Respiratory System Flashcards
To stay awake
1
Q
What are some common respiratory conditions?
A
Asthma Emphysema Cystic Fibrosis Chronic Bronchitis COPD (Chronic obstructive pulmonary disease)
2
Q
What are the main functions of the respiratory system?
A
Gas exchange (atmosphere + blood) (blood + tissue) Regulation of body pH (CO2 release) Vocalisation Protection Synthesis of hormones
3
Q
What forms the upper respiratory tract?
A
Nasal Cavity
Pharynx
Vocal Cord
Larynx
4
Q
What is the function of the upper respiratory tract?
A
Warm
Humidify
Filter
Vocalise
5
Q
What is asthma?
A
Respiratory condition caused by inflammation and spasms of the bronchioles. Usually triggered due to hypersensitivity.
6
Q
What is emphysema?
A
Air sacs of the lungs are damaged and enlarged. Common in smoking and causes breathlessness
7
Q
What is cystic fibrosis?
A
Production of thick mucus which leads to the blockade of bronchi, often results in respiratory infection.
8
Q
What forms the lower respiratory tract?
A
Trachea
Bronchi
Bronchioles
Alveoli
9
Q
What are the functions of the lower respiratory tract?
A
Conduct Air
Stabilise conductive airways
Regulate flow
Gas Exchange
10
Q
What keeps the trachea open?
A
U-shaped cartilage rings and the trachealis muscle.
11
Q
What important reflex does the trachealis muscle facilitate?
A
Coughing
12
Q
What keeps the bronchi open?
A
Cartilage Rings (Upper) Plates (Lower Parts)
13
Q
What is the function of goblet cells?
A
Secrete mucus to coat the respiratory tract
14
Q
What is the function of ciliated cells?
A
Sweep mucus upwards to the pharynx, to be swallowed
15
Q
What is the combined function of goblet and ciliated cells called?
A
The mucociliary escalator
16
Q
What is the structure of Bronchioles?
A
Small diameter
Smooth muscle walls
17
Q
How are bronchioles diameter regulated?
A
Histamines constrict bronchioles Parasympathetic NS (Acetylcholine induce bronchoconstriction) Sympathetic NS (Noradrenaline induces bronchodilation)
18
Q
What is the structure of Alveoli?
A
Single cell width
Side facing capillaries - ‘leaky’ for gas exchange
Supporting side - Elastic fibres (collagen IV) , robust
19
Q
What blood vessels supply the respiratory zone
A
Pulmonary Artery (deoxygenated blood) Capillary Network (Increases gas exchange) Pulmonary Vein (oxygenated blood)
20
Q
What is the respiratory zone?
A
Consists of the ends of the bronchioles, alveoli and the vessels that support them.
21
Q
How many types of Alveolar cells are there?
A
2-
Cell Type I (gas exchange)
Cell Type II (Production of surfactant)
22
Q
What does surfactant do?
A
Reduces surface tension and prevents alveoli from collapsing
23
Q
What are the pores of Kohn?
A
They allow for intra-alveolar ventilation
24
Q
What do macrophages do related to the alveoli?
A
They protect from small particles and ingest degraded surfactant
25
Which part of the respiratory tract has the highest resistance?
The bronchi
26
What does flow rate ely on?
Viscosity of the gas
Airway resistance
Flow pattern (turbulence)
27
What conditions can increase resistance?
Inflamed airways,
| Increased mucus secretion
28
What is a 'shunt'?
When blood from the bronchiolar artery draining into pulmonary circulation.
29
What membrane lines the thoracic wall?
The parietal pleura
30
What membrane lines the surface of the lungs?
Visceral Pleura
31
Why is intrapleural pressure less than atmospheric cavity?
As the lungs and chest wall are pulling away from each other.
32
What is boyle's law?
If volume increases, pressure will decrease
| P1 x V1 = P2 x V2
33
How does standing upright help breathing?
Gravity facilitates the diaphragm lowering.
34
What is lung compliance?
How easily the lung can be inflated and emptied
35
How do you calculate compliance?
Change in volume/change in pressure
36
What affects lung compliance?
The elasticity of the lung
| Surface tension in the alveoli
37
How is lung compliance limited?
As the college fibres have limited length
38
What is the law of LaPlace?
P =2T/r
39
What does a spirometer do ?
monitors the volume of air inspired and expired usually done under quiet breathing and no time restraitnts
40
What is a lung volume ?
A single difference
41
What is a lung capacity ?
the sum of 2 or more lung volumes
42
What is tidal volume ?
volume of air that moves during a single inspiration or expiration (500 ml)
43
What is inspiratory reserve volume ?
Additional air you inspire on top of tidal volume
44
What is expiratory reserve volume ?
