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BMS242 CVS Phys > L1-4 Respiration > Flashcards

L1-4 Respiration Flashcards

1
Q

Describe the relationship between pressure gradient resistance and flow during laminar flow

A

Flow rate proportional to the pressure gradient and inversely proportional to the resistance

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2
Q

Equation for laminar flow

A

V = delta P / R

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3
Q

Equation for turbulent flow

A

V=k ROOT(delta P)

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4
Q

Three types of flow in the lungs

A

Laminar turbulent and transitional

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5
Q

Describe laminar flow

A

Steady flow down a tube with uniform direction and speed

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6
Q

During laminar flow, where is flow rate the highest

A

The centre

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7
Q

What are present in turbulent flow

A

Vorticies and eddie currents

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8
Q

A change in pressure gradient will have a greater effect on flow rate in laminar or turbulent

A

Laminar - turbulent flow requires a larger change in pressure gradient for the same effect to be seen on flow rate

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9
Q

Transitional flow arises as a result of

A

High number of biurification

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10
Q

Transitional flow is charaterised as

A

The switching between laminar and turbulent

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11
Q

What number is used to determine flow type

A

Reynolds

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12
Q

Give the equation for Reynolds number

A

Re = (2rvp)/n

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13
Q

In the Reynolds equations what does the following character represent: Re

A

Reynolds number

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14
Q

In the Reynolds equations what does the following character represent: r

A

Radius

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15
Q

In the Reynolds equations what does the following character represent: v

A

Velocity

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16
Q

In the Reynolds equations what does the following character represent: p

A

Density of the gas

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17
Q

In the Reynolds equations what does the following character represent: n

A

Viscosity

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18
Q

What type of flow if Re less than 1000

A

Laminar

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19
Q

What type of flow if Re greater than 1500

A

Turbulent

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20
Q

What type of flow if Re between 1000 & 1500

A

Transitional

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21
Q

In the lung a Re of around ___ is required for laminar flow

A

10

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22
Q

Why may a Re less than 1000 not give laminar flow in the lungs

A

Not uniform shapped tubes

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23
Q

Why does velocity initially increase in the lungs

A

Tube gets smaller - must increase velocity to maintain flow rate

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24
Q

At the top: High/low CSA

A

Low

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25
Q

At the bottom: High/low CSA

A

High

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26
Q

At the top: high/low velocity

A

High

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27
Q

At the bottom: High/low velocity

A

Low

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28
Q

At the top: laminar/turbulent

A

Turbulent

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29
Q

At the bottom: Laminar/turbulent

A

Laminar

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30
Q

What does Poiseulles law determine

A

Resistance

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31
Q

What is the key point of Poiseulles law?

A

That a small change in airway diameter will have a large effect in R

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32
Q

What is the relationship between radius and resistance

A

Inversely proprtional to the 4th root of the radius

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33
Q

Give Poiseuilles Law

A

R = (8/pi) X (nl/r^4)

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34
Q

In healthy lungs, what is the contribution of the following to total resistance: Pharynx and larynx

A

40%

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35
Q

In healthy lungs, what is the contribution of the following to total resistance: Airways with a diameter greater than 2mm

A

40%

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36
Q

In healthy lungs, what is the contribution of the following to total resistance: Airways with a diameter less than 2mm

A

20%

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37
Q

In COPD lungs, what is the contribution of the following to total resistance: Pharynx and larynx

A

12%

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38
Q

In COPD lungs, what is the contribution of the following to total resistance: Airways with a diameter greater than 2mm

A

18%

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39
Q

In COPD lungs, what is the contribution of the following to total resistance: Airways with a diameter less than 70%

A

70%

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40
Q

What is total resistance in healthy lungs

A

1.5 cm H20 s /L

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41
Q

What is total reistance in COPD lungs

A

5 cm H20 S /L

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42
Q

Why is resistance greater in the larger airways

A

Resistances in series, in later (smaller) airways the resistances are in parallel

