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Systems 1a Revision Decks > Resp. Physiology > Flashcards

Resp. Physiology Flashcards

1
Q

List the four functions of the respiratory system

A
  • Gas exchange
  • Protection from infection
  • Acid-base balance
  • Communication
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2
Q

What is external respiration?

A

Respiratory system coupled with cardiovascular system - oxygenation of blood and delivery to tissues

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3
Q

Describe the pulmonary circulation

A

Movement of blood from one side of the heart to the other via the lungs for the purpose of gas exchange

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4
Q

What vessels are important in pulmonary circulation?

A

Pulmonary arteries and vein

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5
Q

What is systemic circulation?

A

Movement of blood between heart and body

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6
Q

Describe the concurrent changes that occur in both the respiratory and cardiovascular system during exercise

A

Increased rate and depth of breathing occurs to speed up substrate acquisition and waste excretion

Heart rate and strength of contraction increases to increase substrate delivery and waste removal

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7
Q

Where does gas exchange occur?

A

In the lungs

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8
Q

What can be said about the net volume of oxygen exchanged in a steady state?

A

Its equal to the amount expended by the body’s cells

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9
Q

What are the average volumes of O2 and CO2 exchanged per minute?

A

250ml Oxygen

200ml Carbon dioxide

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10
Q

Describe the effect exercise has on breathing rate and quote numbers

A

10-20 breaths per minute at rest which increases to 40-45 breaths per minute during exercise

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11
Q

What is the epiglottis?

A

A small flap of tissue that covers the trachea when swallowing to prevent food from entering

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12
Q

What is the pharynx?

A

Shared space ‘throat’ between the respiratory and alimentary systems

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13
Q

What is the larynx?

A

The voice box, contains vocal chords which vibrate to produce sound

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14
Q

Where does the upper respiratory tract become the lower one?

A

T4

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15
Q

The width and angle of the right bronchi is greater and more oblique than the left one - what is the clinical relevance to this?

A

Most aspirated foreign bodies are lodged there

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16
Q

Describe the connective tissue surrounding the trachea and bronchi

A

Rings of cartilage ‘patency’ maintain semi-rigid tubes

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17
Q

Airways are categorised into two zones; what are they?

A

Conducting and respiratory zones

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18
Q

What do the tubes of the conducting zone contain?

A

Anatomical dead space - no gas exchange occurs

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19
Q

What are the components of the lining of the respiratory tract?

A

Epithelium, glands, lymph nodes, blood vessels, cilia and mucous

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20
Q

What is the function of mucous?

A

Trap pathogens and to moisten air

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21
Q

What are the two categories of pneumocytes?

A

Type 1 - Gas transfer

Type 2 - Surfactant releasing

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22
Q

What is the typical distribution of the types of pneumocytes?

A

97% type 1

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23
Q

Describe the lobular nature of the lungs

A

Right lung - three lobes

Left lung - two lobes (cardiac notch makes it smaller)

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24
Q

What does the horizontal fissure separate?

A

The superior and middle lobe of the right lung

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25
Q

What does the oblique lung fissure separate?

A

Middle lobe from inferior lobe in right lung

Superior from inferior lobe in left lung

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26
Q

What are the four Gas Laws and outline Boyle’s Law

A

Boyle’s Law - the relationship between the pressure of a gas an the volume of the system is directly inverse

Other laws include daltons law, Henrys law and Charles’ law

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27
Q

Describe the visceral pleural membrane?

A

Coats the inner surface of the lung

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28
Q

Describe the parietal pleural membrane?

A

Coats the outer surface of the lungs

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29
Q

What exists between the two pleura? What is its function?

A

Pleural fluid, sticks the lungs to the rib cage

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30
Q

What is pleurisy?

A

Inflammation of the pleura

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31
Q

What are the three relevant pressures in the lungs?

A
  • Intra-thoracic (Alveolar) pressure - (Pa)
  • Intra-pleural pressure (Pip)
  • Transpulmonary pressure (Pt)
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32
Q

Describe intra-thoracic pressure?

