Ventilation and GE Flashcards
(87 cards)
1
Q
What is minute ventilation?
A
Volume of air expired in one minute.
2
Q
What is respiratory rate?
A
Frequency of breathing per minute
3
Q
What is alveolar ventilation? (Valv)
A
Volume of air reaching the respiratory zone per minute.
4
Q
What is respiration?
A
Process of generating ATP either with an excess of oxygen (aerobic) and a shortfall (anaerobic)
5
Q
What is anatomical dead space?
A
The capacity of the airways incapable of undertaking GE.
6
Q
What is alveolar dead space?
A
Capacity of the airways that should be able to undertake GE, but can’t.
E.g. hypoperfused alveoli
7
Q
What is physiological dead space?
A
Equivalent to the sum of alveolar and anatomical dead space
8
Q
What is hypoventilation?
A
Deficient ventilation of the lungs; unable to meet metabolic demand (increase pO2 - acidosis)
9
Q
What is hyperventilation?
A
Excessive ventilation of the lungs atop of metabolic demand (results in reduced pCO2 - alkalosis)
10
Q
What is hyperpnoea?
A
Increased depth of breathing to meet metabolic demand.
11
Q
What is hypopnoea?
A
Decreased depth of breathing (inadequate to meet metabolic demand)
12
Q
What is apnoea?
A
Cessation of breathing (no air movement)
13
Q
What is dyspnoea?
A
Difficulty in breathing
14
Q
What is bradypnoea?
A
Abnormally slow breathing rate
15
Q
What is tachypnoea?
A
Abnormally fast breathing rate
16
Q
What is orthopnoea?
A
Positional difficulty in breathing (when lying down)
17
Q
Are volumes discrete sections on the graph?
A
Yes
18
Q
What are capacities on the graph?
A
Sum of 2 or more volumes
19
Q
How can you calculate inspiratory capacity?
A
Inspiratory reserve volume + tidal volume
20
Q
How can you calculate vital capacity?
A
IRV + TV + ERV
OR
Inspiratory capacity + ERV
21
Q
How can you calculate functional residual capacity (FRC)?
A
ERV + residual volume
22
Q
Define TV
A
Volume of air that occupies the lungs during periods of quiet breathing (500ml).
23
Q
Define ERV
A
Volume of air that can forcefully be exhaled succeeding normal tidal expiration (1200ml)
24
Q
Define IRV
A
Produced from deep inhalation, past tidal inspiration. Is additional volume that is drawn into lungs through forced inspiration.
25
Define RV
Volume present in lungs upon maximum exhalation. The residual assist with breathing ability by preventing alveoli collapse.
26
How can you calculate minute ventilation?
MV = Tidal volume (L)(0.5L) x Breathing frequency (breaths/min)(12 bpm) = 6 L/min
27
How can you calculate alveolar ventilation?
(TV - Dead space) x Breathing frequency
E.g. (0.5-0.15) x 12 = 4.2 L/min
28
Do cartilaginous C-shaped rings throughout the trachea and bronchioles participate in GE?
No - It is anatomical dead space
29
What factors affect lung volumes and capacities?
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Sex (male, female)
Body size (height, shape)
Fitness (innate, training)
Age (chronological, physical)
Disease (pulmonary, neurological)
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30
How many generations does the conducting zone contain? Volume?
16 generations; No GE
| Typically 150mL in adults at FRC.
31
What is the conducting zone equivalent to?
Anatomical dead space
32
How many generations does the respiratory zone have? Volume?
7 generations
GE takes place
Typically 350mL in adults.
33
What is air reaching respiratory zone equivalent to?
Air reaching here is equivalent to alveolar ventilation.
34
What are non-perfused parenchyma?
Alveoli without a blood supply
No GE
Typically 0mL in adults
Called alveolar dead space.
35
How can you increase dead space reversibly?
Intubation
| Anaesthetic circuit snorkelling
36
How can you decrease dead space reversibly?
Tracheostomy
| Cricothyrotomy
37
Explain the chest wall relationship.
The chest wall has a tendency to spring outwards and the lung has tendency to recoil inwards.
These forces are in equilibrium at end-tidal expiration (FRC).
Chest recoil=lung recoil
38
Explain how changes in the chest wall relationship results in inspiration.
Inspiratory muscle effort + chest recoil > lung recoil
39
Explain how changes in the chest wall relationship results in expiration.
Chest recoil < Expiratory muscle effort + lung recoil
40
What membrane surround the lungs?
Visceral pleural membrane
41
What is the inner surface of the chest wall covered by?
Parietal pleural membrane
42
What is the pleural cavity?
The gap between pleural membranes which is a fixed volume and contains protein-rich fluid.
43
What is it called when a persons lung has intrapleural bleeding?