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43
Q

How do resistances sum when in series

A

R = R1 + R2 + R3

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44
Q

How do resistances sum when in parallel

A

R = 1/R1 + 1/R2 + 1/R3

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45
Q

Two factors which may affect the diameter of the airway

A

Mucus secretions

Oedema

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46
Q

Pa

A

Alveolar pressure

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47
Q

Paw

A

Airway pressure

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48
Q

Pb

A

Barometric pressure

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49
Q

Pip

A

Intrapleural pressure

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50
Q

Ptm

A

Transmural pressure

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51
Q

Ptp

A

Transpulmonary pressure

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52
Q

Pip =

A

Pip = (-Ptp) + Pa

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53
Q

Ptm =

A

Ptm = Paw - Pip

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54
Q

Describe how airway compression occurs in emphysem

A

Tethering between adjoining airspaces is reduced, airways are flimsy, during a forced expiration the airways are less able to resist collapse

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55
Q

Characteristics of emphysema

A

Loss of elastic tissue and breakdown of the alveolar walls

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56
Q

What techniques may people suffering with emphysema use to prevent airway collapse

A

Slow exhalation
Breathing at a higher lung volume
Breathing through pursed lips

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57
Q

At any given volume airway _____ is higher for people suffering with COPD

A

Resistance

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58
Q

Define ventilation

A

Total ventilation is the volume of air moved out of the lungs per unit time

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59
Q

Equation for ventilation

A

V. = v/t (volume/time)

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60
Q

Normal tidal volume

A

0.5 L

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61
Q

Normal ventilation rate

A

12 per min

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62
Q

What is total ventilation at rest

A

61 L per min

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63
Q

What is another word for the conducting zone

A

Anantomical dead space

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64
Q

Because of the anatomical dead space, what does this mean for the amount of fresh air reaching the alveoli

A

Not all will reach the alveoli

First portion of air reaching the respiratory zone is the stale air that was in the conducting zone ~0.15L

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65
Q

Define alveolar ventilation

A

The volume of fresh air reaching the repsiratory zone

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66
Q

What is the formula for alveolar ventilation

A

Total ventilation - dead space ventilatio

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67
Q

Normal value for alveolar repsiraition

A

6 - (0.15 x 12)

=4.2 L/min

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68
Q

Ventilation rate has an effect on _________ and ___________ gas compositions

A

Alveolar and aterial

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69
Q

At low alveolar ventilation ….

A

200 ml CO2 produced, less air to dilute it so greater p CO2

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70
Q

At a higher alveolar ventilation …

A

200 ml CO2 produced, more air for it to dilute into, so lower PCo2

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71
Q

Slowly breathing could cause

A

Respiratory acidosis (more Co2 in the blood)

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72
Q

Hyperventilating could cause

A

Repiratory alkalosis

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73
Q

Which area of the lung has greatest ventilation

A

Base

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74
Q

Which area of the lung has poorest ventilation

A

Apex

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75
Q

What causes these regional variations in lung ventilation

A

Posture and gravity

Different starting volumes of the alveoli

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76
Q

Based on alveoli starting volumes, why is the apex the least vetilated

A

Larger starting volume –> lowest compliance

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77
Q

Based on alveoli starting volumes why is the base the best ventilated

A

Smaller starting volume, highest compliance

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78
Q

Define perfusion

A

The passage of fluid through the circulatory system to an organ or tissue

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79
Q

Pulmonary circulation has ________ pressure

80
Q

When is the pulmonary resistance the lowest

A

When lungs are at their functional residual volume

81
Q

Describe alveolar vessels

A

Surrounded on all sides by alveoli

82
Q

Resistance in alveolar vessels can be linked to

A

Transmural pressure and lung volume

83
Q

Resistance in extra alveolar vessels can be linked to

A

Intrapleural pressure

84
Q

Describe extra alveolar vessesl

A

Not surrounded by alveoli

85
Q

At TLC what is higher - Alveolar BV pressure or extra alveolar BV pressure

86
Q

At FRC what is higher - Alveolar BV pressure or extra alveolar BV pressure

A

Neither, both equal

87
Q

At RV what is higher - Alveolar BV pressure or extra alveolar BV pressure

A

Extra alveolar

88
Q

The total pulmonary vascualr resistance is the sum of

A

Alveloar BV resistance and extra alveolar resistane

89
Q

When is extra alveolar BV resistance at its lowest

90
Q

When is the resistance of alveolar vessels lowest

91
Q

When is extra alveolar BV resistance at its highest

92
Q

When is the resistance of alveolar vessels highest

93
Q

Describe the three stages of capillary recruitment from at a low pressure and then after an increase in P

