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A2. Respiratory System > Respiratory Physiology > Flashcards

Respiratory Physiology Flashcards

1
Q

What are the 4 functions of the respiratory system?

A

Gas exchange
Acid base balance
Protection from infection
Communication via speech

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2
Q

What gas is added from the air to the blood?

A

O2

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3
Q

What gas is removed from the blood into the air?

A

CO2

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4
Q

What is the respiratory system responsible for?

A

Acquiring oxygen

Removing carbon dioxide

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5
Q

What system does the respiratory system need?

A

The cardiovascular system

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6
Q

Where does the cardiovascular system transport oxygen?

A

To tissues

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7
Q

Where does the cardiovascular system transport carbon dioxide?

A

Away from tissues

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8
Q

What does cellular respiration need?

A

Oxygen

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9
Q

What is the waste product of cellular respiration?

A

Carbon dioxide

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10
Q

Where does the pulmonary artery travel?

A

Away from the heart

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11
Q

Where does the pulmonary vein travel?

A

Towards the heart

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12
Q

What is the function of pulmonary circulation?

A

Deliver CO2 to lungs and pick up O2

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13
Q

What is the function of systemic circulation?

A

Deliver O2 to cells

Remove CO2 from cells

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14
Q

In the steady state what is the relationship between the gases exchanged in the lungs and tissue?

A

The net volume of oxygen and carbon dioxide exchanged in the lungs per unit of time is equal to the net volume exchanged in the tissues

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15
Q

What does gas exchange being equal in the lungs and tissues prevent?

A

The build up of gas in the circulation

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16
Q

What is the main organ of the respiratory system?

A

Lungs

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17
Q

What is a common name for the larynx?

A

Voice box

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18
Q

Where does air enter the body?

A

Through the nose

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19
Q

How many trachea are there?

A

1

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20
Q

How many bronchus are there?

A

2

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21
Q

What is the epiglottis?

A

Small flap of tissue that folds over the trachea preventing food from entering the air pipe when you swallow

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22
Q

What does the upper respiratory system compose of?

A

Mouth
Nasal cavity
Pharynx
Larynx (voice box)

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23
Q

What does the lower respiratory system compose of?

A

Trachea
Bronchi
Lungs

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24
Q

How is the patency of airways maintained?

A

By C shaped rings of cartilage

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25
Q

Where can gas exchange occur?

A

Alveoli

Systemic Capillaries

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26
Q

What organ lying inferior to the right lung causes is to be shorter and broader?

A

The liver

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27
Q

What are the 2 fissures of the right lung?

A

Horizontal fissure

Oblique fissure

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28
Q

How many bronchi does the trachea branch into?

A

2

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29
Q

How many more times does each bronchus branch?

A

22

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30
Q

Where does the bronchus terminate?

A

At the alveoli

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31
Q

Why are the alveoli covered in capillaries?

A

To minimise the distance of exchange

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32
Q

What are the alveoli covered in?

A

Elastic fibres

Capillaries

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33
Q

Describe the walls of the alveoli?

A

Thin walls

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34
Q

Why does gas not exchange at the upper airways?

A

Because the walls are too thick

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35
Q

What is the air in the upper airways known as and why?

A

Anatomical dead space

Because it cannot participate in gas exchange

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36
Q

What features of the alveoli make it so effective for gas exchange?

A

Thin walls

Large surface area

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37
Q

What is airway diameter altered by?

A

Activity of bronchial smooth muscle

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38
Q

What is the function of mucous in the respiratory tract?

A

To moisten the air
To trap large and invasive particles
To provide a large surface area for cilia to work on

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39
Q

What cells produce mucous in the respiratory tract?

A

Goblet cells

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40
Q

What type of epithelium lines the respiratory tract?

A

Psuedo-stratified, ciliated, columnar

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41
Q

What hair like structures line the respiratory tract?

A

Cilia

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42
Q

In terms of pressure how do gases move?

