Mechanics of Breathing, Pressures and Work Flashcards
(81 cards)
1
Q
What does ventilation mean?
A
- movement of air in and out of the lungs
2
Q
What does respiration mean?
A
- gas exchange - respiratory and circulatory systems working together
3
Q
What is external respiration?
A
- gas exchange outside of the lungs - mouth for example
4
Q
What is cellular respiration?
A
- gas exchange at a cellular level - capillaries for example
5
Q
What is lung compliance?
A
- the ability of the lungs to stretch - aim is to increase lung volume
6
Q
What is elastic recoil?
A
- the resistance of the lungs to stretch - aim to passively force air out of lungs
7
Q
Are the lungs more elastic of compliant?
A
- roughly equal
8
Q
What is the formula for compliance?
A
- 🔼 volume / 🔼 pressure
9
Q
What is the relationship between compliance and volume and pressure?
A
- direct relationship between volume + compression - indirect relationship between pressure + compression
10
Q
What is the formula for elasticity?
A
- 🔼 pressure / 🔼 volume
11
Q
What is the relationship between elasticity and volume and pressure?
A
- direct relationship between pressure + elasticity - indirect relationship between volume + elasticity
12
Q
What is pulmonary fibrosis?
A
- parenchymal tissue replaced by stiff fibrous tissue
13
Q
What does pulmonary fibrosis do to compliance and elasticity?
A
- ⬇️ in compliance - ⬆️ in elasticity - difficult to get air in so restrictive disease
14
Q
What may neuronmuscular disorders do to the respiratory tract?
A
- lack of innervation to diaphragm and/or intercostal muscles - ⬇️ in compliance - ⬆️ in elasticity
15
Q
Cystic fibrosis and bronchitis causes a build up in mucus in the lungs making it difficult to get air out of the lungs, meaning they are obstructive diseases, what do these conditions do to compliance and elasticity of the lungs?
A
- ⬆️ in compliance - ⬇️ in elasticity - air can enter but not leave
16
Q
In children born prematurely, a lack of surfactant secretion in the lungs can cause the lungs to collapse, this is called infant respiratory syndrome. What does this do to compliance and elasticity of the lungs?
A
- ⬇️ in compliance - ⬆️ in elasticity - difficult to get air in
17
Q
What is transpulmonary pressure?
A
- difference in pressure between alveoli and intrapleural pressure in the pleural cavity
18
Q
What is transthoracic pressure?
A
- difference in pressure between the intrapleural pressure in the pleural cavity and the pressure at the body surface
19
Q
What does transthoracic pressure represent in breathing?
A
- total pressure required to expand or contract the lungs and chest wall
20
Q
What happens to the diaphragm during inspiration and exhalation?
A
- inspiration = diaphragm flattens ⬆️ volume in lungs - expiration = diaphragm curves ⬇️ volume in lungs
21
Q
What happens to the abdominal muscles during inspiration and exhalation?
A
- inspiration = relax ⬆️ volume in lungs - expiration = contract ⬇️ volume in lungs
22
Q
What are the main muscles involves in inspiration?
A
- diaphragm (75% change in the volume) - external intercostals (bucket handle) - accessory muscles (forced inspiration)
23
Q
What are the 2 main accessory muscle used during forced inspiration?
A
- sternomastoid - scalenus
24
Q
Where are the sternomastoid muscles used during forced inspiration?
A
- insert at the mastoid of cranium (near ear)
- origin at munubrium of sternum and medial clavicle
25
Where are the scalenus muscles used during forced inspiration?
- scalenus = greek for ladder
- 3 muscles (anterior, medial, posterior)
- attach at C4-C6 and ribs 1 and 2
26
What does Boyles law say in relation to pressure and volume?
- if pressure ⬆️ then volume ⬇️
- if volume ⬆️ then pressure ⬇️
27
What is intrapulmonary pressure?
- the pressure within the pleural cavity - essentially the lungs
28
What is intrapleural pressure?
- the pressure within the pleural space - between visceral and parietal pleura
29
What is atmospheric measure?