A

1] Some BV collapsed, some open but dont conduct, some conducting
INCREASE PRESSURE
2] Previously non conducting conduct, previously closed open but dont conduct
INCREASE PRESSURE
3] Previously non conducting now conduct blood

94
Q

Capillary recruitment is a mechanism to

A

Accomodate an increase in pulmonary pressure and flow rate

95
Q

What is the reference point for pulmonary system circulation pressures

A

Outside of the heart at the level of the left atrium

96
Q

Typical Ppa

A

15 mm Hg

20 cm H2O

97
Q

Typical Ppv

A

8 mm Hg

10 cm H2O

98
Q

Ppa and Ppv change by what for every ______ ______ the level of the left atrium

A

Increase by 1 cm H2O below

Decrease by 1 cm H2O above

99
Q

Define Pa

A

Alveolar pressure relative to atmospheric pressure at point where there is no movement of air

100
Q

At the time there is no movement of air what can be said about Pa and Palv

A

Patm + P alv = 0

No difference

101
Q

What is Ptm

A

Transmural pressure across the wall of a vessel

102
Q

Three main factors which cause dilation

A

Inc Pa O2
Dec Pa CO2
Inc Pa pH

103
Q

Other factors which cause dilation

A 
Histamine (or other H2 agonists)
PGE1 PGI2
B adrenergic receptor agonists 
Bradykinin
Theophyline 
Acetylcholine 
NO
104
Q

Three main factors which cause constriction

A

Dec Pa O2
Inc Pa CO2
Dec Pa pH

105
Q

Other factors which cause contrstiction

A 
Histamine (H1 agonists)
Thromboxane A2, PGF 2a, PGE2
Alpha adrenergic receptor agonists 
Serotonin 
Angiontensin II
106
Q

In zone 1, which is higher Ppa or Ppv

A

Ppa is higher

107
Q

In zone 2, which is higher Ppa or Ppv

A

Ppa is higher

108
Q

In zone 3 which is higher Ppa or Ppv

A

Ppa higher

109
Q

Draw what would be seen at all 4 zones of the lungs

A

Refer to notes

110
Q

Define, ventilation:perfusion

A

Ratio of the rate of alveolar ventilation and the pulmonary blood flow

111
Q

Think of a small group of alveloi
If not ventilated ratio –>
Gas comp –>

A

Ration –> 0

Gas composition of the avleoli will become same a mixed venous blood 40 mmHg O2 46 mmHg CO2

112
Q

Mixed venous blood

Pressure of O2 and CO2

A

40 mmHg O2 46 mmHg CO2

113
Q

Think of a small group of alveloi
If not perfused ratio –>
Gas comp –>

A

To infinity
Gas comp of alveoli will become same as inspired humidified air
149 mmHg O2 0 mmHg CO2

114
Q

Gas comp of inspired humidifed air

A

149 mmHg O2 0 mmHg CO2

115
Q

V/Q at apex

116
Q

V/Q at base

117
Q

Average v/q

118
Q

Alveolar dead space ventilation (mismatch)

A

Local reduction in perfusion - e.g. due to a pulmonary embolism
No exchange so gas composition becomes same as inspired humid air
V/Q –> 0

119
Q

Describe a Shunt

A

Local reduction in ventilation

Because gas cant be removed from the area the gas composition becomes the same as mixed venous blood

120
Q

3 controls of airway diameter

A

Airway smooth muscle
Parasympathetic NS
Sympathetic NS

121
Q

3 controls for central control of respiration

A

Basic rhythm
Chemoreceptors
Stretch receptors

122
Q

A gq coupled pathway would have what effect on airway smooth muscle

A

Contraction

123
Q

Describe how the Gq coupled pathway causes contraction of the airway smooth muscle

A

Active Aq subunit (GTP bound)
Causes activation of PLC-b
PLC converts PIP2 to IP3 and DAG
DAG opens Ca channels in the membrane uses this Ca to activate PK-C –> causes growth
IP3 acts on intracellular calcium stores
Ca out of the stores combines with calmodulin to form calcium calmodulin
Calcium calmodulin phosphorylates mysoin light chain kinase causing activation and formation of cross bridges

