Respiratory Physiology Flashcards
1
Q
What are the 4 functions of the respiratory system?
A
Gas exchange
Acid base balance
Protection from infection
Communication via speech
2
Q
What gas is added from the air to the blood?
A
O2
3
Q
What gas is removed from the blood into the air?
A
CO2
4
Q
What is the respiratory system responsible for?
A
Acquiring oxygen
Removing carbon dioxide
5
Q
What system does the respiratory system need?
A
The cardiovascular system
6
Q
Where does the cardiovascular system transport oxygen?
A
To tissues
7
Q
Where does the cardiovascular system transport carbon dioxide?
A
Away from tissues
8
Q
What does cellular respiration need?
A
Oxygen
9
Q
What is the waste product of cellular respiration?
A
Carbon dioxide
10
Q
Where does the pulmonary artery travel?
A
Away from the heart
11
Q
Where does the pulmonary vein travel?
A
Towards the heart
12
Q
What is the function of pulmonary circulation?
A
Deliver CO2 to lungs and pick up O2
13
Q
What is the function of systemic circulation?
A
Deliver O2 to cells
Remove CO2 from cells
14
Q
In the steady state what is the relationship between the gases exchanged in the lungs and tissue?
A
The net volume of oxygen and carbon dioxide exchanged in the lungs per unit of time is equal to the net volume exchanged in the tissues
15
Q
What does gas exchange being equal in the lungs and tissues prevent?
A
The build up of gas in the circulation
16
Q
What is the main organ of the respiratory system?
A
Lungs
17
Q
What is a common name for the larynx?
A
Voice box
18
Q
Where does air enter the body?
A
Through the nose
19
Q
How many trachea are there?
A
1
20
Q
How many bronchus are there?
A
2
21
Q
What is the epiglottis?
A
Small flap of tissue that folds over the trachea preventing food from entering the air pipe when you swallow
22
Q
What does the upper respiratory system compose of?
A
Mouth
Nasal cavity
Pharynx
Larynx (voice box)
23
Q
What does the lower respiratory system compose of?
A
Trachea
Bronchi
Lungs
24
Q
How is the patency of airways maintained?
A
By C shaped rings of cartilage
25
Where can gas exchange occur?
Alveoli
| Systemic Capillaries
26
What organ lying inferior to the right lung causes is to be shorter and broader?
The liver
27
What are the 2 fissures of the right lung?
Horizontal fissure
| Oblique fissure
28
How many bronchi does the trachea branch into?
2
29
How many more times does each bronchus branch?
22
30
Where does the bronchus terminate?
At the alveoli
31
Why are the alveoli covered in capillaries?
To minimise the distance of exchange
32
What are the alveoli covered in?
Elastic fibres
| Capillaries
33
Describe the walls of the alveoli?
Thin walls
34
Why does gas not exchange at the upper airways?
Because the walls are too thick
35
What is the air in the upper airways known as and why?
Anatomical dead space
| Because it cannot participate in gas exchange
36
What features of the alveoli make it so effective for gas exchange?
Thin walls
| Large surface area
37
What is airway diameter altered by?
Activity of bronchial smooth muscle
38
What is the function of mucous in the respiratory tract?
To moisten the air
To trap large and invasive particles
To provide a large surface area for cilia to work on
39
What cells produce mucous in the respiratory tract?
Goblet cells
40
What type of epithelium lines the respiratory tract?
Psuedo-stratified, ciliated, columnar
41
What hair like structures line the respiratory tract?
Cilia
42
In terms of pressure how do gases move?
From an area of high pressure to an area of low pressure
43
What does Boyle's Law state?
The pressure exerted by a gas is inversely proportional to its volume
44
What does Daltons Law state?
The total pressure of a gas mixture is the sum of the pressure of the individual gases
45
What does Charles Law State?
The volume occupied by a gas is directly related to the absolute temperature
46
What is the lower respiratory system bound by?
Diaphragm
Spine
Ribs
47
How many lobes is the right lung split into?