A

Pressure inside the thoracic cavity (essentially pressure inside the lungs) - may be both negative or positive compared to atmospheric pressure

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33
Q

Describe intra-pleural pressure

A

Pressure inside the pleural cavity - always negative

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34
Q

Describe transpulmonary pressure

A

Pressure differential between the alveolar and intra-pleural pressure - always positive

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35
Q

What is the definition of anatomical dead space?

A

Approx. 150ml of air in the conducting airways and not available for gas transfer

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36
Q

What is the definition of TV?

A

Tidal volume - the average volume of air on each inhalation/expiration on rest

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37
Q

What is the definition of ERV?

A

Expiratory reserve volume - the maximum volume of air expelled from the lungs at the end of a normal expiration

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38
Q

What is the definition of IRV?

A

Inspiratory reserve volume - the maximum amount of air that can be drawn into the lungs at the end of a normal inspiration

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39
Q

What is the definition of RV?

A

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

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40
Q

What is the definition of VC?

A

Vital capacity -

TV + IRV + ERV

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41
Q

What is the definition of TLC?

A

Total Lung Capacity -

Vital capacity + residual volume

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42
Q

What is the definition of IC?

A

Inspiratory capacity

Tidal volume + inspiratory reserve volume

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43
Q

What is the definition of FRC?

A

Forced Residual Capacity

Expiratory reserve volume + residual volume

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44
Q

What is the definition of FEV1?

A

Forced expiratory volume in one second

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45
Q

What is the definition of FEV1:FVC?

A

Fraction of forced vital capacity expelled in one second

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46
Q

What is pulmonary (minute) ventilation?

A

The amount of air breathed in and out during one minute

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47
Q

What is alveolar ventilation?

A

Fresh air getting to the alveoli and therefore available for gas exchange

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48
Q

What is the typical tidal volume?

A

500ml

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49
Q

What is the typical inspiratory reserve volume?

A

3L

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50
Q

What is the typical expiratory reserve volume?

A

1.1L

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51
Q

What is the typical reserve volume?

A

1.2L

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52
Q

What is the typical vital capacity?

A

4.6L

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53
Q

How is alveolar ventilation measured?

A

Tidal volume -Anatomical dead space (150ml) multiplied by breath rate

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54
Q

What is the typical alveolar ventilation?

A

4.2L.min^-1

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55
Q

How is partial pressure determined?

A

Dalton’s Law tells us partial pressure is equal to the percentage of the given gas as a proportion of total atmospheric pressure

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56
Q

What is surfactant?

A

Detergent like fluid secreted by type II pneumocytes

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57
Q

What is the function of surfactant?

A

To reduce the surface tension on alveolar surface membranes and therefore reduce its tendency to collapse

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58
Q

What is surface tension?

A

A phenomenon that occurs at air-water interfaces and refers to the attraction between water molecules

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59
Q

What is the overall effect of surfactant on the compliance of the lung

A

Increases

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60
Q

What is the Law of LaPlace?

A

Shows the relationship between pressure and a equation of surface tension and radius of the alveoli

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61
Q

What is the equation of the law of LaPlace?

A

P=2T/r

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62
Q

How does the law of LaPlace marry the different pressures in differently sized alveoli and what role does surfactant play?

A

Smaller alveoli have higher pressures, surfactant reduces surface tension and the pressure is equalised

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63
Q

What are the gestational milestone for surfactant production?

A

25 week - begins

Complete at 36

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64
Q

What hormone stimulates surfactant production in foetuses?

A

Thyroid and cortisol

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65
Q

When babies are born prematurely what pathology can rise to do with incomplete surfactant development

A

Infant respiratory distress syndrome

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66
Q

What is compliance?

A

A measure of the change in volume relative to the pressure change

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67
Q

What is meant by high compliance?

A

Large increase in volume for a small decrease in pressure

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68
Q

What is meant by low compliance?