A

From an area of high pressure to an area of low pressure

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43
Q

What does Boyle’s Law state?

A

The pressure exerted by a gas is inversely proportional to its volume

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44
Q

What does Daltons Law state?

A

The total pressure of a gas mixture is the sum of the pressure of the individual gases

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45
Q

What does Charles Law State?

A

The volume occupied by a gas is directly related to the absolute temperature

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46
Q

What is the lower respiratory system bound by?

A

Diaphragm
Spine
Ribs

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47
Q

How many lobes is the right lung split into?

A

3

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48
Q

How many lobes is the left lung split into?

A

2

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49
Q

What volume of pleural liquid is there in the pleural cavity?

A

3ml

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50
Q

What is function of pleural liquid?

A

To act as a lubricant

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51
Q

How many pleural membranes is each lung enclosed by?

A

2

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52
Q

What are the 2 pleural membranes?

A

Parietal pleura

Visceral pleura

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53
Q

What is inflammation of the pleural membranes known as?

A

Pleurisy

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54
Q

What is the purpose of the pleural membranes?

A

To anchor the lungs to the rib cage

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55
Q

What does the parietal pleural membrane coat?

A

The inner surface of the lungs

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56
Q

What does the visceral pleural membrane coat?

A

The outer surface of the lungs

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57
Q

Explain pneumothorax

A

When there is a loss of relationship of the pleural membranes
The chest wall wants to expand
The lung wants to shrink
Leads to the collapse of the lung

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58
Q

What muscles are used for inspiration?

A

Diaphragm
External intercostal muscles
Scalenes
Sternocleidomastoids

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59
Q

What muscles are used for expiration?

A

Internal intercostal

Abdominals

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60
Q

What is the very basic concept of breathing?

A

There is an increase of volume in the thoracic cavity
This decreases the pressure
Drawing air from higher pressure outside in

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61
Q

Is inspiration passive?

A

No

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62
Q

Is expiration passive?

A

Yes - AT REST

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63
Q

When the diaphragm contracts what happens?

A

It moves down

Increasing thoracic volume

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64
Q

What is the intra-thoracic (alveolar) pressure?

A

The pressure inside the thoracic cavity

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65
Q

Is the intra thoracic pressure + or -?

A

Can be either compared to the atmospheric pressure

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66
Q

What is the intra-pleural Pressure?

A

Pressure inside pleural cavity

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67
Q

Should the intra-pleural pressure be + or -?

A

Always negative (in healthy lung at least)

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68
Q

What is the transpulmonary pressure?

A

Difference between the alveolar pressure and intra-pleural pressure

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69
Q

What is the major determinant of airway resistance?

A

The radii of the airways

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70
Q

Are the lungs elastic?

A

Yes they are elastic structures

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71
Q

Explain expiration

A

The inspiratory muscles cease to contract
Allowing elastic recoil of chest wall
Lungs return to normal size
Smaller volume - greater pressure than atmospheric
Driving air out of the lungs

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72
Q

What do type I alveolar cells do?

A

Permit gas exchange

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73
Q

What do type II alveolar cells do?

A

Secrete surfactant fluid

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74
Q

What volume of gas does the average person breathe in and out in a breath?

A

500ml

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75
Q

What is tidal volume?

A

The normal inspiration and expiration of gas

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76
Q

What is the average volume of tidal volume?

A

500ml

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77
Q

What volume of air is the anatomical dead space?

A

Around 150ml

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78
Q

What volume is the inspiratory reserve volume?

A

3L

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79
Q

What volume is the expiratory reserve volume?

A

1.1L

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80
Q

Why is the residual volume in the lungs so crucial?

A

Prevents the alveoli from collapsing

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81
Q

What is the vital capacity?

A

The maximum expiration after the maximum inspiration

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82
Q

What is pulmonary ventilation?

A

Total air movement into-out of the lungs

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83
Q

What is alveolar ventilation?

