Respiratory Physiology Flashcards
(155 cards)
1
Q
What are the functions of the respiratory system?
A
1.) gas exchange - oxygen/carbon dioxide
2.) acid base balance - regulation of body pH
3.) protection from infection
4.) communication via speech
2
Q
Why is gas exchange so important?
A
Need to produce energy
3
Q
How does it produce energy?
A
Do this by “burning” oxygen, produce carbon dioxide as a waste product
4
Q
What does the ability of tissues to transform fuel stored as chemical energy to physical energy depend on?
A
The integration of the CVS and respiratory systems to deliver fuel to the active cells within the tissues, and remove waste products
5
Q
What is cellular/internal respiration?
A
Biochemical process that releases energy from glucose either via Glycolysis or Oxidative Phosphorylation
6
Q
What does oxidative phosphorylation depend on and require?
A
Depends on external respiration and requires oxygen
7
Q
What is external respiration?
A
Movement of gases between the air and the body’s cells, via both the respiratory and cardiovascular systems
8
Q
What is Exchange I?
A
Between atmosphere and lung
9
Q
What is Exchange II?
A
Between lung and blood
10
Q
What is Exchange III?
A
Between blood and cells
11
Q
What is special about the pulmonary circulation?
A
It is opposite to the systemic circulation in function and terminology
12
Q
What does the pulmonary circulation do?
A
It delivers CO2 (to the lungs) and collects O2 (from the lungs) while the systemic circulation delivers O2 to peripheral tissues and collects CO2
13
Q
What does the pulmonary artery/pulmonary vein carry?
A
Pulmonary artery - deoxygenated blood
Pulmonary vein - oxygenated blood
14
Q
What is the net volume of gas exchanged in the lungs/tissues per unit time?
A
250ml/min O2
200ml/min CO2
15
Q
What is the normal respiration rate?
A
12-18 breaths/min at rest
Can reach 40-45 at max (exercising capacity in adults)
16
Q
What are the main features of the respiratory system?
A
- nose
- pharynx
- epiglottis
- larynx
- trachea
- bronchus
- lung
17
Q
What does the nose do in the respiratory system?
A
Air enters your body through your nose, where cilia and mucus trap particles and warm and moisten the air
18
Q
What does the pharynx do in the respiratory system?
A
From your nose air moves down into the pharynx, or throat, which is shared with the digestive system
19
Q
What does the epiglottis do in the respiratory system?
A
This small flap of tissue folds over the trachea and prevents food from entering it when you swallow
20
Q
What does the larynx do in the respiratory system?
A
The larynx, or voice box, contains your vocal chords, which vibrate to produce sound
21
Q
What does the trachea do in the respiratory system?
A
From the pharynx air moves down toward the lungs through your trachea, the trachea is made up of stiff rings of cartilage that support and protect it
22
Q
What do the bronchus do in the respiratory system?
A
Air moves from the trachea into the right and left bronchi, which lead inside the lungs
23
Q
What do the lungs do in the respiratory system?
A
The main organs of respiration, their soft, spongy texture is due to the many thousands of tiny hollow sacs that compose them
24
Q
What does the upper respiratory tract contain?
A
- pharynx
- nasal cavity
- vocal chords
- esophagus
- tongue
- larynx
25
What does the lower respiratory tract contain?
- trachea
- right/left lung
- right/left bronchus
- diaphragm
26
What are the different lobes separated by on each lung?
Right lung
superior lobe -> horizontal fissure -> middle lobe -> oblique fissure -> inferior lobe
Left lung
superior lobe -> oblique fissure -> inferior lobe
27
How many times does each bronchus branch?
24 times (primary, secondary, tertiary, bronchioles)
28
What does patency mean?
The condition of being open or unobstructed
29
How is the patency of airway maintained?
C-shaped rings of cartilage
30
How is patency maintained in bronchioles?
No cartilage, maintained by physical forces in thorax
31
What is the alveoli?
Point of gas exchange
32
What are the alveoli covered in?
Elastic fibres
33
What do elastic fibres do?
Allow inflation of the alveoli during inspiration, and the energy that is stored in the elastic fibres as they expand is released during expiration to force air out of the alveoli
34
What do type I cells do?
Gas exchange
35
What do type II cells do?
Synthesize surfactant
36
What is the air in the airways called that doesn’t participate in gas exchange?
Anatomical dead space
37
What is the average total volume of the lungs?
6 litres
38
What is the normal volume for respiration?
2.3 litres —> 2.8 litres
39
What is tidal volume?
The volume of air breathed in and out of the lungs at each breath
40
What is the functional residual capacity?