A

Small increase in volume for a large increase in pressure

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69
Q

Describe the pressure-volume relationship

A

It requires a greater change in pressure to reach a particular volume because the word done during inspiration is recovered in elastic recoil for expiration

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70
Q

Describe the pressure-volume relationship associated with emphysema

A

Loss of elastic tissue means expiration requires effort

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71
Q

Describe the pressure volume relationship associated with fibrosis

A

Inert fibrous tissue means effort of inspiration increases

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72
Q

How does pressure volume curve vary in different regions of the lung/

A

At the base, the volume change is greater than the apex for a given change in pressure

Alveolar ventilation and compliance also decrease from apex to base

73
Q

Why is the volume change at the base of the lung greater than the apex for a given change in pressure?

A

At the base, alveoli are more compressed by the rest of the lung and the diaphragm therefore are more compliant on respiration

74
Q

What is the difference between obstructive and restrictive lung diseases?

A

Obstructive - obstruction of airways, particularly on expiration

Restrictive - restriction of lung expansion (inspiration)

75
Q

What are two examples of obstructive lung diseases?

A

Asthma and COPD (a combination of chronic bronchitis and emphysema)

76
Q

What are three examples of restrictive lung diseases/disorders?

A

IRDS
Oedema
Pneumothorax

77
Q

What is spirometry?

A

A technique used to measure lung function. Measurements can either be classes as static or dynamic

78
Q

What is the difference between static and dynamic measurements in spirometry?

A

Static - where the only consideration made is volume exhaled

Dynamic - where the time taken to exhale a certain volume is being measured

79
Q

What lung volumes and capacities can’t be directly measured by spirometry?

A

RV, TLC and FRC

80
Q

What is a typical FEV1 value for healthy males?

A

4L

81
Q

What is a typical FVC in healthy males?

A

5L

82
Q

What is the typical FEV1/FVC for a healthy male as a percentage?

A

80%

83
Q

What FEV1/FVC percentage is typically seen in obstructive pulmonary disease?

A

<80%

84
Q

What FEV1/FVC percentage is typically seen in restrictive lung diseases?

A

> 80%

85
Q

Why are obstructive diseases characterised by an FEV1/FVC percentage <80%?

A

Rate at which air is exhaled is slower; reduced FEV1 and little effect on FVC therefore ration is reduced

86
Q

Why are restrictive diseases characterised by an FEV1/FVC percentage >80%?

A

Total lung volume is reduced therefore ratio can increase as a large proportion of volume can still be expelled quickly

87
Q

What are the limitations for the FEV1/FVC for both types of respiratory disorder?

A

Both FEV and FVC fall - the ratio will stay the same despite seriously compromised function

88
Q

What FEF25-75?

A

Forced expiratory flow - average expired flow over the middle half of the FVC

89
Q

What is the advantage of using FEF25-75?

A

Correlates with FEV1 but changes are generally more striking

90
Q

What is the disadvantages of using FEF25-75?

A

‘Normal’ range is greater

91
Q

What vessels supply the bronchial circulation?

A

Bronchial arteries

92
Q

What circulatory system gives rise to the bronchial circulation?

A

Systemic

93
Q

What is the function of the bronchial circulation?

A

Supplies airway smooth muscle, nerves and lung tissue with oxygen

94
Q

Why is the pulmonary circulation referred to as high flow, low pressure?

A

High flow - entire cardiac output 5L/min flows through it

Low pressure - only has systolic pressure of 25mmHg

95
Q

What force influences a low pressure circulatory system?

A

Gravity

96
Q

Expand on the following abbreviations:

a
A
v
P

A

a - arteriolar
A - alveolar
v - venous
P - partial pressure

97
Q

Therefore what does PaCO2 refer to?

A

Partial pressure of carbon dioxide in the arteries

98
Q

What is the partial pressure of oxygen in the alveoli and arteries?

A

100mmHg or 13.3 kPa

99
Q

What is the partial pressure of carbon dioxide in the alveoli and arteries?

A

40mmHg or 5.3 kPa

100
Q

What is the partial pressure of venous oxygen?

A

40mmHg or 5.3kPa

101
Q

What is the partial pressure of venous carbon dioxide?

A

46mmHg or 5.6kPa

102
Q

What four factors effect the rate of gas exchange?