3
48
How many lobes is the left lung split into?
2
49
What volume of pleural liquid is there in the pleural cavity?
3ml
50
What is function of pleural liquid?
To act as a lubricant
51
How many pleural membranes is each lung enclosed by?
2
52
What are the 2 pleural membranes?
Parietal pleura
| Visceral pleura
53
What is inflammation of the pleural membranes known as?
Pleurisy
54
What is the purpose of the pleural membranes?
To anchor the lungs to the rib cage
55
What does the parietal pleural membrane coat?
The inner surface of the lungs
56
What does the visceral pleural membrane coat?
The outer surface of the lungs
57
Explain pneumothorax
When there is a loss of relationship of the pleural membranes
The chest wall wants to expand
The lung wants to shrink
Leads to the collapse of the lung
58
What muscles are used for inspiration?
Diaphragm
External intercostal muscles
Scalenes
Sternocleidomastoids
59
What muscles are used for expiration?
Internal intercostal
| Abdominals
60
What is the very basic concept of breathing?
There is an increase of volume in the thoracic cavity
This decreases the pressure
Drawing air from higher pressure outside in
61
Is inspiration passive?
No
62
Is expiration passive?
Yes - AT REST
63
When the diaphragm contracts what happens?
It moves down
| Increasing thoracic volume
64
What is the intra-thoracic (alveolar) pressure?
The pressure inside the thoracic cavity
65
Is the intra thoracic pressure + or -?
Can be either compared to the atmospheric pressure
66
What is the intra-pleural Pressure?
Pressure inside pleural cavity
67
Should the intra-pleural pressure be + or -?
Always negative (in healthy lung at least)
68
What is the transpulmonary pressure?
Difference between the alveolar pressure and intra-pleural pressure
69
What is the major determinant of airway resistance?
The radii of the airways
70
Are the lungs elastic?
Yes they are elastic structures
71
Explain expiration
The inspiratory muscles cease to contract
Allowing elastic recoil of chest wall
Lungs return to normal size
Smaller volume - greater pressure than atmospheric
Driving air out of the lungs
72
What do type I alveolar cells do?
Permit gas exchange
73
What do type II alveolar cells do?
Secrete surfactant fluid
74
What volume of gas does the average person breathe in and out in a breath?
500ml
75
What is tidal volume?
The normal inspiration and expiration of gas
76
What is the average volume of tidal volume?
500ml
77
What volume of air is the anatomical dead space?
Around 150ml
78
What volume is the inspiratory reserve volume?
3L
79
What volume is the expiratory reserve volume?
1.1L
80
Why is the residual volume in the lungs so crucial?
Prevents the alveoli from collapsing
81
What is the vital capacity?
The maximum expiration after the maximum inspiration
82
What is pulmonary ventilation?
Total air movement into-out of the lungs
83
What is alveolar ventilation?
The fresh air getting to alveoli and therefore available for gas exchange
84
Is the anatomical dead space air available for gas exchange?
No
85
Between what volumes do the lungs normally operate?
2.3L and 2.8L
86
How do you work out the air that reaches the alveoli?
Vol of air breathed in - 150ml of the dead space air
87
What affects the amount of air that reaches the alveoli? Rate or depth of breathing?
Depth
88
What do type I alveolar cells permit?
Gas exchange
89
What do type II alveolar cells secrete?
Surfactant fluid
90
What does surfactant fluid reduce?
Surface tension on alveolar surface
91
What does the compliance of the lung represent?
The stretchability of the lung
| How easy it is for air to get into the lungs
92
Is low compliance good or bad?
Bad
93
What happens to the compliance of our lungs with age?
Become less compliant
94
Describe high compliance?
Large increase in lung volume for small decrease in ip pressure
95
Describe low compliance?
Small increase in lung volume for large decrease in ip pressure
96
What is the definition of compliance?
The change in volume relative to the change in pressure
97
During inspiration what needs to be overcome?