Amount of air forcefully exhaled at the end of normal expiration
45
What is residual volume ?
the volume of air remaining in the respiratory system after maximum exhalation
46
What is vital capacity ?
inspiratory reserve volume + expiratory reserve volume + tidal volume
47
What is total lung capacity ?
vital capacity + residual volume
48
What is functional residual capacity ?
Expiratory reserve volume + residual volume
49
What are dynamic measurements ?
they assess the time taken to exhale a certain volume of air
50
What is FEV ?
forced expired volume
| How fast air leaves the airways in 1 second
51
What is FVC ?
Forced vital capacity
| the defined amount of air that can be forcibly exhaled from the lungs after taking the deepest breath possible
52
What are the characteristics of restrictive lung disease ?
FVC reduced
| FEV close to normal
53
What are the characteristics of obstructive lung disease ?
FEV reduced
| FVC close to normal
54
What is a pneumothorax?
Presence of air in the cavity between the lung and the thoracic cavity.
55
What factors affect gas exchange?
Sufrace area
Thickness of the membrane
Concentration gradient
Solubility of the gas
56
What is meant by the term dead space?
Airways that are ventilated but not designed for gas exchange (perfusion)
57
What is the consequence of dead space on alveolar air?
When breathing in 'used' air, remaining from previous expiration, re-enters the alveolar space and 'dilutes' the fresh air.
58
What does the fowlers method measure?
Anatomic dead space
59
What does dalton's law state?
The total pressure of a gas mixture is equal to the sum of partial pressures of the individual gases
60
How do you calculate diffusion capacity?
Rate of gas transfer from lung to blood/ driving partial pressure
61
How does emphysema affect gas exchange?
Destruction of alveoli means less surface area for gas exchange
62
How does asthma affect gas exchange?
Increased airway resistance decreases airway ventilation
63
How does pulmonary oedema affect gas exchange?
Fluid in interstitial space increases diffusion distance.
64
What are the boundaries of the thorax ?
posteriorly - thoracic vertebrae
laterally-ribs
anteriorly - sternum
65
How many thoracic vertebrae are there ?
12
66
What are the features of a typical thoracic verebra ?
body-heart shaped
spinous process-long and slender
articular process - on the body for the rib above
costovertebral facets - these are the superior and inferior demi facets
costotransverse facets - facets on the transverse processes
67
What are the features of a rib ?
head- facets for articulation with the demi facets in the vertebra
neck - enlarged bit is the crest
Tubercle - between the neck and the body - articulates with the facets on the transverse processes
Costal groove - on the internal inferior surface in which the neurovascular bundle runs
pit - joins to the costal cartilages
68
What are the 3 parts of the sternum ?
the manubrium , body and the xiphoid process
69
What are the 3 notches on the manubrium of the sternum ?
sternal notch
clavicular notch
notches for the costal cartilages of the first rib
70
What is the structure between the manubrium and the body of the sternum ?
the angle of louis or the sternal angle
71
What type of joint is the angle of louis ?
Symphysis
72
What structures bind the thoracic inlet ?
body of the first thoracic vertebra
1st rib
manubrium of the sternum
roofed by pleura
73
What does the thoracic inlet transmit ?
```
trachea
oesophagus
carotid artery
subclavian arteries
internal jugular veins
brachial veins
vagus nerve
phrenic nerve
```
74
What are the boundaries of the thoracic outlet ?
body of the 12th vertebra
lower ribs
xiphoid cartilage
closed by the diaphragm
75
What does the thoracic outlet transmit ?
```
oesophagus
dorsal aorta
inferior vena cava
vagus nerve
phrenic nerve
```
76
What are costovertebral joints ?
articulations between the facets on the head of the rib and the facts on demi facets on the vertebra
77
What type of joints are the costovertebral joints ?
synovial - depression and elevation
78
What are the costotransverse joints ?
articulations between the facets on the transverse processes and the tubercle of the rib
79
What are costochondral joints ?
joints between the costal cartilages and the distal ends of the ribs
synchondroses
80
What are chondrosternal joints ?
between costal cartilages and the sternum
81
What are interchondral joints ?
between the costal cartilges
82
What is the type of joint between the manubrium and the first rib ?
Synchondrosis
83
What type of action do ribs perform ?
lever action
84
What happens to the ribs in ventilation ?
they elevate causing an increase in thoracic dimensions
85
How do the a-p and transverse diameters increase ?
anterior rib ends rise and protrude more
86
What are the precise movements of ribs 3 and 6 ?
elevation occurs by rotation at the neck - increasing a-p dimensions
87
What are the precise movements of ribs 7 and 10 ?
elevation occurs by sliding outwards and backwards increasing transverse dimensions
88
What are the intercostal muscles ?
the external
the internal
the innermost
89
What do the external intercostal muscles do ?
pass from rib to rib in an anteroinferior direction
| they elevate the ribs in inspiration
90
What do the internal intercostal muscles do ?
pass from rib rib in perpendicular to the external intercostal muscles - they depress the ribs in inspiration
91
What do the innermost intercostal muscles do ?
