

Restrictive –> rapid small volume breaths

Obstructive –> large volume slow breaths

84
Q

What happens do the work done during a respiratory cycle?

A
  • About half is dissipated during inspiration (as heat) to overcome resistance to airflow
  • The remaining energy is stored as potential energy in the elastic structures of the lungs and chest wall, and this stored energy is the driving force for normal expiration
85
Q

What is a flow-volume loop?

A

Describes the pressure and volume changes during inspiration and expiration. The amount of work done is given by the area within the loop.

Flow-volume loops measure the velocity of air flowing through the airways in relation to the volume of air moved during inspiration or expiration.

86
Q

What do the measurements of a flow-volume loop then represent?

A

The measurements therefore reflect both the condition of the conducting airways and lung capacity. Can give idea of where airflow limitation occurs in lungs. Di

87
Q

How can flow-volume loops be used in diagnosis?

A

Different pulmonary diseases give different flow-volume loops

88
Q

What is the purpose of the recoil of the elastic tissues in the lungs?

A

To expel air from the alveoli and airways

89
Q

What is job of external intercostal muscles?

A

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

90
Q

What does fixing the shoulder girdle do? When can this be seen?

A

The pectoralis major and latissimus dorsi muscles pull the ribcage outwards.

Seen hard at work in patients with respiratory distress as in acute asthma, and in athletes at the end of a hard race

91
Q

How else are ribs elevated?

A
  1. Neck muscles pull the ribcage upwards
  2. Sternocleidomastoids elevate the sternum
  3. The scalenus major and minor muscles will elevate both the first two ribs and the sternum
92
Q

What muscles pull the ribcage downwards?

A

The oblique, transversus and rectus abdominis muscles

93
Q

How much does diaphragmatic/ribcage movement contribute to the increase in thoracic volume?

A

Diaphragmatic –> 75%

Ribcage –> 25%

94
Q

Why is less diaphragmatic movement required to expand the thoracic cavity in the upright position than the supine position?

A

In an upright posture, the abdominal contents sink under gravity, as does the diaphragm. The diaphragm flattens out, increasing its cross-sectional area so the diaphragmatic movement required to achieve expansion of the thoracic cavity is smaller than that required to achieve the same expansion in the supine posture, when the diaphragm is more dome-shaped.

95
Q

What is shape of diaphragm in supine/upright position?

A

More dome-shaped

Flattens out

96
Q

Describe the airways in the upright posture

A

The airways in the dependent, lowest, parts of the lungs are compressed and narrowed by the weight of the overlying tissues

In these regions, expiration will reduce the volume of air in an airway to a point where the airway closes (closing capacity)

97
Q

What happens when the closing capacity exceeds the FRC?

A

Begins to compromise gas exchange

98
Q

What is the total lung capacity (TLC)?

A

The maximum amount of gas the lungs can accommodate –> the sum of the 4 volumes (VC + RV). About 6 L

99
Q

What is the forced vital capacity (FVC) or vital capacity (VC)?

A

The maximum possible breath that can be taken (typically 5 L)

Made up of 3 volumes (inspiratory reserve volume, expiratory reserve volume, tidal volume)

100
Q

Why is intrapleural pressure normally subatmospheric?

A

Because of the elastic recoil of the lungs continually trying to separate the 2 layers

101
Q

What is the lung volume?

A

The amount of gas that can be moved with respiration (depends on inspiratory and expiratory effort)

102
Q

Definition of pulmonary ventilation

A

The amount of gas moved in or out of the lungs per minute

103
Q

At rest, what is the work performed by the muscles of respiration?

A

Between 2% and 5% of the resting O2 consumption

104
Q

In normal individuals with maximal hyperventilation, what is the work of breathing?

A

About 30% of the resting O2 consumption

105
Q

What is most of the resistance to airflow in the lungs offered by?

A

The large airways, trachea and bronchi (of more than 2mm diameter) rather than the smaller airways

106
Q

Why do the smaller airways offer less resistance?

A

There are many more smaller airways in parallel so the effective cross-sectional area is much larger at lower points in the tracheobronchial tree

107
Q

What are the 8 functions of the lungs?

A
  1. Gas exchange
  2. Act as reservoir of blood
  3. Conversion of angiotensin I to II
  4. Expulsion of air to produce sound and speech
  5. Filtration of small blood clots from blood to stop them entering systemic circulation
  6. Secretion of immunoglobulin (mainly IgA) into bronchial mucus in response
  7. Local production of surfactant to decrease surface tension in alveolar cells
  8. Maintenance of acid-base balance by excretion of CO2
108
Q

What are the intercostal nerves?

A

Part of the somatic nervous system

Arise from the anterior rami of the thoracic spinal nerves from T1 to T11

109
Q

What are the intercostals supplied/drained by?

A

Intercostal arteries/veins

110
Q

What is FEV1?

A

Forced expiratory volume in one second, is the volume of breath exhaled with effort in that timeframe

111
Q

What is FVC?

A

Forced vital capacity, is the full amount of air that can be exhaled with effort in a complete breath

112
Q

What is the FEV1/FVC ratio?

A

A measurement of the amount of air you can forcefully exhale from your lung

Yr 2 - Respiratory System (22 decks)

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