Expiratory reserve volume + Residual volume
41
What is the inspiratory reserve volume?
The maximum volume of air which can be drawn into the lungs at the end of a normal inspiration (roughly 3 litres)
42
What is the expiratory reserve volume?
The maximum volume of air which can be expelled from the lungs at the end of a normal expiration (roughly 1-1.1 litres)
43
What is the dead space volume?
Roughly 150ml
44
What is residual volume?
The volume of gas in the lungs at the end of a maximal expiration
45
What is the vital capacity?
Tidal volume + Inspiratory reserve volume + Expiratory reserve volume
46
What is the total lung capacity?
Vital capacity + residual volume
47
What is the inspiratory capacity?
Tidal volume + Inspiratory reserve volume
48
How many pleural cavities is there?
2 (right and left)
49
What are the two types of membrane?
Parietal pleura and Visceral pleura
50
Where is the visceral pleural membrane found?
Adjacent to the lungs superior surface (visceral = generic term for organ)
51
Where is the parietal pleural membrane found?
Exterior surface of the pleural sac
52
What is a pneumothorax?
The seal between the membranes and chest wall is broken, so the chest wall continues to expand and the lung collapses to its unstretched size due to air entering the pleural cavity
53
What does Boyle’s Law state?
The pressure entered by a gas is inversely proportional to its volume
54
What does Dalton’s Law state?
The total pressure of a gas mixture is the sum of the pressures of the individual gases
55
What does Charles Law state?
The volume occupied by a gas is directly related to the absolute temperature
56
What does Henry’s Law state?
The amount of gas dissolved in a liquid is determined by the pressure of the gas and its solubility in the liquid
57
What muscles does inspiration use?
External intercostal muscles and the diaphragm, under heavy respiratory load the stemocleidomastoid and scalene muscles are used
58
What muscles does expiration use?
Passive at rest, but uses internal intercostal and abdominal muscles during severe respiratory load
59
What does the diaphragm do during inspiration?
Contracts to allow thoracic volume to increase
60
What do the external intercostal muscles do? and what do the internal intercostal muscles do?
Raise the rib cage upwards and outwards, and the internal intercostals do the opposite
61
What is intra-thoracic (alveolar) pressure?
Pressure inside the thoracic cavity, essentially pressure inside the lungs, may be negative or positive compared to atmospheric pressure
62
What is intra-pleural pressure?
Pressure inside the pleural cavity, typically negative compared to atmospheric pressure (in healthy lungs at least!)
63
What is trans pulmonary pressure?
Difference between alveolar pressure and intra-pleural pressure, almost always positive because intra-pleural pressure is negative (in healthy cases)
64
What is surfactant?
Detergent like fluid produced by Type II Alveolar cells
65
What does surfactant do?
- reduces surface tension on alveolar surface membrane thus reducing tendency for alveoli to collapse
- increases lung compliance (distensibility)
- reduces lung’s tendency to recoil
- makes work of breathing earlier
- is more effective in small alveoli than large alveoli because surfactant molecules come closer together and are therefore more concentrated
66
Where does surface tension occur?
Where ever there is an air-water interface and refers to the attraction between water molecules
67
When does surfactant production start/finish?
starts —> 25 weeks gestation
finishes —> 36 weeks gestation
68
What is surfactant production stimulated by?
Thyroid hormones and cortisol (increase towards the end of pregnancy)
69
What do premature babies commonly suffer from?
Infant Respiratory Distress Syndrome (IRDS)
70
What is compliance?
Change in volume relative to change in pressure
i.e. how much does volume change for any given change in pressure
71
What does compliance represent?
Stretchability of the lungs (not the elasticity)
72
What does high/low compliance mean respectively?
high - large increase in lung volume for small decrease in intra-pleural (ip) pressure
low - small increase in lung volume for large decrease in ip pressure
73
Are healthy lungs highly compliant? or low?
High, but some unhealthy lungs can also be highly compliant
74
What is pulmonary (minute) ventilation?
Total air movement into/out of lungs (relatively insignificant in functional terms)
75
What is alveolar ventilation?
Fresh air getting to alveoli and therefore available for gas exchange (functionally much more significant!)
76
What is pulmonary ventilation and alveolar ventilation measured in?
L/min
77
What is hypoventilation?
Decreasing tidal volume and breathing rapidly
78
What is partial pressure?
The pressure of a gas in a mixture of gases is equivalent to the percentage of that particular gas in the entire mixture multiplied by the pressure of the whole gaseous mixture
79
What percentage of the air we breathe is O2?
21%
80
What is the value of normal ventilation?
4.2 L/min
81
Where is the greatest alveolar ventilation found?