A

The fresh air getting to alveoli and therefore available for gas exchange

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84
Q

Is the anatomical dead space air available for gas exchange?

A

No

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85
Q

Between what volumes do the lungs normally operate?

A

2.3L and 2.8L

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86
Q

How do you work out the air that reaches the alveoli?

A

Vol of air breathed in - 150ml of the dead space air

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87
Q

What affects the amount of air that reaches the alveoli? Rate or depth of breathing?

A

Depth

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88
Q

What do type I alveolar cells permit?

A

Gas exchange

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89
Q

What do type II alveolar cells secrete?

A

Surfactant fluid

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90
Q

What does surfactant fluid reduce?

A

Surface tension on alveolar surface

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91
Q

What does the compliance of the lung represent?

A

The stretchability of the lung

How easy it is for air to get into the lungs

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92
Q

Is low compliance good or bad?

A

Bad

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93
Q

What happens to the compliance of our lungs with age?

A

Become less compliant

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94
Q

Describe high compliance?

A

Large increase in lung volume for small decrease in ip pressure

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95
Q

Describe low compliance?

A

Small increase in lung volume for large decrease in ip pressure

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96
Q

What is the definition of compliance?

A

The change in volume relative to the change in pressure

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97
Q

During inspiration what needs to be overcome?

A

Surface tension

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98
Q

What does a shallower curve represent?

A

Lower compliance

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99
Q

What does a steeper curve represent?

A

Higher compliance

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100
Q

What is emphysema?

A

Loss of elastic tissue meaning expiration requires effort

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101
Q

What is fibrosis?

A

Inert fibrous tissue means effort of inspiration increases

As the stretchability of the lung is affected

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102
Q

What is the pleural membrane coating the outer surface of the lungs?

A

Visceral membrane

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103
Q

What is the pleural membrane coating the inner surface of the ribs?

A

Parietal membrane

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104
Q

Is inspiration passive?

A

No

Inspiration requires energy

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105
Q

Upon inspiration does the diaphragm ascend or descend?

A

Descend

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106
Q

Why does the diaphragm descend upon inspiration?

A

To increase thoracic volume

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107
Q

What happens with asthma?

A

There is an over-reactive constriction of bronchial smooth muscle.
Increasing resistance making expiration of air difficult

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108
Q

Why is intrapleural pressure always negative?

A

So it acts like a suction to keep the the lungs inflated

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109
Q

What is the bulk flow of air between the atmosphere and alveoli proportional to?

A

The difference between the atmospheric and alveolar pressures

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110
Q

What is the bulk flow of air between the atmosphere and alveoli inversely proportional to?

A

Airway resistance

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111
Q

Describe the end of a unforced expiration

A

The dimensions of the lung and thoracic cage are stable as the result of opposing elastic forces
The lungs are stretched and attempt to recoil
The chest wall is compressed and attempting to move outwards

112
Q

What is the major determinant of airway resistance?

A

The radii of the airways

113
Q

What does airway resistance determine?

A

How much air flows into the lungs at any given pressure

114
Q

Does the increase in thoracic volume make the intrapleural pressure more negative or positive?

A

Negative

115
Q

What is vital capacity?

A

Tidal volume
+ ERV
+ IRV

116
Q

What is TLC?

A

Total lung capacity

Vital capacity + Residual volume

117
Q

At birth what volume do babies lack?

A

Residual volume

118
Q

What is hyperventilation?

A

When more air than normal reaches the alveoli

I.e when taking deep breaths

119
Q

What is hypoventilation?

A

When less air than normal reaches the alveoli

I.e when taking shallow breaths

120
Q

How do you measure the air to alveoli?

A

The tidal volume minus 150ml

121
Q

What unit is pressure commonly expressed in?

A

mmHg

122
Q

During hyper ventilation what does PO2 rise to?

