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Respiratory System > Respiratory Physiology > Flashcards

Respiratory Physiology Flashcards

1
Q

Functions of the respiratory system

A

Gas exchange
Acid base balance
Protection from infection
Communication via speech

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2
Q

Main factors affection blood oxygen levels

A

Composition of inspired air
Alveolar ventialtion
Oxygen diffusion between alveoli and blood
Adequate perfusion of alveoli

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3
Q

Blood transport of pulmonary artery

A

Away from heart

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4
Q

Blood transport of pulmonary vein

A

Towards heart

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5
Q

Net volume of gas exchanged in the lungs

A

250ml/min oxygen, 200ml/min carbon dioxide

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6
Q

Respiration rate at rest

A

12-18 breaths/min, 40-45 at max.

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7
Q

Respiratory system pathway

A

Nose, pharynx, epiglottis, larynx, trachea, bronchus, bronchiole, alveoli

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8
Q

Function of nose

A

Warms and moistens air coming in

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9
Q

Function of epiglottis

A

Flap over trachea that prevent food entering

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10
Q

Function of larynx

A

Voice box that contains vocal chords

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11
Q

Division between upper and lower respiratory tract

A

Larynx which is the final structure of upper respiratory tract

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12
Q

Structure that maintains the patency of trachea and bronchi

A

C-shaped rings of cartilage

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13
Q

Impact of decreasing diameter of airway on airflow resistance

A

Airflow resistance increases. (vv)

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14
Q

Alveoli cells

A

Type I and II alveolar cells (pneumocytes) and macrophages

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15
Q

Function of type I alveolar cells

A

Gas exchange

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16
Q

Function of type II alveolar cells

A

Secrete surfactant

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17
Q

Function of elastic fibres of alveoli

A

Stretch during inspiration and coil to squeeze out air during expiration

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18
Q

Anatomical dead space

A

Gas in the upper airways that does not participate in gas exchange (150ml)

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19
Q

Functions of mucous

A

Moistens air
Traps particles
Provides large surface area for cilia to act on

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20
Q

Boyle’s gas law

A

States that the pressure exerted by a gas is inversely proportional to its volume

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21
Q

Number of and names of lobes of right lung

A

3 lobes

Superior, middle and inferior

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22
Q

Number of and names of lobes of left lung

A

2 lobes

Superior and inferior

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23
Q

Pleaural sac components

A

Visceral pleaural membrane, parietal pleural membrane and pleaural fluid

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24
Q

Visceral pleural membrane

A

Coats outer surface od the lungs

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25
Q

Pariteal pleaural membrane

A

Coats inner surface of the ribs

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26
Q

Pleaural fluid

A

(5ml)
Allows membranes to glide across each other and reduces friction.
Stops membranes separating so that the lungs are stuck to the rib cage and diaphragm.

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27
Q

Muscles of inspiration

A

External intercostal muscles, diaphragm, scalene and sternocleidomastoids.

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28
Q

Muscles of expiration

A

Internal intercostal muscles and abdominal muscles

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29
Q

Movement of gas

A

From high pressure to low pressure

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30
Q

Diaphragm during inspiration

A

Contacts so that thoracic volume increases

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31
Q

Diaphragm during expiration

A

Relaxes so that thoracic volume decrease.

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32
Q

Pump handle motion of intercostals

A

Increases anterior-posterior dimension of rib cage

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33
Q

Bucket handle motion of intercostals

A

Increases lateral dimension of rib cage.

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34
Q

Asthma

A

Over-reactive constriction of bronchial smooth muscles, increase airway resistance

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35
Q

Intra-thoracic (alveolar) pressure

A

Pressure inside the thoracic cavity. Negative or positive relative to atmospheric pressure

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36
Q

Intra-pleaural pressure

A

Pressure inside pleural cavity. Always negative relative to atmospheric pressure. Created by opposing pulls.

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37
Q

Transpulmonary pressure

A

Difference between alveolar and intra-pleural pressure. Always positive relative to atmospheric pressure

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38
Q

Changes of alveolar pressure relative to atmospheric pressure

A

Inspiration - negative

Expiration - positive

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39
Q

Changes of intra-pleural pressure relative to atmospheric pressure

A

Inspiration - more negative

Expiration - less negative

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40
Q

Tidal volume

A

The volume of air breathed out of lungs at each breath - 500ml

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41
Q

Expiratory reserve volume

A

The maximum volume of air which can be expelled from the lungs at the end of a normal expiration - 1100ml

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42
Q

Inspiratory reserve volume

A

The maximum volume of air which can be drawn into the lungs at the end of a normal inspiration - 3000ml

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43
Q

Residual volume

A

The volume of gas in the lungs at the end of a maximal expiration - 1200ml

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44
Q

Vital capacity

A

TV+IRV+ERV - 4600ml

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45
Q

Total lung capacity

A

VC+RV - 5800ml

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46
Q

Inspiratory capacity

A

TV+IRV - 3500ml

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47
Q

Functional residual capacity

A

ERV+RV - 2300ml

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48
Q

Ventilation

A

The movement of air in and out of lungs

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49
Q

Pulmonary ventilation

A

Total air movement in and out of lungs

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50
Q

Alveolar ventialtion

A

Fresh air getting to alveoli and so available for gas exchange

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51
Q

Volume of air participating in gas exchange at rest

A

350 out of 500ml due to anatomical dead space.