the internal and the innermost muscles are separated by the neurovascualr bundles - intercostal arteries , nerves and veins - VAN
92
What is the thoracic cavity divided into ?
the right and left pleural cavities
| the mediastinum
93
What do the pleural cavities contain and what are they lined with ?
they contain the lungs and are lined with pleura
94
What are the 2 types iof pleura ?
parietal
| visceral
95
What is the parietal pleura ?
covers the inner aspect of the pleural cavity
96
What is the visceral pleura ?
covers the lungs
97
What is between the parietal and the visceral pleura ?
the pleural cavity - contains the pleural fluid
98
What is the costodiaphragmatic recess ?
a space between the lungs and the diaphragm created by the pleura
99
What are the fissures in the left lung ?
the oblique fissure creates the upper and lower lobes
100
What are the fissures of the right lung ?
the horizontal and the oblique fissures create the upper middle lower lobes
101
What is the depression found in the left lung ?
the cardiac notch to contain the heart
102
What is on the mediastinal aspect of each lung ?
the hilum of the lung - entrance for blood vessels and the tubes
103
What are the structures found in the hilum ?
primary bronchus
2 pulmonary veins
pulmonary artery
bronchial arteries - associated with the primary bronchus
104
What are the differences between the right and left primary bronchi ?
the right primary bronchus is wider and more vertical - more likely to find foreign bodies lodged in here
105
What are the 4 surfaces of the heart ?
apex
diaphragmatic surface
costal surface
mediastinal surface
106
Where can you find the intercostal NV bundle ?
running in the costal grooves of the ribs
107
Where does the intercostal nerve arise from ?
primary ramus of a thoracic spinal nerve
108
What are the branches of the descending aorta in the thorax ?
the posterior intercostal arteries and paired pericardial, oesophageal and bronchial arteries.
109
What is a bronchopulmonary segment ?
a segment of lung tissue with its own bronchus and blood supply which acts independent of other segments - can be removed without causing damage
110
Which branches of the subclavian artery provide an arterial supply to the thorax ?
internal thoracic artery and the costocervical trunk
111
What type of joints are formed between the head of the rib and the demifacets ?
synovial
112
How does the head of the rib articulate with the vertebra ?
the head of the rib articualtes with the same thoracic vertebra and the one above - form a full circle from the demi facets
113
What do ribs 11 and 12 lack ?
a transverse facet
114
What do the intercostal nerves supply ?
they supply the intercostal muscles and the skin supplying the space between the ribs
115
What is the origin of the sympathetic fibres found in the intercostal nerves ?
the ganglia of the sympathetic chain
116
Where do the fleshy fibres of the diaphragm insert ?
into the central tendon
117
What is the morphology of te diaphragm ?
double domed
118
What type of muscle is the diaphragm ?
skeletal muscle
119
What are the 2 recesses assocaited with the diaphragm ?
costomediastinal reccess
| costodiaphragmatic reccess
120
Where is the costodiaphragmatic recess ?
within the lung
121
Where is the costomediastinal recess ?
between the parietal pleura and the costal pleura
122
What are the attachments of the diaphragm ?
sternal
costal
verterbral
lumbocostal arches
123
What is the sternal attachment of the diaphragm ?
Xiphoid process
124
What is the costal attachment of the diaphragm ?
lower 6 costal cartilages
125
What are the vertebral attachments of the diaphragm ?
left and right cruae and lumbocostal arches
126
What are the right and left crue ?
they are the parts of the diaphragm that arise from the vertebrae
127
Where does the right crus arise from ?
arises from L1-L3 and some fibres form around the oesophageal opening
128
Where does the left crus arise from ?
from L1-L2
129
What are the types of lumbocostal arches ?
median and lateral
130
What are the 3 diaphragmatic apertures ?
caval
oesophageal
aortic
131
What is the aortic aperture ?
T12 Passes between the fibres of the 2 crura
132
What is the oesophageal apertures ?
made from the fibres of the right crura
| T10
133
What is the caval opening ?
the inferior vena cava passes through this opening in the central tendon at T8
134
What passes through the caval hiatus ?
the inferior vena cava
| right phrenic nerve
135
What passes through the oesophageal hiatus ?
oesophagus
| right and left vagus nerves
136
What passes through the aortic hiatus ?
descending aorta
thoracic duct
azygous vein
sympathetic chains
137
What is the motor innervation of the diaphragm ??
the anterior ramii of C3-C5 that form the phrenic nerve
138
What is the sensory innervation of the diaphragm ?
centrally - phrenic nerve
| laterally - lower 5 intercostal nerves
139
What are the functions of the diaphragm ?
```
ventilation-regulation of thoracic pressure
micturition
parturition
daefacation
lifting
```
140
What does the anterior abdominal wall consist of ?