At the base of the lung
82
What is normal alveolar partial pressure of O2?
100mmHg or 13.3 kPa
83
What is the normal alveolar partial pressure of CO2?
40mmHg or 5.3 kPa
84
How is bronchial circulation supplied?
Via the bronchial arteries
85
What branch delivers nutritive blood supply to the lungs?
Bronchial circulation
86
What branch is responsible for gas exchange in blood?
Pulmonary circulation
87
Pulmonary circulation a has _____ flow, ______ pressure system
High flow, low pressure system
88
What does A, a and v stand for?
A = alveolar
a = atrial blood
v = mixed venous blood (e.g. in pulmonary artery)
89
What does PaO2 and PACO2 mean?
PaO2 = partial pressure of oxygen in arterial blood
PACO2 = partial pressure of carbon dioxide in alveolar air
90
The rate of diffusion across the membrane is: ???? (5 points)
1.) directly proportional to the partial pressure gradient
2.) directly proportional to gas solubility
3.) directly proportional to the available surface area
4.) inversely proportional to the thickness of the membrane
5.) most rapid over short distances
91
What are the values of PO2 and PCO2 in alveoli and systemic arterial blood?
PO2 = 100mmHg
PCO2 = 40mmHg
92
What are the values of PO2 and PCO2 in pulmonary arterial blood and at tissues?
PO2 = 40mmHg
PCO2 = 46mmHg
93
What is emphysema?
Destruction of alveoli which reduces surface area for gas exchange
94
What is fibrotic lung disease?
Thickened alveolar membrane which slows gas exchange, loss of lung compliance may decrease alveolar ventilation
95
What is pulmonary oedema?
Fluid in interstitial space that increases diffusion distance, arterial PCO2 may be normal due to higher CO2 solubility in water
96
What is asthma?
Increased airway resistance that decreases ventilation
97
What’s the difference between obstructive and restrictive lung disease?
Obstructive —> obstruction of air flow, especially on expiration
Restrictive —> restriction of lung expansion
98
What are examples of obstructive lung disorders?
- asthma
- COPD (chronic obstructive pulmonary disease)
- chronic bronchitis (inflammation of the bronchi)
- emphysema (destruction of the alveoli, loss of elasticity)
99
What are examples of restrictive lung disorders?
- fibrosis
- infant respiratory distress syndrome (insufficient surfactant production)
- oedema
- pneumothorax
100
What is spirometery?
A technique commonly used to measure lung function, measurements can be classed as static or dynamic
101
What’s the difference between static and dynamic?
Static - where the only consideration made is the volume exhaled
Dynamic - where the time taken to exhale a certain volume is what is being measured
102
What volumes/capacities can be measured by spirometery?
- Tidal volume
- Inspiratory reserve volume
- Expiratory reserve volume
- Inspiratory capacity
- Vital capacity
103
What is the FEV1/FVC lung function test for?
Start establishing a diagnosis of different conditions
104
What does FEV1 refer to?
Forced expiratory volume in 1 second (fit, healthy, young adult males: 4.0L)
105
What does FVC refer to?
Forced vital capacity (fit, healthy, young adult males: 5.0L)
106
What is the FEV1/FVC for a fit, healthy, young adult male?
80% (4L:5L)
107
What happens to the ratio of FEV1/FVC in obstructive disorders?
Both FEV1 and FVC fall but FEV more so, so ratio is reduced
108
What happens to the ratio of FEV1/FVC in restrictive disorders?
Both FEV1 and FVC fall so ratio remains normal, or may even increase, despite severe compromise of function
109
Why does it require a greater change in pressure from functional residual capacity to reach a particular lung volume during inspiration, than to maintain that volume during expiration?
1.) overcome lung inertia during inspiration
2.) overcome surface tension during inspiration
3.) during expiration compression of the airways means more pressure is required for air to flow along them
110
Do obstructive diseases increase the work of inspiration or expiration?
Expiration
111
Do restrictive diseases increase the work of inspiration or expiration?
Inspiration
112
What is the ventilation:perfusion ratio if its perfectly matched?
1
113
What is the ventilation
<1
114
What is the ventilation>perfusion ratio if its mismatch 2 (apex)?
>1
115
What percentage of the height of healthy lung performs well in matching blood and air?
Over 75%
116
Where does the majority of mismatch take place?
The apex
117
What does “Shunt” mean?
perfusion > ventilation
opposite of alveolar dead space
alveolar PO2 falls (pulmonary vasoconstriction), PCO2 rises (bronchial dilation)
118
What is “Alveolar Dead Space”?
ventilation > perfusion (autoregulation)
opposite of shunt
PO2 rises (pulmonary vasodilation), PCO2 falls (bronchial constriction)
119
What is anatomical dead space?