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52
Q

Factors effecting ventilation

A

Depth of breathing

Respiratory rate

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53
Q

Dalton’s law

A

States that the total pressure of a gas mixture is the sum of the pressure of the individual gases

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54
Q

Partial pressure

A

The percentage of individual gas in gas mixture multiplied by the total pressure

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55
Q

Normal alveolar pressure of oxygen

A

100mmHg (13.3kPa)

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56
Q

Normal alveolar pressure iof carbon dioxide

A

40mmHg (5.3kPa)

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57
Q

Surfactant

A

Detergent like fluid that reduced surface tension on alveolar surface membrane

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58
Q

Surface tension

A

Attraction of one water molecule to another

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59
Q

Effect of surfactant

A

Reduces tendency for alveoli to collapse
Increases lung compliance
Reduces lung’s tendency to recoil
Makes work of breathing easier

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60
Q

Reason surfactant more effective in small alveoli

A

Because surfactant molecules come closer together and are therefore more concentrated

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61
Q

Saline

A

Liquid which inflates lungs in utero - less change in pressure required as do not need to overcome surface tension

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62
Q

Compliance

A

Change in volume relative to change in pressure

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63
Q

High compliance

A

Large increase in lung volume for a small decrease in intra-pleural pressure

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64
Q

Low compliance

A

Small increase in lung volume for a large decrease in intra-pleural pressure.

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65
Q

Compliance during inspiration compared to expiration

A

Lower due to tissue inertia - starting stretch required to open up compressed airways

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66
Q

Compliance in emphysema

A

Reduced as loss of elastic tissue means expiration requires effort

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67
Q

Compliance in fibrosis

A

Reduced due to inert fibrous tissue increasing effort of inspiration

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68
Q

Effect of height of alveolar ventilation

A

Alveolar ventilation declines with height from base to apex

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69
Q

Effect of height on compliance

A

Compliance declines with height from base to apex

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70
Q

Obstructive lung disease

A

Obstruction of air flow through airways, especially on expiration

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71
Q

Restrictive lung disease

A

Restriction of lung expansion

72
Q

Examples of obstructive lung diseases

A

Asthma

COPD

73
Q

Examples of restrictive lung diseases

A

Fibrosis
Infant respiratory distress syndrome (insufficient surfactant production)
Oedema
Pneumothorax

74
Q

Spirometry

A

Technique commonly used to measure lung function

75
Q

Static spirometry

A

Only consideration made is the volume exhaled

76
Q

Dynamic spirometry

A

Time taken to exhale a certain volume is what is being measured

77
Q

Lung volumes that can be measured by spirometry

A

TV, IRV, ERV, IC, VC - if you can breathe it then spirometry can measure it

78
Q

FEV1

A

Forced expiratory rate in one second

79
Q

FVC

A

Forced vital capacity (breathing out as hard as you can)

80
Q

FEV1/FVC ratio in healthy individuals

81
Q

FEV1/FVC in obstructive lung disease

A

FEV1 reduces greatly
FVC reduces
Ratio decrease

82
Q

FEV1/FVC in restrictive lung disease

A

FEV1 reduces greatly
FVC reduces greatly
Ratio unchanged

83
Q

Forced expiratory flow

A

Average expired flow over the middle of an FVC, correlates with FEV1 but changed are generally more striking, ‘normal’ range is greater

84
Q

Bronchial circulation

A

Nutritive, from systemic circulation to supply oxygenated blood to airway smooth muscle, nerves and lung tissue

85
Q

Pulmonary circulation

A

Gas exchange, unique system, supplies dense capillary network surrounding alveoli and returns oxygenated blood.

86
Q

Blood flow in pulmonary circulation

A

High flow, low pressure

87
Q

What determines the partial pressure of gases in the alveoli

A

The partial pressure of gases in the arterial blood

88
Q

What determines the partial pressure of gases in the tissues

A

The partial pressure of gases in the venous blood

89
Q

PAo2

90
Q

PAco2

91
Q

Pao2

92
Q

Paco2

93
Q

Pvo2

94
Q

Pvco2

95
Q

Gas exchange at alveoli

A

Oxygen moves from alveoli to arterial blood and carbon dioxide moves from venous blood to alveoli.