Surface tension
98
What does a shallower curve represent?
Lower compliance
99
What does a steeper curve represent?
Higher compliance
100
What is emphysema?
Loss of elastic tissue meaning expiration requires effort
101
What is fibrosis?
Inert fibrous tissue means effort of inspiration increases
| As the stretchability of the lung is affected
102
What is the pleural membrane coating the outer surface of the lungs?
Visceral membrane
103
What is the pleural membrane coating the inner surface of the ribs?
Parietal membrane
104
Is inspiration passive?
No
| Inspiration requires energy
105
Upon inspiration does the diaphragm ascend or descend?
Descend
106
Why does the diaphragm descend upon inspiration?
To increase thoracic volume
107
What happens with asthma?
There is an over-reactive constriction of bronchial smooth muscle.
Increasing resistance making expiration of air difficult
108
Why is intrapleural pressure always negative?
So it acts like a suction to keep the the lungs inflated
109
What is the bulk flow of air between the atmosphere and alveoli proportional to?
The difference between the atmospheric and alveolar pressures
110
What is the bulk flow of air between the atmosphere and alveoli inversely proportional to?
Airway resistance
111
Describe the end of a unforced expiration
The dimensions of the lung and thoracic cage are stable as the result of opposing elastic forces
The lungs are stretched and attempt to recoil
The chest wall is compressed and attempting to move outwards
112
What is the major determinant of airway resistance?
The radii of the airways
113
What does airway resistance determine?
How much air flows into the lungs at any given pressure
114
Does the increase in thoracic volume make the intrapleural pressure more negative or positive?
Negative
115
What is vital capacity?
Tidal volume
+ ERV
+ IRV
116
What is TLC?
Total lung capacity
| Vital capacity + Residual volume
117
At birth what volume do babies lack?
Residual volume
118
What is hyperventilation?
When more air than normal reaches the alveoli
| I.e when taking deep breaths
119
What is hypoventilation?
When less air than normal reaches the alveoli
| I.e when taking shallow breaths
120
How do you measure the air to alveoli?
The tidal volume minus 150ml
121
What unit is pressure commonly expressed in?
mmHg
122
During hyper ventilation what does PO2 rise to?
120mmHg
123
During hyper ventilation what does PCO2 fall to?
20 mmHg
124
During hypo ventilation what does PO2 fall to?
30 mmHg
125
During hypo ventilation what does PCO2 rise to?
100mmHg
126
Why is the residual volume impossible to squeeze out ?
It stops the alveoli from collapsing
127
What is ventilation?
The movement of air in and out of the lungs (breathing)
128
What percentage of air in the alveoli is fresh?
70%
129
What cells produce surfactant?
Type II alveolar cells
130
What is the role of pulmonary surfactant?
To act like a detergent
Reducing the surface tension on the alveolar surface
Reducing the tendency for the alveoli to collapse
131
What molecular interactions of the alveoli does pulmonary surfactant interrupt?
Acts like a detergent
| Interfering with the water molecule interactions on the alveoli
132
Why does pulmonary surfactant increase the compliance of the lungs?
As it reduces the lungs tendency to recoil
| You do not have to apply extra pressure to stop the alveoli from collapsing
133
When does surfactant pulmonary production start?
25 weeks
134
Normally what is the expectation of healthy lungs regarding compliance?
Expected to be highly compliant
135
Is compliance related to elasticity or stretchability?
Stretchability
136
Describe high compliance of the lungs?
A large increase in lung volume for small decrease in ip pressure
137
Describe low compliance of the lungs?
A small increase in lung volume for large decrease in ip pressure
138
Why is low compliance bad?
Requires alot of effort for a small increase in lung volume
139
Does compliance increase or decrease with age?
Decrease
140
Where is alveolar ventilation greatest?
At the base of the lung
141
Where is alveolar ventilation the least?
At the apex of the lung
142
Why is alveolar ventilation greatest at the base of the lung?