124
Q

What (3) receptors are involved in the Gq coupled pathway

A

M3 muscarinic
H1 histamine
BK bradykinin

125
Q

Which G protein coupled pathway causes relaxation of the ariway smooth muscle

A

Gs coupled pathway

126
Q

How does a Gs coupled pathway cause relaxation of the smooth muscle

A

As with GTP bound
Activated adenylyl cyclase
ATP –> cAMP
Activation of PK-A - gene regulation/relaxation/channel regualtion/ - growth
Opening of BK K channels
Eflux of K - hyperpolarisation - closes Ca channels

127
Q

What receptors are involved in the Gs coupled patway

A

B2 adrenergic receptors

VIP receptors

128
Q

Which G protein coupled pathway oppsoes the relaxation of smooth muscle

129
Q

Describe how the Gi coupled pathway opposes the relaxation of smooth muscle

A

Inhibition of adenylyl cyclase
Counters the stim effects of Gi activation
Opposes relaxation of the smooth muscle
Also closes the BK K channels

130
Q

How does the parasympathetic division control the bronchial smooth muscle

A

Ach released from the vagus
Acts of muscarinic receptors
CONSTRICTION

131
Q

How does the sympathetic division control the bronchial smooth muscle

A

NA released from nerve terminals
Weak agonist
DILATION

132
Q

Does parasymp cause dilation or constriction

A

CONSTRICTIOn

133
Q

Does symp cause dilation or constriction

134
Q

Two humoral factors which interact with the airway smooth muscle

A

Circulating adrenaline and histamine

135
Q

Explain how adrenaline acts on the bronchial smooth muscle

A

Circulating in the blood
Better agonist
DILATIOn

136
Q

Explain how histamine acts of the bronchial smooth muscle

A

Released during the inflammatory processes

CONSTRICTION

137
Q

What is the feedback involved in the parasympathetic control of bronchial smooth muscle

A

M2 receptor on the postganglionic nerve terminal

138
Q

What receptors are found on the bronchial smooth muscle

139
Q

Describe the pathway after activation of one of the M3 receptors

A

Gq
Aq subunit with GTP bound
Activates PLC
PLC causes breakdown of PIP2 to IP3 and DAG
DAG –> Activates PK-C - Ca channels open (Ca in)
IP3 acts on intracellular calcium stores –> raised IC levels
Ca combines with calmodulin forming calcium calmodulin which then phosphroylates myosin light chain kinase (activating) - cross bridge formation

140
Q

Describe the pathway after activation of a sympathetic B2 receptor on the bronchial smooth muscle

A

Gs
As with GTP bound activated adenylyl cyclase
ATP –> cAMP
cAMP activates EPAC and PK-A
PK-A phosphorylates MLCK causing inhibition
PK-A causes opening of the BK K channel –> K eflux –> hyperpolarisation –> Ca channels close

141
Q

Asthma is characterised by having

A

Hyperactive airways

142
Q

Atopic is

143
Q

Give examples of some atopic triggers

A

Allergies, contact with inhaled allergens

144
Q

Give examples of some non-atopic triggers

A

Drugs, infections

145
Q

Non-atopic

146
Q

What is the response to the trigger in asthma

A

Inflammatory cells move into the airways
Release of inflammatory mediators - histamine
Bronchoconstriction

147
Q

What is seen in an asthma patients spirometry

A

Decrease in Fev1 and FEV1%

FVC ofen unaltered

148
Q

What receptors in asthma show an increase parasympathic activity

149
Q

What is significant about the M2 receptors in asthma

A

They show an increase in activity

150
Q

In asthma animal models what was seen in
m1 function
m2 function
m3 function

A

m1 - no change
m2 - decrease in neuronal m2 function
m3 - no change

151
Q

What did the antigen challenge reveal about M2 and eosinophils

A

Change in function linked to eosinophils
Eosinophils cluster around nerve fibres
Activated eosinophils released major basic protein
MBP inhibts the M2 receptors

152
Q

Short acting asthma treating

A

Salbutamol

153
Q

Long acting asthma treatment

A

Salmeterol

154
Q

Salmeterol must be administered with

A

Corticosteroids

155
Q

How may anticholinergics be used in the treatment of asthma

A

Block effects of endogenous Ach
E.g. tiotropium bromide
Inhaled 1x daily
Act via M1 and M3 receptors