1 central vertical muscle which is rectus abdominis
| 3 flat lateral muscles - internal oblique , external oblique and transversus abdominis
141
What is the transversalis fascia ?
a layer of fascia found depp to the transversus abdominis
142
What are the attachments of the rectus abdominis ?
attaches between the ribs and the pubic bone
| 3 transverse tendinous bands that join to the linea alba
143
What are the attachments of the external oblique ?
Arises from the lower 8 ribs and inserts into the linea alba , pubic bone , inguinal ligament and iliac crest
runs inferomedially
144
What are the attachments of the internal oblique ?
Runs superomedially
| Arises from below the pelvis and iliac crest and inserts into the costal margin and the linea alba
145
What are the attachments of the transversus abdominis ?
Arises from the lower 6 ribs and lumbar fascia , iliac crest and the inguinal ligament and inserts into the linea alba
146
What is the innervation of the muscles of the anterior abdominal wall ?
T7-L1 intercostal nerves which run between internal oblique and transversus abdominis
147
What are the functions of the muscles of the anterior abdominal wall ?
trunk movements
abdominal pressure regulation
expiration - accessory muscles
148
How much blood do the lungs receive per minute?
5l/min
149
How much air do the lungs receive per minute?
5l/min
150
Why is interpleural pressure less than atmospheric pressure?
Because the lungs and chest wall pull away from each other.
151
What challenges does the pulmonary circulation face?
The right ventricle can't generate high pressure.
152
How does the pulmonary circulation overcome its challenges?
The vascular resistance in the pulmonary circulation is 1/10th that of the systemic circulation.
153
How can you assess ventilation and perfusion in the lungs?
Insert a radioactive compound into airspaces of the lung and into veins of the lung.
'Mismatch' of compounds highlights areas where either ventilation or perfusion is affected.
154
What does V/Q stand for?
Ventilation/Perfusion ratio.
155
What can cause a high V?Q?
High alveolar O2 caused by vasodilation
| Low alveolar CO2 caused by bronchoconstriction
156
What is hypoxic pulmonary vasoconstriction (HPV)?
This is when small arteries in the lungs constrict in hypoxic conditions. This redirects blood flow to well ventilated regions increasing V/Q
157
How is HPV linked to birth?
In utero the lungs aren't ventilated, therefore after birth when O2 reaches the lungs HPV is lifted and perfusion greatly increases
158
What is COPD?
Chronic obstructive pulmonary disease
159
How is HPV linked to COPD?
In COPD ventilation in certain areas are low.
This trigger HPV.
Resistance increases, Pulmonary BP increases which could lead to right ventricular heart failure
160
What is venous admixture?
When blood passes through the lung without being properly oxygenated
161
What can cause venous admixture?
Anatomical Shunt - Blood bypasses the lungs through an anatomical channel
Low V/Q - When there is more blood in capillary than can be fully oxygenated (tumours, oedemas)
162
What are the risk of high levels of oxygen?
High levels may reduce ventilation and cause CO2 retention causing the pH to fall
Relatively little CO2 will enter the alveoli, this ay cause the alveoli to collapse
163
What is the direction of movement of Rectus Abdominis ?
downwards
164
What is the direction of movement of transversus abdominis ?
medially
165
What is the direction of movement of external oblique ?
inferomedially
166
What is the direction of movement of Internal oblique ?
Superiomedially
167
What is the solubility of oxygen?
3ml/l
168
What is the consumption of O2 at rest?
250 ml/min
169
FUCK THE ITALIANS!!!!
GO ESKIMOS
170
What is the required cardiac output to match consumption and solubility (without haemoglobin)?
84litres/minute
171
What would the heart rate be without haemoglobin?
Around 1200 beats/min
172
With haemoglobin what is the solubility of O2?
200ml/l
173
What is the over capacity of oxygen transport?
Under normal CO (5l) there is 4x over capacity
174
What is the structure of adult haemoglobin?
2 alpha subunit
2 beta subunits
4 haem groups
175
What is the structure of foetal haemoglobin?
2 alpha subunits
| 2 delta subunits
176
What % of erythrocyte mass is Hb?
Around 33%
177
Why do males have higher Hb % than females?
As androgens cause vasoconstriction.
178
Where does CO2 bind to haemoglobin?
The N-terminus of Hb
179
Why does the initial binding of 02 to a haem group promote further binding?
It forms an allosteric change in structure which promotes further binding.
180
What is 2-3 DPG (Diphosphoglycerate)?
Produced in RBC's, increases offload of oxygen to tissues at low P(O2)
181
What is important about Foetal Hb?
It has a higher affinity for oxygen than the maternal hb, this means it 'steals' oxygen from the mother blood.
182
What is Anoxia?
Complete deprivation of oxygen
183
What is hypoxia?
Reduced oxygen supply
184
What is cyanosis
02 saturated haemoglobin is purple. Reduced saturation causes bluish discolouration of the skin and mucous membranes
185
What is Hypercapnia?