Because the weight of the lung is pushing down on the base
| Meaning the base of the lung has more potential to expand
143
What does a shallower curve in pressure volume graph indicate?
Lower compliance
144
What does a steeper curve on pressure volume graph indicate?
Higher compliance
145
What does low compliance indicate?
A stiff lung
146
What does high compliance indicated?
A pliable lung
147
What is obstructive lung disease?
When there is obstruction to the flow of air especially on expiration
148
Does obstructive lung disease particularly affect inspiration or expiration?
Expiration
149
What does restrictive lung disease restrict?
Lung expansion
| Compliance
150
What happens to alveolar ventilation from the base to the apex of the lung?
It declines
151
What happens to compliance from the base to the apex of the lung?
It declines
152
Give 2 examples of obstructive lung disorders
Asthma
COPD
Chronic bronchitis
Emphysema
153
What is lost in emphysema?
Lung elasticity
154
What is chronic bronchitis?
Inflammation of the bronchi
155
What is infant respiratory distress syndrome?
When there is insufficient surfactant production in the babies lungs
Surfactant production normally occurs at around 23 weeks
156
What is oedema of the lungs?
Build up of fluid around the alveoli
157
Is oedema restrictive or obstructive?
Restrictive
158
What test is used to measure lung function?
Spirometry
159
Is voluntary or involuntary lung action measured with a spirometer?
Voluntary
160
What can be measured using spirometry?
Tidal volume
Inspiratory RV
Expiratory RV
Vital Capacity
161
What is FEV1?
The forced expiratory volume in 1 second
162
What is FVC?
The forced vital capacity
163
In healthy individuals what should the forced expiratory volume be?
80% of the vital capacity
164
Why does obstructive lung disease show a decrease in Vital capacity and FEV?
Because obstruction means they cannot blow as much air out in 1 second
165
Why does restrictive lung disease show an increase in %?
Because the problem was getting the air in
| Meaning they can get the air out quicker as they technically do not have enough in their lungs to begin with
166
What are the 2 different blood supplies to the lungs?
Bronchial circulation
| Pulmonary circulation
167
What is the bronchial circulation supplied by?
The bronchial arteries
| It is the nutritive one
168
Explain bronchial circulation
Arises from systemic circulation
| Supplies oxygenated blood to the airways smooth muscle, nerves and lung tissue
169
What is the pulmonary circulation used for?
Gas exchange
170
Is the pulmonary circulation a high or low pressure system?
Low
171
Is the pulmonary circulation a high or low flow system?
High
172
Where do the left and right pulmonary arteries arise from?
Right ventricle
173
Where does the pulmonary circulation return oxygenated blood to via what?
To the left atrium
| Via the pulmonary vein
174
How does gas exchange occurs at the alveoli and tissues?
The gas moves from a high partial pressure to a low partial pressure
175
What is the partial pressure of O2 and CO2 in the pulmonary vein?
100mmHg for O2
| 40mmHg for CO2
176
What is the partial pressure of O2 at the tissues?
40mmHg
177
Explain O2 partial pressure at the tissues?
High O2 pressure in blood (100mmHg)
Low partial O2 pressure in tissues (40mmHg)
Moves down pressure gradient
178
Explain CO2 partial pressure at the tissues?
Low CO2 partial pressure in blood (40mmHG)
High CO2 partial pressure in tissues (46mmHg)
CO2 moves into blood down pressure gradient
179
What does A stand for?
Alveolar pressure
180
What does a stand for?
Arterial pressure
181
What does v stand for?
Mixed venous blood
182
What does PaO2 stand for?
Partial pressure of oxygen in arterial blood
183
What does PACO2 stand for?
Partial pressure on carbon dioxide in alveolar air
184
What rules does the diffusion of gas between the alveoli and blood follow?
The rules of simple diffusion
| Moving down its partial pressure gradient
185
What is the rate of gas diffusion directly proportional to?
Partial pressure gradient
Gas solubility
Available surface area
186
What is the rate of gas diffusion inversely proportional to?
