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Respiratory AM > Respiratory physiology > Flashcards

Respiratory physiology Flashcards

1
Q

What are the functions of the respiratory system?

A

Gas exchange
Acid base balance
Protection from infection
Communication via speech

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2
Q

Why is gas exchange so important?

A

Oxygen is supplied to tissues and CO2 is removed

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3
Q

What is external respiration?

A

Movement of gases between the air and the body’s cells

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4
Q

What do the pulmonary artery and vein carry?

A

Artery- Deoxygenated blood away from the heart

Vein- oxygenated blood towards the heart

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5
Q

Where is the division of the upper and lower respiratory tracts?

A

Larynx

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6
Q

What is the epiglottis and its function?

A

Small flap of tissue that folds over the trachea to prevent food or liquid from entering the airway

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7
Q

At what vertebral level does the trachea bifurcate?

A

T4

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8
Q

What are the lobes of the right lung?

A

Superior
Middle
Inferior

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9
Q

What are the lobes of the left lung?

A

Superior and inferior

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10
Q

What lobes does the horizontal tissue split?

A

Superior and middle

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11
Q

What lobes does the oblique tissue split?

A

Inferior and superior/middle

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12
Q

What does the trachea branch into?

A

Bronchi

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13
Q

What is the carina?

A

Bifurcation of the trachea?

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14
Q

Why do the bronchi and trachea have cartilaginous rings?

A

Maintain patency of the airway

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15
Q

What do the bronchi branch into?

A

Bronchioles

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16
Q

What maintains the patency of the bronchioles?

A

Physical forces from the thorax

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17
Q

Where is the most resistance to airflow present?

A

Trachea and bronchi

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18
Q

What 3 types of cell are resent in the alveoli?

A

Type 1 pneumocytes, type 2 pneumocytes, macrophages

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19
Q

What is the function of type 1 and 2 pneumocytes?

A

1- thin cells that allow for gas exchange

2- produce surfactant

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20
Q

What is the function of surfactant?

A

Reduce surface tension and prevent small alveoli from collapsing

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21
Q

Describe the use of the elastic fibres in the alveoli walls?

A

Stretched during inspiration

Energy invested during inspiration is then released allowing for passive expiration

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22
Q

What kind of epithelium lines the respiratory tract?

A

Pseudostratfied ciliated columnar epithelium

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23
Q

What are the differences in the epithelium travelling down the respiratory tract?

A

Cells become more squamous

Goblet cells then cilia lost

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24
Q

What is the function of mucus in the respiratory tract?

A

Moisten air

Traps particles

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25
Q

What is Boyle’s law?

A

Pressure exerted by a gas is inversely proportional to its volume

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26
Q

What is Dalton’s law?

A

Total pressure of a gas mixture is the sum of the pressures of the individual gases

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27
Q

What is Charles’ law?

A

Volume occupied by a gas is directly related to the absolute temperature

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28
Q

What is Henry’s law?

A

Amount of gas dissolved in a liquid is determined by the pressure of the gas and its solubility in the liquid

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29
Q

What is the hilum of the lung?

A

Site of the root

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30
Q

What is the root of the lung?

A

Entry and exit of major vessels and airways

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31
Q

What structures exist at the root of the lung?

A

Pulmonary arteries and veins

Bronchus

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32
Q

What are the 2 aspects of the pleural membrane?

A

Parietal- lines ribs and diaphragm

Visceral- lines surface of lungs

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33
Q

What is the pleural cavity?

A

The space between the 2 pleural membranes

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34
Q

What is the function of the intrapleural fluid?

A

Allows membranes to glide across each other and prevents membranes from separating

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35
Q

What is pleurisy?

A

Inflammation of the pleural membranes, causing them to grate across each other, causing pain

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36
Q

What creates an equilibrium at the end of a breath?

A

Attachment of the chest wall (that naturally want to expand) to the lungs (that naturally want to recoil) by the pleural membranes

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37
Q

What draws the air into the lungs?