A

120mmHg

123
Q

During hyper ventilation what does PCO2 fall to?

A

20 mmHg

124
Q

During hypo ventilation what does PO2 fall to?

A

30 mmHg

125
Q

During hypo ventilation what does PCO2 rise to?

A

100mmHg

126
Q

Why is the residual volume impossible to squeeze out ?

A

It stops the alveoli from collapsing

127
Q

What is ventilation?

A

The movement of air in and out of the lungs (breathing)

128
Q

What percentage of air in the alveoli is fresh?

A

70%

129
Q

What cells produce surfactant?

A

Type II alveolar cells

130
Q

What is the role of pulmonary surfactant?

A

To act like a detergent
Reducing the surface tension on the alveolar surface
Reducing the tendency for the alveoli to collapse

131
Q

What molecular interactions of the alveoli does pulmonary surfactant interrupt?

A

Acts like a detergent

Interfering with the water molecule interactions on the alveoli

132
Q

Why does pulmonary surfactant increase the compliance of the lungs?

A

As it reduces the lungs tendency to recoil

You do not have to apply extra pressure to stop the alveoli from collapsing

133
Q

When does surfactant pulmonary production start?

A

25 weeks

134
Q

Normally what is the expectation of healthy lungs regarding compliance?

A

Expected to be highly compliant

135
Q

Is compliance related to elasticity or stretchability?

A

Stretchability

136
Q

Describe high compliance of the lungs?

A

A large increase in lung volume for small decrease in ip pressure

137
Q

Describe low compliance of the lungs?

A

A small increase in lung volume for large decrease in ip pressure

138
Q

Why is low compliance bad?

A

Requires alot of effort for a small increase in lung volume

139
Q

Does compliance increase or decrease with age?

A

Decrease

140
Q

Where is alveolar ventilation greatest?

A

At the base of the lung

141
Q

Where is alveolar ventilation the least?

A

At the apex of the lung

142
Q

Why is alveolar ventilation greatest at the base of the lung?

A

Because the weight of the lung is pushing down on the base

Meaning the base of the lung has more potential to expand

143
Q

What does a shallower curve in pressure volume graph indicate?

A

Lower compliance

144
Q

What does a steeper curve on pressure volume graph indicate?

A

Higher compliance

145
Q

What does low compliance indicate?

A

A stiff lung

146
Q

What does high compliance indicated?

A

A pliable lung

147
Q

What is obstructive lung disease?

A

When there is obstruction to the flow of air especially on expiration

148
Q

Does obstructive lung disease particularly affect inspiration or expiration?

A

Expiration

149
Q

What does restrictive lung disease restrict?

A

Lung expansion

Compliance

150
Q

What happens to alveolar ventilation from the base to the apex of the lung?

A

It declines

151
Q

What happens to compliance from the base to the apex of the lung?

A

It declines

152
Q

Give 2 examples of obstructive lung disorders

A

Asthma
COPD
Chronic bronchitis
Emphysema

153
Q

What is lost in emphysema?

A

Lung elasticity

154
Q

What is chronic bronchitis?

A

Inflammation of the bronchi

155
Q

What is infant respiratory distress syndrome?

A

When there is insufficient surfactant production in the babies lungs
Surfactant production normally occurs at around 23 weeks

156
Q

What is oedema of the lungs?

A

Build up of fluid around the alveoli

157
Q

Is oedema restrictive or obstructive?

A

Restrictive

158
Q

What test is used to measure lung function?

A

Spirometry

159
Q

Is voluntary or involuntary lung action measured with a spirometer?

A

Voluntary

160
Q

What can be measured using spirometry?

A

Tidal volume
Inspiratory RV
Expiratory RV
Vital Capacity

161
Q

What is FEV1?

A

The forced expiratory volume in 1 second

162
Q

What is FVC?

A

The forced vital capacity

163
Q

In healthy individuals what should the forced expiratory volume be?