The thickness of the membrane
187
Why is the rate of O2 and CO2 diffusion similar even though O2 has a much steeper conc. gradient?
Because CO2 is much more soluble than O2 therefore diffusing faster
188
How thick is the alveolar membrane?
Thin as possible
| Only one cell thick
189
Where are the alveoli directly located by and why?
Blood vessels to decrease the distance needed for gas exchange
190
Why does the alveolar surface have a large surface area?
To allow maximum rate of diffusion of gases
191
How does emphysema affect gas exchange?
Destructs alveoli
| Less surface area for gas exchange
192
How does fibrotic lung disease affect gas exchange?
Thickened alveolar membrane slows gas exchange
193
How does pulmonary oedema affect gas exchange?
Fluid build up increases diffusion distance
194
What causes fibrosis?
Thickened walls of alveoli due to fibrosis tissue
195
What is shunt?
A term used to describe the passage of blood though areas of the lung that are poorly ventilated
196
Is inspiration controlled by smooth or skeletal muscle?
Skeletal
197
What nerves innervate the diaphragm?
Phrenic nerves
198
What controls the innervation of the muscles of breathing?
Pons, medulla
199
From which vertebral levels do the phrenic nerves originate?
C3,4,5
200
Do we have any voluntary control over our breathing?
Yes
201
What modulates our breathing?
Emotion
Voluntary Over ride
Chemical composition of blood
Mechano-sensory input
202
What is the most significant input that changes our breathing?
Chemoreceptor input
203
What are the two types of chemoreceptors?
Central
| Peripheral
204
Where are central chemoreceptors located?
Medulla
205
Where are peripheral chemoreceptors located?
Carotid and aortic
206
What do central chemoreceptors reflect?
CO2
207
What do peripheral chemoreceptors respond to?
Plasma (H+) and PO2
208
What fluid bathes the central nervous system?
CSF
| Cerebral spinal fluid
209
Can the brain and spinal cord tolerate much change to their environment (CSF)?
No
210
What is the blood brain barrier?
A selective barrier that protects the brain by only letting certain things cross
211
Is the blood brain barrier permeable to gas?
Yes
212
Is the blood brain barrier permeable to ions?
No
213
When arterial PCO2 increases what crosses the blood brain barrier?
CO2
214
What effect does an increase in arterial PCO2 have?
Feedback system
| Increases ventilation
215
What effect does a decrease in arterial PCO2 have?
Feedback system
| Slows ventilation rate
216
Below what level does haemoglobin lose a lot of saturation?
60mmHg
217
What happens when PO2 mmHg falls below 60mmHg?
There is a significant increase in ventilation as an attempt to get more O2 into the body
Restoring normal O2
218
Do alveoli have a small or large surface area?
Large
219
Describe the thickness of the membrane at the alveoli?
Thin membrane
220
What is perfusion?
The process of the body delivering blood to a capillary bed in its biological tissue
221
Is blood flow at the base of the lungs high or low and why?
High because arterial pressure exceeds alveolar pressure
222
Is vascular resistance at the base of the lung high or low?
Low
223
Is the blood flow at the apex of the lungs high or low?
Low because arterial pressure is less than alveolar pressure
224
Is vascular resistance at the apex of the lungs high or low?
Higher
225
If ventilation decreases what happens at the capillary bed?
PCO2 increases
PO2 decreases
Blood flowing past those alveoli does not get oxygenated
226
What is shunting?
Dilution of oxygenated blood from better ventilated areas
227
When hypoxia is detected why do blood vessels in the lungs constrict?
To allow less blood to flow to the poorly oxygenated ares
228
What happens to blood vessels in the rest of the body when hypoxia is detected?
They dilate
229
What nerves stimulate the external intercostal muscles?
Intercostal nerves
230
Where is emotion in the brain controlled?
Limbic system
231
Where does a rise in (H+) conc. come from?
CO2
232
If there is increased ventilation is more CO2 blown off or retained?