A

The negative pressure in the pleural cavity caused by the equilibrium between the lungs and chest wall

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38
Q

What muscles are used for inspiration?

A

Diaphragm and external intercostals

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39
Q

What muscles are used for expiration?

A

Abdominals and internal intercostals

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40
Q

What are the accessory muscles of inspiration?

A

Scalenes and sternocleidomastoids

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41
Q

What is the intra-thoracic pressure?

A

Pressure inside the thoracic cavity i.e. alveoli

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42
Q

What is the intra pleural pressure?

A

Pressure inside the pleural cavity

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43
Q

What is the transpulmonary pressure?

A

Difference between intra-thoracic and intra-pleural pressure

This is always positive as Pip is more negative than PA

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44
Q

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

A

Difference between the alveolar and atmospheric pressures

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45
Q

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

A

Airway resistance

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46
Q

What happens at the end of a passive expiration?

A

The atmospheric and alveolar pressures are equal, and the dimensions of the thoracic cage and lungs are stable as a result of opposing elastic fibres creating a subatmohpheric intrapleural pressure

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47
Q

What is the major determinant of airway resistance?

A

Radii of airway

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48
Q

What is the anatomical dead space?

A

The volume of gas occupied by the conducting airways- this gas is not available for exchange

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49
Q

What volume of gas is in the anatomical dead space at any one time?

A

About 150ml

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50
Q

How much is tidal volume?

A

500ml between 2.3 and 2.8 litres

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51
Q

What is the residual volume?

A

Volume of gas left in the lungs at the end of expiration to prevent the alveoli from collapsing and provide a reservoir of air for continuous gas exchange

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52
Q

How much is residual volume?

A

1.2 litres

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53
Q

What is inspiratory reserve volume?

A

Additional air that can be forcibly inhaled after inspiration of the normal tidal volume

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54
Q

How much is inspiratory reserve volume?

A

3 litres

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55
Q

What is expiratory reserve volume?

A

Additional air that can be forcibly exhaled after exhalation of the normal tidal volume

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56
Q

How much expiratory reserve volume?

A

1.2 litres

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57
Q

What is the total lung capacity?

A

Maximum amount of air that fills the lungs

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58
Q

How much is total lung capacity?

A

6 litres

59
Q

What is vital capacity?

A

The total amount of breath that can be exhaled in 1 breath after fully inhaling

60
Q

How much is vital capacity?

A

4.8 litres

61
Q

What is inspiratory capacity?

A

The total amount of air that can be inspired in 1 breath

62
Q

How much is inspiratory capacity?

A

3.6 litres

63
Q

What is the functional residual capacity?

A

The amount of air remaining in the lungs after normal expiration

64
Q

How much is functional residual capacity?

A

2.4 litres

65
Q

What is pulmonary ventilation?

A

Total air movement into/out of lungs

66
Q

What is alveolar ventilation?

A

Fresh air getting into the alveoli available for gas exchange

67
Q

What is partial pressure?

A

The pressure of one particular gas in a mixture of gases

68
Q

How is partial pressure calculated?

A

Percentage of that particular gas in the mixture multiplied by the pressure of the entire mixture

69
Q

What is atmospheric pressure?

A

760mmHg, 101kPa

70
Q

Under normal conditions, what are the partial pressures of O2 and CO2?

A 
PO2= 100mmHg
PCO2= 35mmHg
71
Q

What is surfactant?

A

Detergent type liquid produced by type 2 pneumocytes

72
Q

What is the function of surfactant?

A

Reduce surface tension on alveolar surface to prevent alveolar collapse, particularly in smaller alveoli

73
Q

How does surfactant work?

A

Sits between water molecules on the alveolar surface and reduces attraction between them, therefore reducing the inward pressure that would cause alveoli to collapse

74
Q

How is pressure inside alveoli calculated?