156
Q

How can glucocorticoids be used to treat asthma

A

Anti-inflammatory action

Inhaled steroids such as beclomesadone

157
Q

What other drugs may be used to treat asthma

A

Theophylline

Leukotriene Modifiers

158
Q

Breathing is an _________ and __________ process

A

Automatic and rhythmical

159
Q

Basic respiratory rhythm is generated by

A

Centres in the medulla

160
Q

Two ways in which breathing can be consciously altered are

A

Hyperventilating and breath holding

161
Q

Activity in the hypoglossal nerve matches

A

Pre Botzinger Complex

162
Q

3 types of breath

A

Eupneic
Sigh
Gasp

163
Q

Two cell types of the pre-botzinger complex

A

Pacemaker cells and non pacemaker cells

164
Q

What two types of activity can be seen in pacemaker cells

A

Spiking - slow background depolarisation due to Na leak current
Bursting - membrane remains depolarised - activation of Na persistent channel

165
Q

What current does spiking rely on

A

Na leak current

166
Q

What current does bursting rely on

A

Na persistent current

167
Q

Which type of pacemaker activity is linked to an inspiration

168
Q

Activity in the pre botxinger complex leads to

A

BUrsting phase in neurones

169
Q

What is the NALCN

A

Sodium leak channel

170
Q

What is shown in mice which are knockouts for NACLN

A 
Die in 24hrs 
Cant maintian breathing pattern
Develop aponeia (lack of inspiration for certain time)
171
Q

What happens if EC [K] concentration is increased from 3mmol to 8mmol

A

Depolarisation of the cell
Takes the cell closer to the threshold value
Increased chanve of bursting
Increase period/ammount of bursting

172
Q

Transition to bursting is dependent on

A

Pesistent Na current (INaP)

CAN cation current (Ican)

173
Q

Pacemaker cells are split depending if they are sensitive to

174
Q

If Ican is relied on for bursting

A

Cadmium sensitive

175
Q

If Inap relied on for bursting

A

Cadmium insensitive

176
Q

If cells are cadmium sensitive what current is relied on for bursting

177
Q

If cells are cadmium insensitive what current is relied on for bursting

178
Q

Ican =

A

CAN cation current

179
Q

Inap

A

Persistent Na current

180
Q

What are some effects of hypoxia on the pre-Botzinger complex

A 
Eupenic --> Sighing --> Gasping 
EPSPs shut off for sighing but start again when gasping 
Autonomous spiking neurons drop off 
CS neurones drop off
CI neurones REMIAN
181
Q

What neurones are likely to be responsible for sigh breathing

A

Cadmium insensitive neurones

182
Q

What does the DRG control

A

Inspiration

183
Q

How does the DRG control inspiration

A

Sending signals to the inspiratory muscles

184
Q

Describe the activity of the DRG

A

Spontaneous

Active - shuts off - active

185
Q

When is the VRG inactive

A

During quiet respiration

186
Q

When is the VRG active

A

During forced respiration

187
Q

Does the pneumotaxic centre increase or decrease the rate

188
Q

How does the pneumotaxic centre increase rate

A

Has an inhibitory affect on inspiratory centre

Increases rate by shortening inspirations

189
Q

Does the apneustic centre increase or decrease the rate

190
Q

How does the apneustic decrease the rate

A

Stimulates the inspiratory centre

Increases the depth of breaths

191
Q

What is the the effect of the pneumotaxic centre on the inspiratory centre

A

Inhibitory

192
Q

What is the effect of the apneustic centre on the inspiratory centre

A

Stimulatory

193
Q

What does the Hering Breuer reflex prevent against

A

Over inflation of the ling

194
Q

Describe the hering breuer reflex

A

Inspiratory centre –> phrenic nerve –> diaphragm contracts –> strech receptor in the lung feeds back to the inspiratory centre via the vagus which has an inhibitory effect on the inspiratory centre

195
Q

Proof for hering breuer reflex

A

When no activity in the Vagus - phrenic nerve continues to fire causing contraction of the diaphragm even more. No shut off

BMS242 CVS Phys (12 decks)

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