- pressure at sea level
30
As we inhale and increase the volume in the lungs, what happens to the intrapleural pressure?
- volume in lungs ⬆️
- intrapleural pressure ⬇️
- Boyles law = ⬆️ volume = ⬇️ pressure
31
What is the calculation for transpulmonary pressure?
- intrapulmonary pressure (in lungs)
- intrapleural pressure (in pleural space)
- 760mmHg - 756mmHg = 4mmHg during normal breathing
32
What is the calculation for transthoracic pressure?
- intrapleural pressure (pleural space) - atmospheric pressure
- 756mmHg - 760mmHg = -4mmHg during normal breathing
33
Generally, intrapleural pressure is always negative, how does the lung elasticity contribute towards this?
- wants to shrink and pull the lungs inwards - parietal pleura wants to pull out - ⬆️ volume = ⬇️ pressure - ⬇️ volume and ⬆️ pressure
34
Generally, intrapleural pressure is always negative, how does the lung surface tension contribute towards this?
- wants to shrink and pull the lungs inwards - ⬇️ volume and ⬆️ pressure
35
Generally, intrapleural pressure is always negative, how does the elasticity of the thoracic wall contribute towards this?
- wants to move outwards increasing pleural space and lung volume - ⬆️ volume and ⬇️ pressure
36
What will happen if there is too much fluid in the parietal space?
- it will increase intrapleural space - places pressure on lungs
37
How do the lungs maintain fluid in the parietal space?
- mesoethial cells secrete fluid - lymphatic capillaries drain fluid
38
What are the normal pressures we would expect during inspiration in the atmospheric, intrapulmonary and intrapleural space?
- atmospheric pressure = 760mmHg
- intrapulmonary pressure - 759mmHg
- intrapleural pressure = 756mmHg
39
What stops the pleural space and thoracic wall friction?
- visceral pleura
40
How can airway radius affect inspiration and expiration?
- large airways = lower resistance and breathing is fine - small airway = high resistance and difficulty breathing
41
What happens to the radius of airways during allergic reactions?
- airways become inflamed and swollen - radius ⬇️ and resistance ⬆️ = ⬇️ gas flow
42
What does the force required for inspiration need to overcome?
- elastic recoil
43
In the conducting zone, what is secreted on to the epithelial cells that can add resistance to the airway passing through?
- mucosa causes friction
44
What is airway resistance?
- difference in pressure between alveoli and mouth
- difference in pressure is then divided by flow
45
When calculating airway resistance, but you do not have flow, but you have resistance and pressure differences, what is the formula to calculate flow?
- flow = 🔼 pressure / resistance
46
What is the relationship between gas flow and pressure?
- direct association - if pressure ⬆️ = ⬆️ in flow - if pressure ⬇️ = ⬇️ in flow
47
What is the relationship between gas flow and resistance?
- inverse association - if resistance ⬆️ = ⬇️ in flow - if resistance ⬇️ = ⬆️ in flow
48
What is a generation in the respiratory tract?
- a division of the respiratory tract
- carina divides into left and right bronchi is a generation
49
On average, how many generations are in the respiratory tract?
- 23
50
What are the 2 terms used to describe different airflow through the respiratory tract?
- laminar (fluid and low resistance)
- turbulent (disrupted and increased resistance)
51
What is laminar flow in the respiratory tract?
- smooth flow with no resistance - proportional to the radius
52
What is turbulent flow in the respiratory tract?
- irregular flow with resistance - increased resistance
53
What is surface tension in the alveoli?
- H2O creates attractive forces (hydrogen bonds)
- strongest forces pull H20 molecules down
- at air/water interface water retreats downwards
54
Why are the bonds to the side and below H2O molecules stronger than those at the top of the H2O?
- H2O cannot bind with air
- makes bonds below and to the side stronger
- thus increasing surface tension
55
In instances where the surface tension is high in the alveoli, what does that do to the alveoli?