A

80% of the vital capacity

164
Q

Why does obstructive lung disease show a decrease in Vital capacity and FEV?

A

Because obstruction means they cannot blow as much air out in 1 second

165
Q

Why does restrictive lung disease show an increase in %?

A

Because the problem was getting the air in

Meaning they can get the air out quicker as they technically do not have enough in their lungs to begin with

166
Q

What are the 2 different blood supplies to the lungs?

A

Bronchial circulation

Pulmonary circulation

167
Q

What is the bronchial circulation supplied by?

A

The bronchial arteries

It is the nutritive one

168
Q

Explain bronchial circulation

A

Arises from systemic circulation

Supplies oxygenated blood to the airways smooth muscle, nerves and lung tissue

169
Q

What is the pulmonary circulation used for?

A

Gas exchange

170
Q

Is the pulmonary circulation a high or low pressure system?

A

Low

171
Q

Is the pulmonary circulation a high or low flow system?

A

High

172
Q

Where do the left and right pulmonary arteries arise from?

A

Right ventricle

173
Q

Where does the pulmonary circulation return oxygenated blood to via what?

A

To the left atrium

Via the pulmonary vein

174
Q

How does gas exchange occurs at the alveoli and tissues?

A

The gas moves from a high partial pressure to a low partial pressure

175
Q

What is the partial pressure of O2 and CO2 in the pulmonary vein?

A

100mmHg for O2

40mmHg for CO2

176
Q

What is the partial pressure of O2 at the tissues?

A

40mmHg

177
Q

Explain O2 partial pressure at the tissues?

A

High O2 pressure in blood (100mmHg)
Low partial O2 pressure in tissues (40mmHg)
Moves down pressure gradient

178
Q

Explain CO2 partial pressure at the tissues?

A

Low CO2 partial pressure in blood (40mmHG)
High CO2 partial pressure in tissues (46mmHg)
CO2 moves into blood down pressure gradient

179
Q

What does A stand for?

A

Alveolar pressure

180
Q

What does a stand for?

A

Arterial pressure

181
Q

What does v stand for?

A

Mixed venous blood

182
Q

What does PaO2 stand for?

A

Partial pressure of oxygen in arterial blood

183
Q

What does PACO2 stand for?

A

Partial pressure on carbon dioxide in alveolar air

184
Q

What rules does the diffusion of gas between the alveoli and blood follow?

A

The rules of simple diffusion

Moving down its partial pressure gradient

185
Q

What is the rate of gas diffusion directly proportional to?

A

Partial pressure gradient
Gas solubility
Available surface area

186
Q

What is the rate of gas diffusion inversely proportional to?

A

The thickness of the membrane

187
Q

Why is the rate of O2 and CO2 diffusion similar even though O2 has a much steeper conc. gradient?

A

Because CO2 is much more soluble than O2 therefore diffusing faster

188
Q

How thick is the alveolar membrane?

A

Thin as possible

Only one cell thick

189
Q

Where are the alveoli directly located by and why?

A

Blood vessels to decrease the distance needed for gas exchange

190
Q

Why does the alveolar surface have a large surface area?

A

To allow maximum rate of diffusion of gases

191
Q

How does emphysema affect gas exchange?

A

Destructs alveoli

Less surface area for gas exchange

192
Q

How does fibrotic lung disease affect gas exchange?

A

Thickened alveolar membrane slows gas exchange

193
Q

How does pulmonary oedema affect gas exchange?

A

Fluid build up increases diffusion distance

194
Q

What causes fibrosis?

A

Thickened walls of alveoli due to fibrosis tissue

195
Q

What is shunt?

A

A term used to describe the passage of blood though areas of the lung that are poorly ventilated

196
Q

Is inspiration controlled by smooth or skeletal muscle?

A

Skeletal

197
Q

What nerves innervate the diaphragm?

A

Phrenic nerves

198
Q

What controls the innervation of the muscles of breathing?