A
  • Partial pressure gradient
  • Gas solubility
  • Surface area
  • Membrane thickness
103
Q

What partial pressure values reflect gas concentrations in the lungs?

A

Arteriolar pp

104
Q

What partial pressure values reflect gas concentrations in the tissues?

A

Venous pp

105
Q

How does fibrotic alveolar membrane decrease rate of gas exchange?

A

Thickened membrane

106
Q

How does pulmonary oedema decrease rate of gas exchange?

A

Increased diffusion distance through fluid

107
Q

How does asthma reduce gas transfer?

A

Constricted bronchi increase resistance to ventilation

108
Q

What is ventilation?

A

Air getting into the alveoli

109
Q

What is perfusion?

A

Local blood flow

110
Q

What is the optimal condition for ventilation and perfusion?

A

They are equal

111
Q

What two forces influence distribution of blood flow?

A

Hydrostatic blood pressure and alveolar pressure

112
Q

What is blood flow in the lungs proportional to?

A

Vascular resistance

113
Q

What trend does blood flow demonstrate in relation to height of the lung?

A

Decreases with height

114
Q

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

A

Arterial pressure > alveolar pressure

Therefore vascular resistance is low

115
Q

A decrease in PAO2 in the alveoli causes what to occur?

A

Shunt of blood to more well ventilated alveoli

116
Q

What does an increase in PACO2 do?

A

Causes mild bronchodilation

117
Q

What respond to hypoxia is unique to the pulmonary system?

A

Constriction

118
Q

What is shunting?

A

Refers to the physiological changes that occur in poorly ventilated areas of the lung

119
Q

What is alveolar dead space?

A

Alveoli the are well ventilated but poorly perfused

120
Q

What volume of oxygen is transported in solution in the plasma?

A

3ml

121
Q

The presence of haemoglobin increases the carrying capacity of oxygen to what value?

A

250ml/L

122
Q

How is the bulk of CO2 carried in the blood?

A

Various forms of solution in plasma and RBC

123
Q

What is the O2 demand of resting tissue?

A

250ml/min

124
Q

What percentage of arterial O2 is extracted by peripheral tissues at rest?

A

25%

125
Q

What form of haemoglobin makes up 92% of all types found in an RBC?

A

HbA

126
Q

Describe the composition of the 8% of other haemoglobin types

A

HbA2 (delta chain replaces beta)

Glcosylaed Hb (HbA1, HbA1b and HbA1c)

127
Q

What factor is the major determinant of the degree to which Hb is saturated with oxygen?

A

Partial pressure of oxygen

128
Q

How long does it take to saturate and Hb molecule with oxygen? How does this compare to its overall exposure time?

A

0.25 seconds to saturate

Overall exposure is 0.75 seconds

129
Q

List three factors which decrease haemoglobin oxygen affinity

A

Heat
PCO2 increase
Decreased pH

130
Q

Where can the conditions that lead to a decreased oxygen affinity exist?

A

Locally in actively metabolising tissues (e.g. muscles) which helps to unload oxygen

131
Q

What conditions cause a rise in haemoglobin oxygen affinity?

A

Increase in pH
Fall in PCO2
Drop in temp.

132
Q

What molecule can cause haemoglobin oxygen affinity to decreased?

A

2,3-diphosphoglycerate (2,3-DPG)

133
Q

Where is 2,3-DPG synthesised?

A

RBCs

134
Q

Where does 2,3-DPG activity increase?

A

Associated with areas of inadequate oxygen supply e.g. heart or lung disease and living at high altitude

135
Q

What is the overall effect of 2,3-DPG?

A

Helps maintain oxygen release

136
Q

What occurs to haemoglobin in the presence of carbon monoxide?

A

Forms carboxyhemoglobin

137
Q

What is the partial pressure of CO required to cause progressive carboxyhemoglobin formation?

A

0.4mmHg

138
Q

Why is the respiration rate of a person suffering with CO poisoning normal?

A

PaCO2 not effected

139
Q

What are the five main types of hypoxia?

A 
Hypoxic 
Ischaemic 
Histotoxic 
Metabolic 
Anaemic
140
Q

What is the most common type of hypoxia?