Increased levels of CO2
186
How is CO2 spread in the body?
7% is soluble
23% is bound to Hb
70% is found in Bicarbonate
187
Why is bicarbonate important?
It is an important buffer in the blood
188
What is the Bohr effect?
Protons reduce Hb's affinity for O2
189
What is the haldane effect?
CO2 reduces Hb's affinity for O2
190
What are the main goals of the respiratory system ?
ensure alveolar ventilation is sufficient to maintain gas pressure
adapt ventilation to physiological or metabolic need
integrate ventilation with non respiratory activities
191
What do peripheral chemoreceptors sense ?
mainly oxygen
192
What are the 2 locations of the peripheral chemoreceptors ?
aortic bodies and the carotid bodies
193
How much of the response to oxygen to peripheral chemoreceptors mediate ?
100%
194
How much of the response to carbon dioxide do central chemorecepetors mediate ?
15%
195
Are peripheral or central chemoreceptors quicker at responding to carbon dioxide ?
peripheral
196
What potentiates the oxygen response ?
low pH and high co2
197
Where does the sensory information go ?
respiratory centre in the medulla
198
How does sensory info from the aortic bodies get to the respiratory centre ?
vagus nerve
199
How does sensory info get from the carotid bodies to the respiratory centre ?
glossopharyngeal nerve
200
What are type 1 glomus cells ?
peripheral chemoreceptors located in carotid bodies and aortic bodies
201
What are type 2 glomus cells involved in ?
support
202
What are the characteristics of glomus cells ?
well perfused - able to detect changes in oxygen quickly
| high metabolic rate - any drops in oxygen are detected
203
Is there a high intensity of signal transmission when you remove oxygen ?
yes - via the glossopharyngeal nerve
204
Is there a higher rate of ventilation or lower when co2 increases and pH drops ?
higher - more signla transmission via the glossopharyngeal nerve
205
How is a low oxygen level detected ?
```
low oxygen in the blood
potassium channels close
cell depolarises
voltage gated calcium channels open
calcium entry
exocytosis of dopamine vesicles
binding of dopamine receptors
signals to medullary centres to increase ventilation via glossopharyngeal
```
206
At what pressure of oxygen does ventilation start to become responsive to low O2 ?
60 mmHg
207
What is the effect of decreasing oxygen as well as carbon dioxide on the ventilatory response ?
potentiates the response - slope become steeper as both stimuli come together to stimulate the ventilatory response
208
What is the main parameter for the ventilatory response ?
carbon dioxide
209
What is the blood-brain barrier impermeable to ?
bicarbonate and protons
210
What easily diffuses across the blood-brain barrier ?
carbon dioxide
211
What happens to c02 in the cerebral capillaries ?
co2 diffuses across the BBB into the CSF where the reaction with water (catalysed by carbonic anhydrase) turns into carbonic acid and then protons and bicarbonate
212
What happens to the protons ?
they are detected by the central chemoreceptors
| signals sent to respiratory control centre and there is increased ventilation to counter act
213
Where are the central chemoreceptors located ?
in the venterolateral surface of the medulla and are bathed in CSF
214
What does an increase in Co2 do to ventilation ?
linear response
215
At what level of c02 is there no change in ventilation ?
30 mmhg
216
What happens if oxygen and carbon dioxide levels are both decreased ?
the 2 stimuli potentiate other - oxygen and carbon dioxide have synergic effects
217
What effect does acidosis have on the ventilation rate ?
there is a higher ventilation rate - steeper slopes representing more sensitivity - the proton and the carbon dioxide response potentiate one another to produce a bigger change in ventilation
218
What happens during sleep or a narcotic overdose ?
there is a reduced sensitivity to oxygen (right shift)
| higher tolerance of co2
219
What happens in heroin overdose ?
less response to carbon dioxide
forget to breathe
autonomous activity not stimulated enough
220
What happens in the instance of 'death in shallow water' ?
hyperventilation reduces pCO2 (30 mmhg-no response) and a moderate increase in oxygen
the ventilatory drive is reduced and the oxygen deficit is overruled so ventilation decreases - die due to o2 deficit
221
Where are peripheral chemoreceptors located ?
carotid bodies and aortic arch
222
What do peripheral chemoreceptors sense ?
pH co2 and O2
223
What is the relative speed of peripheral chemoreceptors ?
relatively quick
224
Where are central chemoreceptors located ?
floor of the 4th ventricle bathed in CSF
225
What do the central chemoreceptors sense ?
c02
226
`What is the relative speed of central chemoreceptors ?
relatvely slow
227
What provides the major ventilatory drive for central chemoreceptors ?
carbon dioxide
228
What are the advantages of using a carbon dioxide based system ?
carbon dioxide production is related to oxygen consumption
Carbon dioxide production is related to pH
Linear relationship - Carbon dioxide changes are buffered by changes in pH
229
What are the 3 types of receptors related to vagal afferent reflexes ?