A

Pons, medulla

199
Q

From which vertebral levels do the phrenic nerves originate?

A

C3,4,5

200
Q

Do we have any voluntary control over our breathing?

A

Yes

201
Q

What modulates our breathing?

A

Emotion
Voluntary Over ride
Chemical composition of blood
Mechano-sensory input

202
Q

What is the most significant input that changes our breathing?

A

Chemoreceptor input

203
Q

What are the two types of chemoreceptors?

A

Central

Peripheral

204
Q

Where are central chemoreceptors located?

A

Medulla

205
Q

Where are peripheral chemoreceptors located?

A

Carotid and aortic

206
Q

What do central chemoreceptors reflect?

A

CO2

207
Q

What do peripheral chemoreceptors respond to?

A

Plasma (H+) and PO2

208
Q

What fluid bathes the central nervous system?

A

CSF

Cerebral spinal fluid

209
Q

Can the brain and spinal cord tolerate much change to their environment (CSF)?

A

No

210
Q

What is the blood brain barrier?

A

A selective barrier that protects the brain by only letting certain things cross

211
Q

Is the blood brain barrier permeable to gas?

A

Yes

212
Q

Is the blood brain barrier permeable to ions?

A

No

213
Q

When arterial PCO2 increases what crosses the blood brain barrier?

A

CO2

214
Q

What effect does an increase in arterial PCO2 have?

A

Feedback system

Increases ventilation

215
Q

What effect does a decrease in arterial PCO2 have?

A

Feedback system

Slows ventilation rate

216
Q

Below what level does haemoglobin lose a lot of saturation?

A

60mmHg

217
Q

What happens when PO2 mmHg falls below 60mmHg?

A

There is a significant increase in ventilation as an attempt to get more O2 into the body
Restoring normal O2

218
Q

Do alveoli have a small or large surface area?

A

Large

219
Q

Describe the thickness of the membrane at the alveoli?

A

Thin membrane

220
Q

What is perfusion?

A

The process of the body delivering blood to a capillary bed in its biological tissue

221
Q

Is blood flow at the base of the lungs high or low and why?

A

High because arterial pressure exceeds alveolar pressure

222
Q

Is vascular resistance at the base of the lung high or low?

A

Low

223
Q

Is the blood flow at the apex of the lungs high or low?

A

Low because arterial pressure is less than alveolar pressure

224
Q

Is vascular resistance at the apex of the lungs high or low?

A

Higher

225
Q

If ventilation decreases what happens at the capillary bed?

A

PCO2 increases
PO2 decreases
Blood flowing past those alveoli does not get oxygenated

226
Q

What is shunting?

A

Dilution of oxygenated blood from better ventilated areas

227
Q

When hypoxia is detected why do blood vessels in the lungs constrict?

A

To allow less blood to flow to the poorly oxygenated ares

228
Q

What happens to blood vessels in the rest of the body when hypoxia is detected?

A

They dilate

229
Q

What nerves stimulate the external intercostal muscles?

A

Intercostal nerves

230
Q

Where is emotion in the brain controlled?

A

Limbic system

231
Q

Where does a rise in (H+) conc. come from?

A

CO2

232
Q

If there is increased ventilation is more CO2 blown off or retained?

A

Blown off

233
Q

If there is decreased ventilation is more CO2 blown off or retained?

A

Retained

234
Q

Why can’t you stop yourself breathing and kill yourself?

A

Because after you have been knocked unconscious the innate breathing system will kick in and begin breathing again

235
Q

What is ventilation reflexly inhibited by?

A

Increase in arterial PO2 or a decrease in arterial PCO2

236
Q

When else is respiratory inhibited?

A

During swallowing to avoid aspiration of food or fluids

237
Q

What is swallowing folloed by?

A

Expiration

238
Q

Why is swallowing followed by expiration?

A

To dislodge outwards particles from the region of the glottis

239
Q

What volume of O2 dissolves in 1L of water?