Blown off
233
If there is decreased ventilation is more CO2 blown off or retained?
Retained
234
Why can't you stop yourself breathing and kill yourself?
Because after you have been knocked unconscious the innate breathing system will kick in and begin breathing again
235
What is ventilation reflexly inhibited by?
Increase in arterial PO2 or a decrease in arterial PCO2
236
When else is respiratory inhibited?
During swallowing to avoid aspiration of food or fluids
237
What is swallowing folloed by?
Expiration
238
Why is swallowing followed by expiration?
To dislodge outwards particles from the region of the glottis
239
What volume of O2 dissolves in 1L of water?
3ml
240
What does haemoglobin increase the carrying capacity of O2 to?
3ml to 200ml per litre
241
What cells is haemoglobin found in?
Red blood cells
242
What would gaseous phase gases travelling in the blood cause?
Bubbles in the blood causing fatal air embolism
243
What is the resting oxygen demand of tissues?
250ml/min
244
What % of O2 is extracted by peripheral tissues at rest?
25%
245
Whats the difference between HbA and HbA2?
Where delta chains replace beta chains
246
Whats the difference between HbA and HbF?
Where gamma chains replace beta chains
247
What is glycosylated Hb associated with?
Glucose
248
Is the glycolysation of Hb reversible?
No it is irreversible
249
What is the major determinant of the degree to which haemoglobin is saturated?
The partial pressure of oxygen in the arterial blood
250
How many subunits is haemoglobin composed of?
4
251
When does oxygen stop entering the plasma?
When all Hb is saturated
252
How much O2 does each litre of systemic arterial blood contain?
200ml
253
At PO2 60mmHg how saturated is haemoglobin?
90%
254
Do HbF and myoglobin have a higher or lower affinity for O2 than HbA?
Higher
255
Does foetal haemoglobin have a higher or lower affinity than the mothers haemoglobin for oxygen?
Higher affinity
256
Why does foetal haemoglobin have a higher affinity for O2?
So that it can acquire and pull in O2 from the mothers blood
257
In anaemia is there any problem with ventilation?
No
258
In anaemia is there any problem with diffusion?
No
259
Even when O2 content is low why can PaO2 be normal?
Because the haemoglobin that is present is saturated
260
What is anaemia?
Defined as the condition where the oxygen carrying capacity of the blood is compromised
261
What factors can affect haemoglobin affinity?
pH
Temperature
CO2
(DPG)
262
How is the affinity of haemoglobin decreased?
Decrease in pH
Increase in temperature
Increase in PCO2
263
How is the affinity of haemoglobin increased?
Increase in pH
Decrease in temperature
Decrease in PCO2
264
What does an increased affinity of haemoglobin cause?
Makes oxygen unloading more difficult
| But aids the collection of oxygen in the pulmonary circulation
265
Is shunt perfused or ventilated?
Perfused but not ventilated
266
Is alveolar space ventilated or perfused?
Ventilated but not perfused
267
What is shunting the opposite to?
Alveolar dead space
268
Where does the majority of perfusion-ventilation mismatch occur?
At the apex of the lung
269
What should the value of perfusion-ventilation ideally be?
1
270
At which level does the trachea bifurcate?
T4
271
Which spinal nerves innervate the phrenic nerve?
C3,4,5 (keep the diaphragm alive)
272
What is hypoxic hypoxia?
This is when PaO2 is below normal
273
What is anaemic hypoxia?
This is when the lungs are in perfect working condition however the carrying capacity of )2 of the blood has been reduced
274
What is circulatory hypoxia?
This is when the heart cannot pump the blood to the tissues or lungs
275
What is metabolic hypoxia?
When oxygen delivery to the tissue does not meet increase demand by cells
276
Describe hypoventilation
Causes CO2 retention
Causes increase in H+ conc
Brings about respiratory acidosis
277
Describe hyperventilation
Blowing off more CO2,
Decreased H+ conc
Brings about respiratory alkalosis