slowly adapting pulmonary stretch receptors
rapidly adapting pulmonary receptors (irritant)
J receptors
230
Where are the stretch receptors located ?
large airways and the visceral pleura
231
What do the stretch receptors detect ?
stretch detected by thoracic cavity expansion
232
What is the effect of activating the stretch receptors ?
signals are sent to he respiratory centre when expanded enough to terminate inspiration and limit tidal volume
extedn expiration
233
What is an exmaple of the use of stretch receptors ?
herring-breuer reflex
234
Where are peripheral chemoreceptors located ?
carotid bodies and aortic arch
235
What do peripheral chemoreceptors sense ?
pH co2 and O2
236
What is the relative speed of peripheral chemoreceptors ?
relatively quick
237
Where are central chemoreceptors located ?
floor of the 4th ventricle bathed in CSF
238
What do the central chemoreceptors sense ?
c02
239
`What is the relative speed of central chemoreceptors ?
relatvely slow
240
What provides the major ventilatory drive for central chemoreceptors ?
carbon dioxide
241
What are the advantages of using a carbon dioxide based system ?
carbon dioxide production is related to oxygen consumption
Carbon dioxide production is related to pH
Linear relationship - Carbon dioxide changes are buffered by changes in pH
242
What are the 3 types of receptors related to vagal afferent reflexes ?
slowly adapting pulmonary stretch receptors
rapidly adapting pulmonary receptors (irritant)
J receptors
243
Where are the stretch receptors located ?
large airways and the visceral pleura
244
What do the stretch receptors detect ?
stretch detected by thoracic cavity expansion
245
What is the effect of activating the stretch receptors ?
signals are sent to he respiratory centre when expanded enough to terminate inspiration and limit tidal volume
extedn expiration
246
What is an exmaple of the use of stretch receptors ?
herring-breuer reflex
247
Where are rapidly adapting (irritant) pulmonary receptors found ?
underneath airway epithelium at bifurcations
248
What do rapidly adapting pulmonary receptors (irritant) detect ?
flow (rate of change)
249
When are rapidly adapting receptors most active ?
when a person inhales noxious substances
250
Where are pulmonary C fibre (J receptors) found ?
juxtapulmonary capillaries
251
When are J receptors triggered ?
when the lung is diseased - pulmonary eedema and the release of histamine
252
What type of breathing pattern is triggered with the J receptors ?
aponea followed by rapid shallow breathing
253
What are the 2 neurogenic control systems ?
voluntary and involuntary
254
Which part of the brain initiates voluntary control ?
cerebral cortex
255
Where are the signals from the voluntary control system sent ?
respiratory centre in the medulla
256
What produces the response in the voluntary control system ?
respiratory muscles
257
Inhibitory and excitatory neurones display what ?
reciprocal innervation - they are mutually inhibitory
258
The voluntary and involuntary systems are ....
independent of one another and can be overrriden
259
What do both the voluntary and involuntary systems require ?
descending pathways - alpha motoneurones to the respiratory muscles and descneding pathways
260
Which muscle system controls the muscles of respiratory ventialtion ?
somatic motor system
261
What does the Autonomic nervous system control ?
smooth muscle contraction and secretion
262
Where are the 2 respiratory centres ?
in the pons and the medulla
263
What is the role of the pons ?
modulation
264
What is the role of the medulla ?
the medulla is the site of the rhythmic respiratory centre and it generates the automatic breathing pattern
265
What is the medulla made of ?
2 groups of neurones - the DRG and the VRG
266
What does the DRG do ?
generates the inspiration firing pattern and hence the inspiratory drive
output via the phrenic nerve activates respiratroy muscles and initiates inspiration
267
What does the VRG do ?
mainly expiratory neurones (at the ends)
| some inspiratory neurones are found in the pre-botzinger complex
268
What is the pre-botzinger complex ?
found in the VRG centrally
| a rhythm generator - cells within it generate the basic rhythm
269
Destruction of the VRG and the DRG leads to ?
immediate and permanent termination of automatic respiration
270
During inhalation what is the activity of inspiratory neurones , phrenic nerve and the external intercostal nerves ?
inspiratory neurones fire
phrenic nerve increases activity
external intercostal nerves fire
271
During exhalation what is the activity of the phrenic , expiratory neurones and internal intercostal neurones ?
expiratory neurones fire
reduced activity of the phrenic and the external intercostal
internal intercostal neurones fire
272
What is cheyne-stokes respiration ?
deeper and faster breathing followed by apnea
273
What causes cheyne-stokes respiration ?
over and under correction of pC02 due to increased transit time between the lung and the carotid body
274
The conducting airways are .. ?
ventilated but not perfused
275
The conducting airways are known as ?
dead space - no gas exchange takes place
276
Why does some air enter the respiratory system but not reach the alveoli ?
because part of each breath remains in the airways like the trachea and the bronchi
277
What is the anatomic dead space ?
the volume of the conducting airways (150 ml)
278
What is the alveolar dead space ?
the volume of air in the alveoli that is ventilated but not perfused due to V/Q mismatch
279
What is the physiologic dead space ?
anatomic air space + alveolar dead space
280
In animals how big is the anatomic dead space ?