A

2(surface tension) x radius of sphere

75
Q

When in gestation is surfactant produced?

A

25-36 weeks

76
Q

What stimulates surfactant production?

A

Thyroid hormones and cotisol

77
Q

What is compliance?

A

The change in lung volume relative to the change in pressure

78
Q

What does compliance represent?

A

The stretchability of the lungs

79
Q

What is high compliance?

A

Large increase in volume for small increase in pressure- little effort required

80
Q

What is low compliance?

A

Small increase in volume for a large decrease in intrapleural pressure

81
Q

What does high/low compliance indicate?

A

High- doesn’t necessarily indicate healthy lungs e.g. emphysema
Low- never healthy e.g. fibrosis

82
Q

How can the pressure changes of inspiration and expiration be compared?

A

It requires a greater change in pressure to reach a particular lung volume in inspiration than maintain it in expiration

83
Q

Where in the lung is compliance greatest?

A

Base

84
Q

Where in the lung is compliance least?

A

Apex

85
Q

Why is compliance greater at the base than the apex of the lung?

A

Alveoli at the base of the lung are ‘squashed’ more at the end of expiration and therefore have a greater range of inflation

86
Q

What happens in an obstructive lung disease?

A

Obstruction of airflow, particularly on expiration

87
Q

What happens in a restrictive lung disease?

A

Restriction of lung expansion

88
Q

What is a normal FEV1/FVC?

A

80%

89
Q

What is FEV1/FVC in obstructive and restrictive lung diseases?

A 
Obstructive= low %
Restrictive= normal-high %
90
Q

What is bronchial circulation?

A

Circulation supplying oxygenated blood to the bronchial smooth muscle, nerves and ling tissue

91
Q

What is pulmonary circulation?

A

Carries deoxygenated blood to the lungs for oxygenation

92
Q

What is the rate of diffusion across the membrane affected by?

A

Directly proportional to the partial pressure gradient, gas solubility and available surface area
Inversely proportional to the thickness of the membrane

93
Q

How does emphysema affect gas exchange?

A

Destruction of alveoli reduces surface area for gas exchange

94
Q

How does fibrotic lung disease affect gas exchange?

A

Thickened alveolar membrane slows gas exchange

95
Q

How does pulmonary oedema affect gas exchange?

A

Fluid in interstitial space increases diffusion distance and slows gas exchange

96
Q

What is the distribution of blood flow across the lung?

A

Declines with height across the lung

97
Q

Why is blood flow high at the base of the lung?

A

Arterial pressure is higher than alveolar pressure, decreasing vascular resistance

98
Q

Why is blood flow lower at the apex of the lung?

A

Alveolar pressure is greater than arterial pressure, increasing vascular resistance

99
Q

Where are ventilation and perfusion at their greatest?

A

At the base of the lung

100
Q

What is the V/Q ratio like at the base of the lung?

A

Low

101
Q

What is the V/Q ratio like at the apex of the lung?

A

High

102
Q

What is alveolar dead space?

A

Alveoli that are ventilated but not perfused

103
Q

What is anatomical dead space?

A

Air in the conducting zone of the respiratory tract unavailable for gas exchange

104
Q

What is physiological dead space?

A

Alveolar and anatomical dead space

105
Q

What is used to transport oxygen in the blood?

A

Haemoglobin

106
Q

How is the bulk of CO2 transported in the blood?

A

In solution in the plasma

107
Q

What does partial pressure of arterial O2 refer to?

A

The O2 in solution

108
Q

What is the partial pressure of arterial O2 determined by?

A

O2 solubility and the partial pressure of O2 in the gaseous phase

109
Q

What is normal PaO2?

A

100mmHg

110
Q

What is the O2 demand of tissues at rest?

A

250ml/min

111
Q

How much oxygen binds to 1g of haemoglobin?

A

1.34ml

112
Q

What is O2 saturation of haemoglobin at 100mmHg?