96
Q

Gas exchange at tissues

A

Oxygen moves from arterial blood to tissues and carbon dioxide moves from tissues to venous blood.

97
Q

Gases moves between the alveoli, blood and tissue by

A

Diffusion, down their partial pressure gradient

98
Q

5 factors that effect diffusion rate

A

Directly proportional to the partial pressure gradient, gas solubility and available surface area. Inversely proportional to the thickness of membrane. More rapid over short distances.

99
Q

Why does carbon dioxide diffuse at the same pace as oxygen despite less volume of movement

A

Because carbon dioxide is more soluble in water than oxygen - equalises effect of greater pressure difference of oxygen

100
Q

Gas exchange in emphysema

A

Destruction of alveoli reduces surface area for gas exchange

101
Q

Gas exchange in fibrotic lung disease

A

Thickened alveolar membrane slows gas exchange

102
Q

Gas exchange in pulmonary oedema

A

Fluid in interstitial space increases diffusion distance. (CO2 may be normal due to high solubility in water)

103
Q

Gas exchange in asthma

A

Increased airway resistance decreases airway ventilation - no problem with diffusion.

104
Q

Ventilation-perfusion relationship at apex of lungs

A

Lower perfusion than ventilation

105
Q

Ventilation-perfusion relationship at base of lungs

A

Higher perfusion than ventilation

106
Q

Effect of height on perfusion

A

Perfusion decreases with height from base to apex

107
Q

Effect of decreased ventilation in alveoli

A

Pco2 increases and Po2 decreases - blood flowing past is not oxygenated, shunt

108
Q

Control mechanism in response to decrease in ventilation

A

Constriction of arterioles around under ventilated alveoli, blood flow redirected to better ventilated alveoli

109
Q

Effect of decreased perfusion

A

Alveolar dead space, Po2 increases and Pco2 decreases

110
Q

Control mechanism in response to decrease in perfusion

A

Pulmonary vasodilation to increase perfusion and mild bronchial constriction to decrease ventilation

111
Q

Shunt

A

The passage of blood through areas of the lung that are poorly ventilated, opposite of alveolar dead space

112
Q

Alveolar dead space

A

Alveoli that are ventilated but not perfused

113
Q

Physiological dead space

A

Alveolar dead space + anatomical dead space

114
Q

How much oxygen per litre dissolves in the plasma

115
Q

Haemoglobin increase oxygen carrying capacity to

116
Q

Arterial pressure oxygen defined as

A

The oxygen in solution in the plasma

117
Q

The partial pressure of oxygen in determined by

A

Oxygen solubility and the partial pressure of oxygen in the gaseous phase that is driving oxygen into solution

118
Q

Oxygen demand of resting tissues

119
Q

Actual oxygen delivery to tissues

A

1000ml/min

120
Q

Percentage of arterial oxygen extracted by peripheral tissues at rest

A

25% resulting in a 75% reservoir

121
Q

Structure of haemoglobin

A

4 polypeptide chains (2 alpha, 2 beta) each associated with an iron containing ham group

122
Q

Amount of oxygen that binds to each gram of haemoglobin

123
Q

Oxygen binds to haemoglobin by

A

Oxygenation (not oxidation)

124
Q

Percentage of haemoglobin in red blood cells is in the form HbA

125
Q

Other forms of haemoglobin

A

HbA2, HbF, glycosylated

126
Q

Major determinant of the degree to which haemoglobin is saturated with oxygen

A

Partial pressure of oxygen in arterial blood

127
Q

Haemoglobin saturation is complete after how much contact with alveoli

A

0.25 seconds

128
Q

Haemoglobin saturation at PaO2 100mmHg

129
Q

Haemoglobin saturation at PaO2 40mmHg

A

75% (still 75% reserve)

130
Q

Reason why HbF and myoglobin have a higher affinity for oxygen that HbA

A

Necessary for extracting oxygen from maternal/arterial blood

131
Q

Anaemia

A

Any condition where the oxygen carrying capacity of the blood is compromised

132
Q

Examples of anaemia

A

Iron deficiency, haemorrhage, vitamin B12 deficiency

133
Q

Effect of anaemia on PaO2

134
Q

Effect of anaemia on haemoglobin oxygen saturation

135
Q

Factors that effect the affinity of haemoglobin for oxygen

A

pH, Pco2, temperature and 2,3-DPG

136
Q

Affinity of haemoglobin for oxygen decreased by

A

Decrease in pH, increase in Pco2, increase in temperature, binding of 2,3-DPG

137
Q

Affinity of haemoglobin for oxygen increased by

A

Increase in pH, decrease in Pco2, decrease in temperature, no 2,3-DPG

138
Q

2,3-diphosphoglycerate (2.3-DPG) is synthesised by

A

Erythrocytes

139
Q

When does 2,3-DPG increase and why

A

When there is inadequate oxygen supply (e.g. high altitudes) to maintain oxygen release in the tissues