1/3 of tidal volume
281
What happens in the dead space at the end of inspiration ?
the anatomic dead space is filled with fresh air at the end of inspiration (150)
282
What happens in the dead space during expiration of tidal volume ?
the first exhaled air comes out of the dead space
150 ml comes out the dead space
350 ml is left in the alveoli
283
What happens to the dead space at the end of expiration ?
it is filled with stale air
284
If you inhale 500 ml of air what happens ?
the dead space is filled with air (150)so this goes to the alveoli- so only 350 actually reaches the alveoli
285
How can we measure anatomic dead space ?
using fowlers method
286
Describe fowlers method ?
one breath of pure oxygen (any gas that doesnt contain nitrogen)
gas that doesnt take place in alveolar gas exchange is exhaled first and the alveoalr air
287
What does henrys law state ?
the amount of gas dissolved in a liquid is determined by the partial pressure of the gas and its solubility in the liquid
288
What is the order of solubility of co2 , o2 and n2 ?
CO2 > O2 > N2
289
Oxygen being poorly soluble is compensated by the fact that ?
it has a large pressure gradient
290
What compensates for the low c02 pressure gradient ?
the high solubility of carbon dioxide
291
How is diffusion capacity optimised in the lungs ?
the shape of type 1 alveoalr cells
| fused basement membranes
292
What does diffusion capacity measure ?
the amount of gas travelling from the alveolar dead space to the blood
293
How do you calculate diffusion capacity ?
rate of gas transfer from lung to blood / driving partial pressure
294
What does diffusion capacity depend on ?
solubility of the gas
295
When is Diffusion capacity impaired ?
in respiratory diseases
296
Which parts of the lung are poorly perfused and why ?
apex due to limited force of contraction of the right ventricle
297
What does the efficiency of the lung depend on ?
diffusion and perfusion
298
What happens in a perfusion limited scenario ?
there is not enough blood to carry away thr gas transferred
rapid transfer of gas between the alveolus and the blood
equilibrium is reached before the end of the capillary bed
299
Which molecules are perfusion limited ?
n20 and 02
300
What happens in a diffusion limited scenario ?
slow transfer of gas across the blood and alveolus interface
equilibrium is not reached in transit time
301
The lung receives how much blood from the cardiac output ?
5L / min
302
How can we measure ventilation using Xe 133 ?
Xe 133 is inhaled and it distributes evenly in the alveolar space
radiograph shows that the apex is fainter showing that it is well ventilated
303
What is the normal ventilation/perfusion ratio ?
1 (5/5)
304
At the beginning of inspiration intrapleural pressure is what ?
-3 mmhg
305
As inspiration proceeds what do the pleural membranes and lungs do ?
they follow the expanding rib cage
306
Why is intrapleural pressure less than atmospheric pressure ?
because the lungs and chest wall pull away from each other
307
What effect does gravity have on the alveoli ?
the weight of the lung means that alveoli at the base are compressed whilst alveoli at the top are distended
308
Where are ventilation and perfusion efficient ?
at the base rather than the apex
309
What happens at the apex ?
perfusion and ventilation are low
| the alveoli are distended so they squeeze the capillaries and ventilation > perfusion
310
If ventilation is high at the apex what does this mean ?
there is a low amount of co2 and therefore a high pH
311
What happens at the base of the lung ?
volume is higher
V/Q in favour of perfusion
low hydrostatic pressure to overcome
po2 is lower and pco2 is higher - lower pH
312
How can we assess ventilation and perfusion ?
Xe 133
313
How can we measure ventilation using Xe 133 ?
Xe 133 is inhaled and it distributes evenly in the alveolar space
radiograph shows that the apex is fainter showing that it well ventilated
314
How can we measure perfusion using Xe 133 ?
Xe 133 is injected and leaves the blood quickly as it is poorly soluble - via the lungs
radiograph shows that apex is poorly perfused
315
How would a pulmonary embolus appear on a Xe radiograph ?
embolus blocks perfusion - no gas transfer - no stain
316
What is the pattern of blood flow from the base to the apex ?
blood flow decreases from the base the apex
317
What is the response of the lung to a high V/Q ?
vasodilation - increase blood flow to remove co2
| bronchoconstriction- reduce air flow so that V and Q are matched
318
What is the response of the lung to a low V/Q ?
bronchodilation - increase oxygen and remove carbon dioxide as there is a lot of perfusion
hypoxic pulmonary vasoconstriction - allows more oxygen to enter the blood as it lowly ventilated
319
Hypoxic pulmonary vasoconstriction occurs where ?