Refers to air in the conducting zone of the respiratory tract unable to participate in gas exchange as walls of airways in this region (nasal cavities, trachea, bronchi and upper bronchioles) are too thick.
120
What is physiologic dead space?
Alveolar Dead Space + Anatomical Dead Space
121
What does RSA (respiratory sinus arrhythmia) do?
Ensures ventilation:perfusion ratio remains close to 1 during breath cycle (vagal activity decreases on inspiration and decreases on expiration)
122
What are the two forms that oxygen travels in the blood?
In solution in plasma and bound to haemoglobin protein in red blood cells
123
What volume of oxygen dissolves per litre of plasma?
3ml
124
How much oxygen is there per litre in the whole blood?
200ml (197ml of which is bound to haemoglobin in red blood cells)
125
How much CO2 is stored in haemoglobin/transported in solution in plasma?
23% stored
77% transported
126
What percentage of arterial O2 is extracted by peripheral tissues at rest?
25%
127
What is the composition of a haemoglobin molecule?
4 haeme groups, each of which contains one Fe2+, which each bind to one O2 molecule
128
How many oxygen molecules can bind to one haemoglobin?
4
129
What is anaemia?
Any condition where the oxygen carrying capacity of the blood is compromised
e.g. iron deficiency, haemorrhage, vit B12 deficiency
130
What happens to PO2 in anaemia?
Nothing, PO2 is normal despite total blood O2 content being low
131
When does affinity of haemoglobin for O2 change?
In response to certain chemical factors (pH, PCO2, temp, DPG)
132
What way does a decrease in pH move the oxygen-haemoglobin curve?
To the right
133
What way does an increase in pH move the oxygen-haemoglobin curve?
To the left
134
What way does a decrease in PCO2 move the oxygen-haemoglobin curve?
To the left
135
What way does an increase in PCO2 move the oxygen-haemoglobin curve?
To the right
136
What way does a decrease in temp move the oxygen-haemoglobin curve?
To the left
137
What way does an increase in temp move the oxygen-haemoglobin curve?
To the right
138
What way does no 2,3-DPG move the oxygen-haemoglobin curve?
To the left
139
What way does added 2,3-DPG move the oxygen-haemoglobin curve?
To the right
140
How is CO2 transported?
Diffuses from the tissues into the blood
141
What is CO2 used for?
7% dissolved in plasma and erythrocytes, 23% combines in the erythrocytes with deoxyhaemoglobin to form carbamino compounds, and 70% combines in the erythrocytes with water to form carbonic acid (which dissociates to yield bicarbonate and H+ ions)
142
What does PaO2 refer to, and what is it determined by?
Refers purely to O2 in solution in the plasma and is determined by O2 solubility and the partial pressure of O2 in the gaseous phase that is driving O2 into solution
143
How much oxygen (roughly) is there in each litre of systemic arterial blood?
200ml of oxygen
144
How many ml of O2 binds to each gram of haemoglobin?
1.34ml
145
What is another type of oxygen carrier molecule and where is it found?
Myoglobin, found exclusively in cardiac and skeletal muscle
146
What are the 5 types of hypoxia?
1.) hypoxaemic hypoxia
2.) anaemia hypoxia
3.) stagnant hypoxia
4.) histotoxic hypoxia
5.) metabolic hypoxia
147
What is hypoxaemic hypoxia?
- most common
- reduction in O2 diffusion at lungs either due to decreased PO2atmos or tissue pathology
148
What is anaemia hypoxia?
Reduction in O2 carrying capacity of blood due to anaemia (red blood cell loss/iron deficiency)
149
What is stagnant hypoxia?
Heart disease results in inefficient pumping of blood to lungs/around the body
150
What is histotoxic hypoxia?
Poisoning prevents cells utilising oxygen deleivered to them e.g. carbon monoxide/cyanide
151
What is metabolic hypoxia?
Oxygen delivery to the tissues does not meet increased oxygen demand by cells
152
What nerve stimulates the diaphragm?
Phrenic nerve
153
What nerve stimulates the external intercostal muscles5
Intercostal nerves
154
What keeps the diaphragm alive?
C3, C4, C5
155
What is the rhythm of respiratory centres modulated by?
1.) emotion (via limbic system in the brain)
2.) voluntary over-ride (via higher centres in the brain)
3.) mechano-sensory input from the thorax (e.g. stretch reflex)
4.) chemical composition of the blood (PCO2, PO2 and pH) - detected by chemoreceptors