140
Q

Affinity of haemoglobin for carbon monoxide compared to oxygen

A

250 times greater

141
Q

Problem of carbon monoxide

A

Binds to haemoglobin readily (carboxyhaemoglobin) and dissociates very slowly, prevents oxygen from binding to haemoglobin

142
Q

Hypoxaemic hypoxia

A

Reduction in oxygen diffusion at lungs

143
Q

Anaemic hypoxia

A

Reduction in oxygen carrying capacity of blood due to anaemia

144
Q

Stagnant hypoxia

A

Inefficient pumping of blood to lungs/around the body

145
Q

Histotoxic hypoxia

A

Poisoning prevent cells utilising oxygen delivered to them

146
Q

Metabolic hypoxia

A

Oxygen delivery to the tissues does not meet increased oxygen demand by cells

147
Q

Percentage of carbon dioxide that remains dissolved in plasma and erythrocytes

148
Q

Percentage of carbon dioxide that combines in erythrocytes with deoxyhemoglobin

149
Q

Product formed when carbon dioxide combines with deoxyhemoglobin

A

Carbamino compounds

150
Q

Percentage of carbon dioxide that combines in erythrocytes with water

151
Q

Product formed when carbon dioxide combines with water

A

Carbonic acid

152
Q

Fate of carbonic acid

A

Dissociates to yield bicarbonate and hydrogen ions

153
Q

Fate of bicarbonate

A

Moves out of erythrocytes into the plasma in exchange for chlorine ions

154
Q

Fate of excess hydrogen ions

A

Bind to deoxyhemoglobin

155
Q

Carbon dioxide is capable of changing ECF pH due to

A

Production of hydrogen ions when combined and dissociated

156
Q

Ventilatory control resides within

A

Respiratory centres - ill defined centres in the [os and medulla

157
Q

Ventilatory control in entirely depending on

A

Signalling from the brain (doesn’t have its own rhythmic beat)

158
Q

Respiratory centres function

A

Set an automatic rhythm for breathing and adjust thus rhythm in response to stimuli

159
Q

Respiratory centres set an automatic rhythm of breathing through

A

Co-ordinating the firing of smooth and repetitive bursts of action potentials to DRG

160
Q

Dorsal respiratory group (DRG)

A

Output primarily to inspiratory muscles

161
Q

Ventral respiratory group (VRG)

A

Output to expiratory muscles, some inspiratory, pharynx, larynx and tongue muscles

162
Q

Pontine respiratory group (PRG)

A

Contains higher brain centres

163
Q

Respiratory centres have their rhythm modulated by

A

Emotion, voluntary over-ride, mechano-sensory input from thorax, chemical composition of blood

164
Q

Chemical composition of blood is detected by

A

Chemoreceptors

165
Q

Central chemoreceptors

A

In medulla, respond directly to hydrogen ions, primary ventilation drive

166
Q

Peripheral chemoreceptors

A

Carotid and aortic bodies, respond primary to plasma hydrogen ion concentration and PO2, secondary ventilatory drive

167
Q

Hypercapnea

A

Raised Pco2

168
Q

Central chemoreceptors detect changes in hydrogen ion concentration in

A

Cerebral spinal fluid around brain

169
Q

Central chemoreceptors cause a reflex stimulation of ventilation following

A

A decrease in arterial Pco2

170
Q

What can and can’t pass blood brain barrier

A

Gas can (carbon dioxide), ions can’t (hydrogen ions)

171
Q

Effect of chronic lung disease on chemoreceptors

A

Pco2 is chronically elevated, central chemoreceptors become desensitised to Pco2, have to rely on peripheral chemoreceptors and changed in Po2 to stimulate ventilation - hypoxic drive

172
Q

Peripheral chemoreceptors cause a reflex stimulation of ventilation following

A

A significant fall in arterial Po2 or a rise in hydrogen ion concentration

173
Q

Peripheral chemoreceptors will only cause stimulation if oxygen partial pressure falls below

174
Q

Effect of fall of plasma pH on ventilation

A

Ventilation will be stimulated and vv

175
Q

Reason why respiration is inhibited during swallowing

A

To avoid aspiration of food or fluids into the airways

176
Q

Common drugs that affect respiratory centres

A

Barbiturates, opioids, gaseous anaesthetics, nitrous oxide

Respiratory System (20 decks)

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