pulmonary arterioles
320
What happens in the systemic circulation during hypoxic conditions ?
vasodilation
321
What type of response is hypoxic pulmonary vasoconstriction ?
local
322
What is HPV independent of ?
autonomic nervous system
323
What is HPV still responsive after ?
sympathectomy
vagotomy
chemoreceptor destruction
324
How is an oxygen disbalance sensed in smooth muscle cells ?
cells sense a disbalance between ATP and ADP
moreADP means low o2
ADP to AMP to AMP kinase
affects membrane potential via a voltage gated channel
allows calcium to enter via voltage gated channels
325
How is the V/Q mismatch balanced again ?
reduction in oxygen supply to the alveolus
reduced oxygen gradient into the blood
blood not fully oxygenated
pulmonary capillary constriction
blood supply rediced in the hypoxic region and diverted to the well oxygenated areas
326
Why is there a lower pressure of oxygen in the pulmonary capillaries compared to the arteries ?
```
anatomical shunt (blood from systemic arterioles drains directly into pulmonary veins)
V/Q mismatch
```
327
What is venous admixture ?
occurs when the blood passes through the lung withour being oxygenated properly
328
What can left ventricular heart failure lead to ?
increase in pulmonary pressure due to backlog
hydrostatic pressure/oncotic pressure balance disturbed
water is trapped - pulmonary odema
329
What happenns in asthma ?
bronchoconstriction - harder to exhale
330
What happens in emphysema ?
surrounding tissue doesn't support bronchioles - bronchioles collapse
331
What are the dangers of giving oxygen ?
the o2 dissociation curve predicts that even at higher o2 concentrations not much more H b is saturated
increased o2 reduces ventilation
causes co2 retention
acidosis
all the o2 may enter the elveoli whilst co2 doesnt leave the blood - ateclasis
332
How does ventilation change with work rate ?
ventilation increases linearly with work rate
333
What happens when peak oxygen consumption has been reached ?
body reverts to glycolysis to get more energy
334
What are the changes to ventilation during exercise ?
increase in tidal volume
increase in ventilation rate
increased diffusion capacity
increased recruitment of capillaries for GE
335
Why does arterial pH continue to drop even when carbon dioxide levels drop ?
lactic acid production
336
What stimulates pulmonary ventilation in exercise ?
motor cortex
proprioceptors and the muscle spindle
lung stretch receptors
increase in K concentration due to repolarisation
337
What is the most adaptive response to low O2 ?
hypoxic response
low o2 detected by peripheral chemoreeptors in the aortic body and the carotid bodies
signal to the respiratory centre in the medulla
causes hyperventialtion
338
What are the consequences of hyperventilation ?
```
blows off extra co2
increase in pH leading to alkalosis
increases affinity for 02
decrease in c02 reduces the ventilatory drive
mediated by central chemoreceptors
```
339
How is pulmonary oedema caused at high altitude ?
low 02 triggers HPV
this increases pulmonary pressure
disturbs the balance between oncotic and capillary pressure
leads to fluid
340
What is the long term adaptation to high altitude ?
bicarbonate is transported out of the CSF
this reduces the pH of the CSF
resets central chemoreceptors and makes them more sensitive to co2
increase ventilatory drive
341
What takes care of the bicarbonate concentrations in the blood ?
kidney
342
What doe ssutained hypoxia trigger ??.
the release of 2,3 DPG
shape of the o2 dissociation curve moves to the right
leads to a lower affinity for 02 so that it is readily released in the tissues
343
How is 02 carrying capacity increased at high altitude ?
hypoxia stimulates erythrocyte production
EPO is released from the kidneys
haemopoiesis in the bone marrow
50% increase in RBC levels
344
What are the consequences of having higher RBCs levels in the blood ?
increased viscosity of blood
| heart has to pump harder
345
What leads to frostbite and gangrene ?
peripheral vasoconstriction in lower temperatures
| reduces the circulation of blood
346
What are the short term changes to high altitude ?
increased pulmonary pressure
promotes recruitment of more capillaries
number and size of mitochondria increase - more aerobic metabolism
347
What are the long term changes to high altitude ?
body develops more capillaries in response to high altitude - increases oxygen diffusion
348
What are the early changes in response to high altitude ?
increased ventilation
increased HR
increased 2,3 DPG
349
What are the later changes to high altitude ?
increased RBCs
350
If the diameter of a bronchiole is halved , the flow drops by a factor of ?
16
| pouiselles law
351
Lung compliance is ?
change in volume/ change in pressure
352
Which disease increases lung compliance ?
emphysema
353
Average arterial co2 pressure is ?
40 mmHg
354
Average arterial o2 pressure is ?
100 mmHg
355
What balances the V/Q mismatch ?
hypoxic pulmonary vasoconstriction
356
What do peripheral chemoreceptors sense ?
02 below 60 mmHg