A

Hypoxic

141
Q

What is the cause of anaemic hypoxia?

A

Reduction in O2 carrying capacity due to anaemia

142
Q

What is ischaemic hypoxia?

A

Heart disease results in poor pumping of the blood

143
Q

What is histotoxic hypoxia?

A

Poisoning prevents cells using oxygen

144
Q

Give an example of a cause of histotoxic hypoxia

A

CO or cyanide

145
Q

What is metabolic hypoxia?

A

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

146
Q

What proportion of CO2 remains dissolved in plasma and RBCs?

A

7%

147
Q

23% of CO2 combines with deoxyhaemoglobin to form what compounds?

A

Carbamino compounds

148
Q

What is the compound which sequesters most of the CO2 excreted by cells?

A

70% converted to carbonic acid

149
Q

Describe the fate of carbonic acid in the blood

A

Dissociates into hydrogen and bicarbonate ions - the bicarbonate is transported into the plasma by the Hamburger Phenomenon and forms a blood buffer

150
Q

Why is monitoring plasma [CO2] very important?

A

It is capable of changing the ECF pH

151
Q

What physiological process monitors plasma [CO2]?

A

Hypo/hyperventilation

152
Q

How does hypoventilation alter plasma [CO2]?

A

Retains CO2

153
Q

How does hyperrventilation alter plasma [CO2]?

A

Blows off CO2

154
Q

What physical structures must be stimulated to cause inspiration?

A

Diaphragm and external intercostals

155
Q

What innervates the thoracic-abdominal diaphragm?

A

The phrenic nerve

156
Q

Which nerves innervate the external intercostals?

A

Intercostal nerves

157
Q

Where are the respiratory centres located in the brain?

A

The pons and medulla

158
Q

What can be said about the voluntary/involuntary nature of breathing?

A

Its mostly subconscious but can be subject to voluntary override

159
Q

Severing of the spinal chord above the ventral rami of spinal nerves C3, 4 and 5 do what?

A

Kill you

160
Q

How does the dorsal respiratory group set the rhythm for breathing?

A

Firing smooth repetitive bursts of action potentials

161
Q

What four other aspects can modulate ventilation?

A
  • Emotion
  • Voluntary override
  • Mechano-sensory input from the thorax
  • Chemical changes
162
Q

What two types of chemoreceptors modulate ventilation?

A

Central and peripheral

163
Q

What chemical route, central or peripheral, is the main control for ventilatory function?

A

Central

164
Q

Central chemoreceptors respond directly to what?

A

[H+] in cerebrospinal fluid

165
Q

What does the [H+] indicate?

A

PaCO2

166
Q

Where are central chemoreceptors located?

A

Medulla of the brain

167
Q

Where are peripheral chemoreceptors located in the body?

A

Carotid and aortic bodies

168
Q

What do peripheral chemoreceptors detect?

A

Changes in arterial PO2 and [H+]

169
Q

Changes in plasma pH will alter ventilation via what chemoreceptor pathway?

A

Peripheral

170
Q

If plasma pH falls ventilation will be _______

A

Increased

171
Q

If plasma pH increases, ventilation will be _____

A

Inhibited

172
Q

List common drugs which depress respiratory activity

A

Opiates, barbiturates

173
Q

What effect do most anaesthetic agents have on respiratory activity

A

Increase breath rate but decrease tidal volume therefore decrease alveolar ventilation

174
Q

What effect does nitrous oxide have on the nervous system?

A

Blunts the peripheral chemoreceptors to changes in PO2

175
Q

In what kind of patient would the use of nitrous oxide be contraindicated?

A

Ones on hypoxic drive

176
Q

What is hypoxic drive?

A

The body regulating its respiratory activity by monitoring PO2 not PCO2

177
Q

What common treatment for lung diseases would aggravate a patient on hypoxic drive?

A

Oxygen

178
Q

Describe the relationship between ventilation and swallowing

A

Swallowing causes the epiglottis to close and is followed by a reflex exhalation to prevent food from being aspirated

Systems 1a Revision Decks (22 decks)

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