A

98%

113
Q

What types of haemoglobin have a higher oxygen affinity?

A

Foetal Hb and myoglobin

114
Q

What is anaemia?

A

Any condition where the oxygen carrying capacity of blood is compromised

115
Q

What can cause anaemia?

A

Iron deficiency
Haemorrhage
Vitamin B12 deficiency

116
Q

What factors affect the oxygen dissociation curve?

A

pH
PCO2
Temperature

117
Q

What effect does pH have on the oxygen dissociation curve?

A

Decrease- decreases affinity of Hb for O2

Increase- Increases affinity of Hb for O2

118
Q

What effect does PCO2 have on the oxygen dissociation curve?

A

Decrease- increases affinity of Hb for O2

Increase- decreases affinity of Hb for O2

119
Q

What effect does temperature have on the oxygen dissociation curve?

A

Decrease- increases affinity of Hb for O2

Increase- decreases affinity of Hb for O2

120
Q

What effect does CO have on oxygen binding to Hb?

A

CO has a higher affinity for Hb and prevents O2 from binding

121
Q

What are the symptoms of CO poisoning?

A

Hypoxia and anaemia
Nausea and headaches
Cherry red skin and mucous membranes

122
Q

What are the 5 main types of hypoxia?

A 
Hypoxic
Anaemic
Ischaemic
Histotoxic
Metabolic
123
Q

What is hypoxic hypoxia?

A

Reduction in O2 diffusion at lungs due to decreases atmospheric PO2 or tissue pathology

124
Q

What is anaemic hypoxia?

A

Reduction of O2 carrying capacity of blood due to anaemia

125
Q

What is ischaemic hypoxia?

A

Heart disease, resulting in inefficient pumping of blood to the lungs and around the body

126
Q

What is histotoxic hypoxia?

A

Poisoning prevents cells utilising oxygen delivered to them

127
Q

What is metabolic hypoxia?

A

Oxygen delivered to tissues does not meet increased oxygen demand by cells

128
Q

By what 3 methods is CO2 transported in the blood?

A

7% dissolved in plasma
23% combines with deoxyhaemoglobin to form carbamino compunds
70% combines with erythrocytes and water to form carbonic acid, which dissociates to give bicarbonate and H+

129
Q

What is the chloride shift?

A

Movement of bicarbonate out of the blood stream and Cl- ions into it

130
Q

What nerve innervates the diaphragm?

A

Phrenic nerve

131
Q

What nerve innervates the external intercostals?

A

Intercostal nerves

132
Q

What areas of the brain control breathing?

A

PONS and medulla

133
Q

What spinal level controls the diaphragm?

A

C3-5

134
Q

What does the dorsal respiratory root control?

A

Inspiration

135
Q

What does the ventral respiratory root control?

A

Expiration and maintain muscle tone in the pharynx, larynx and tongue

136
Q

What is the primary ventilatory drive?

A

Medulla

137
Q

What signal does the medulla respond to?

A

H+ ions (indirectly CO2)

138
Q

What do the central chemoreceptors respond to?

A

CSF H+ concentration

139
Q

Why do central chemoreceptors not respond to plasma H+?

A

The blood brain barrier is permeable to gases, not ions

140
Q

What do the peripheral chemoreceptors respond to?

A

Plasma H+ and PO2

141
Q

Where are the peripheral chemoreceptors located?

A

Carotid and aortic bodies

142
Q

What must PO2 fall below to activate the peripheral chemoreceptors?

A

60mmHg

143
Q

What does an decrease in blood pH cause?

A

Increased ventilation

144
Q

What drugs affect respiratory centres?

A

Barbituates and opioids depress respiratory centres
Gaseous anaesthetics increase respiratory rate but decrease tidal volume and alveolar ventilation
Nitrous oxide blunts peripheral chemoreceptor response

Respiratory AM (10 decks)

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