- H2O retracts pulling down towards the alveoli
- alveoli shrink and recoil into smallest possible size
- this increases the collapsing pressure of the alveoli
- poor gas exchange/perfusion takes place
56
What is the formula for calculating pressure in relation to surface tension and radius?
- P = pressure T = surface tension r = radius - P = 2T/r
57
What is the relationship between pressure and radius?
- inverse relationship - ⬆️ pressure = ⬇️ radius - ⬇️ pressure = ⬆️ radius
58
If surface tension is reduced, what happens to the pressure?
- ⬇️ in surface tension = ⬇️ in pressure - this reduces the risk of alveoli collapse
59
If surface tension increases, what happens to the pressure?
- ⬆️ in surface tension = ⬆️ in pressure - this increases the risk of alveoli collapse
60
What is surfactant?
- fatty acids and proteins
- dipalmitoyl phosphatidycholine (DPPC)
- dipalmitoyl = 2 (di) palmitic acid groups for tails
- phosphatidycholine = phosphate, choline, glycerole head
61
How does surfactant interact with H2O?
- surfactant is amphipathic (H20 loving and hating)
- dipalmitoyl tails are hydrophobic
- phosphatidycholine head is hydrophillic
62
How does surfactant reduce surface tension?
- head interacts with water at surface
- tails try to pull away from the water
- pulling away from water raises the water and reduces surface tension
63
In small and large alveoli, is the surfactant evenly distributed?
- no - small = yes - larger = surfactant is spread throughout
64
If the surfactant is not evenly distributed throughout, due to the differing sizes of the alveoli, the surface tension may be lower in small alveoli compared to larger alveoli. Why is this a good thing?
- helps maintain overall homeostasis of the lungs - balanced surface tension throughout
65
If the radius of the alveoli is small with limited surfactant, what does that mean for the pressure in the alveoli?
- ⬇️ radius = ⬆️ pressure
66
If the radius of the alveoli is small with sufficient surfactant, what does that mean for the pressure in the alveoli?
- ⬇️ radius + surfactant = ⬇️ pressure
67
What are the 2 main contributors to keeping alveoli open?
- transmural pressure gradient (intrapulmonary/intrapleural)
- pulmonary surfactant
68
What are the 2 main contributors that promote the collapse of the alveoli?
- elastic recoil of pulmonary tissue (alveoli)
- increased alveolar surface tension
69
What is Consideration of Work of Breathing?
- energy required to stretch elastic tissues of chest and lungs
- energy required to move air and non-elastic tissues through tubes
70
What is Consideration of Work of Breathing measured in?
- joules/litre
71
What are the 3 elastic work aspects of Consideration of Work of Breathing (energy required for breathing) measured in?
1 - respiratory muscles 2 - length/tension relationships 3 - fatigue
72
What are the 2 non-elastic work aspects of Consideration of Work of Breathing measured in?
1 - viscous resistance 2 - airway resistance
73
Using the 2 terms used to describe different airflow, turbulent and laminar, through the respiratory tract, what flow would patients with respiratory tract disease have?
- turbulent flow - rapid respiratory rate
74
What can happen in relation to Consideration of Work of Breathing (energy needed to breathe) in respiratory disease, which require a lot of energy to breathe?
- consideration in lungs is increased due ⬆️ repiratory rate
- increased elastic recoil also increases consideration
- increased consideration increases fatigue
- some patients may need a ventilator
75
What is tidal volume?
- what we inspire and expire at rest - aprox 500ml
76
What is inspiratory reserve volume?
- forced/maximal inspiration above tidal volume
- aprox 3000ml
77
What is expiratory reserve volume?
- forced expiration below tidal volume
- aprox 800-1200ml
78
What is residual volume?
- air remaining in lungs following forced expiration
- almost impossible to exhale all air
79
What is inspiration capacity?
- total inspiration capacity of lungs
- tidal volume + inspiratory reserve volume
80
What is functional residual volume?
- total expiration capacity of the lungs
- expiratory reserve volume + residual volume
81
What is vital capacity?
- total air that can be inhaled and expelled
- inspiratory reserve volume + expiratory reserve volume + tidal volume