A

3ml

240
Q

What does haemoglobin increase the carrying capacity of O2 to?

A

3ml to 200ml per litre

241
Q

What cells is haemoglobin found in?

A

Red blood cells

242
Q

What would gaseous phase gases travelling in the blood cause?

A

Bubbles in the blood causing fatal air embolism

243
Q

What is the resting oxygen demand of tissues?

A

250ml/min

244
Q

What % of O2 is extracted by peripheral tissues at rest?

A

25%

245
Q

Whats the difference between HbA and HbA2?

A

Where delta chains replace beta chains

246
Q

Whats the difference between HbA and HbF?

A

Where gamma chains replace beta chains

247
Q

What is glycosylated Hb associated with?

A

Glucose

248
Q

Is the glycolysation of Hb reversible?

A

No it is irreversible

249
Q

What is the major determinant of the degree to which haemoglobin is saturated?

A

The partial pressure of oxygen in the arterial blood

250
Q

How many subunits is haemoglobin composed of?

A

4

251
Q

When does oxygen stop entering the plasma?

A

When all Hb is saturated

252
Q

How much O2 does each litre of systemic arterial blood contain?

A

200ml

253
Q

At PO2 60mmHg how saturated is haemoglobin?

A

90%

254
Q

Do HbF and myoglobin have a higher or lower affinity for O2 than HbA?

A

Higher

255
Q

Does foetal haemoglobin have a higher or lower affinity than the mothers haemoglobin for oxygen?

A

Higher affinity

256
Q

Why does foetal haemoglobin have a higher affinity for O2?

A

So that it can acquire and pull in O2 from the mothers blood

257
Q

In anaemia is there any problem with ventilation?

A

No

258
Q

In anaemia is there any problem with diffusion?

A

No

259
Q

Even when O2 content is low why can PaO2 be normal?

A

Because the haemoglobin that is present is saturated

260
Q

What is anaemia?

A

Defined as the condition where the oxygen carrying capacity of the blood is compromised

261
Q

What factors can affect haemoglobin affinity?

A

pH
Temperature
CO2
(DPG)

262
Q

How is the affinity of haemoglobin decreased?

A

Decrease in pH
Increase in temperature
Increase in PCO2

263
Q

How is the affinity of haemoglobin increased?

A

Increase in pH
Decrease in temperature
Decrease in PCO2

264
Q

What does an increased affinity of haemoglobin cause?

A

Makes oxygen unloading more difficult

But aids the collection of oxygen in the pulmonary circulation

265
Q

Is shunt perfused or ventilated?

A

Perfused but not ventilated

266
Q

Is alveolar space ventilated or perfused?

A

Ventilated but not perfused

267
Q

What is shunting the opposite to?

A

Alveolar dead space

268
Q

Where does the majority of perfusion-ventilation mismatch occur?

A

At the apex of the lung

269
Q

What should the value of perfusion-ventilation ideally be?

A

1

270
Q

At which level does the trachea bifurcate?

A

T4

271
Q

Which spinal nerves innervate the phrenic nerve?

A

C3,4,5 (keep the diaphragm alive)

272
Q

What is hypoxic hypoxia?

A

This is when PaO2 is below normal

273
Q

What is anaemic hypoxia?

A

This is when the lungs are in perfect working condition however the carrying capacity of )2 of the blood has been reduced

274
Q

What is circulatory hypoxia?

A

This is when the heart cannot pump the blood to the tissues or lungs

275
Q

What is metabolic hypoxia?

A

When oxygen delivery to the tissue does not meet increase demand by cells

276
Q

Describe hypoventilation

A

Causes CO2 retention
Causes increase in H+ conc
Brings about respiratory acidosis

277
Q

Describe hyperventilation

A

Blowing off more CO2,
Decreased H+ conc
Brings about respiratory alkalosis

A2. Respiratory System (15 decks)

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