Haemothorax
44
What causes pneumothorax?
Perforated chest wall.
| Could also be causes by a punctured lung.
45
Explain negative pressure breathing.
Alveolar pressure is reduced below atmospheric pressure hence air moves into lungs.
46
Explain positive pressure breathing.
Atmospheric pressure is increased above alveolar pressure hence air still enters lung.
47
Give an example of negative pressure breathing.
Normal breathing
48
Give examples of positive pressure breathing.
Mechanical ventilation
CPR
Resuscitation (mouth to mouth)
49
How is a transmural pressure calculated?
Pressure inside - pressure outside
50
What will a negative transrespiratory pressure lead to?
Inspiration
51
What will a positive transmural pressure lead to?
Expiration
52
How do you calculate trans thoracic pressure (PTT)?
PTT = Pleural pressure - atmospheric pressure
E.g. Ppl - Patm = -5 - 0 = -5 cmH2O
53
How do you calculate transpulmonary pressure (PTP)?
PTP = Alveolar pressure - pleural pressure
E.g. Palv - Ppl = 0--5 = 5 cmH2O
54
How do you calculate transrespiratory pressure (PRS)?
PRS = Alveolar pressure - atmospheric pressure
E.g. Palv - Patm = 0 - 0 = 0 cmH2O
55
Explain the effect of the diaphragm.
Effect is like a syringe.
| A pulling force in one direction.
56
Explain the effect of respiratory muscles excluding the diaphragm.
Their effect is like a bucket hand.
| An upwards and outwards swinging force.
57
What is Dalton's law?
Pressure of a gas mixture is equal to the sum of the partial pressures (p) of gases in that mixture.
58
What is Fick's law?
Molecules diffuse from regions of high concentration to low concentration at a rate proportional to the concentration gradient, the exchange SA and the diffusion capacity of the gas and inversely proportional to the thickness of the exchange surface.
59
What is Henry's law?
At a constant temperature, the volume of a given gas that dissolves in a given type and volume of liquid is directly proportional to the partial pressure of that gas equilibrium with that liquid.
60
What is Boyle's law?
At a constant temperature, the volume of a gas is inversely proportional to the pressure of that gas.
61
What is Charles's law?
At a constant pressure, the volume of a gas is proportional to the temperature of that gas.
62
Which is gas is the most abundant in the air at sea level?
N2 ~78%
| then its oxygen at ~21%, Argon then CO2
63
What has your patient been breathing if their pCO and pCO2 have increased, but pO2 has decreased?
Smoke (house fire)
64
What happens to air as it passes down the respiratory tree?
Warmed, humidified, slowed and mixed
65
Which part of the respiratory tree has the highest pCO2?
Respiratory zone (alveoli)
66
How can you calculate oxygen solubility (Cd - dissolved content)?
Cd gas = alpha gas x Partial pressure of gas
E.g. Cd O2 = alpha O2 x Partial pressure of Oxygen
Cd O2 = 0.024 x 13.5 = 0.32 mL/dL = 16 mL/min
67
What is total O2 delivery at rest?
16 mL/min
68
What do Hb monomers consist of?
Ferrous iron (Fe2+) at centre of a tetrapyrole porphyrin ring connected to a protein chain (-globin); covalently bonded at the proximal histamine residue.
69
What type of protein is Hb?
Allosteric
70
Explain what cooperativity is in terms of Hb.
Binding of one O2 to the Hb molecule increases affinity of that Hb molecule to other O2 molecules at its other 3 binding sites.
71
What can cause right shift on the oxygen dissociation curve?
Increased temperature
Acidosis (Bohr Effect)
Hypercapnia
Increased 2,3 DPG
72
What can cause left shift on the oxygen dissociation curve?
Decreased temperature
Alkalosis
Hypocapnia
Decreased 2,3-DPG
73
What condition causes a downwards shift in the oxygen dissociation curve?
Anaemia - impaired oxygen carrying capacity.
74
What condition causes a upwards shift in the oxygen dissociation curve?
Polycythaemia - increased oxygen carrying capacity
75
What effect does increased carboxyHb and CO have on the shape of the oxygen dissociation curve?
Downwards and leftwards.
| Decreased capacity, but an increased affinity for O2.
76
What effect does ^HbF have on the oxygen dissociation curve?
Greater affinity than HbA therefore left shift.
77
What effect does ^ myoglobin have on the oxygen dissociation curve?
Myoglobin has a much greater affinity than HbA for oxygen hence curve shifts almost all the way to the left.
78
Outline oxygen loading.
Mixed venous blood =75% oxygen saturation, oxygen is not required during periods of low demand. There is an established partial pressure potential gradient (Alveolar partial pressure > Venous partial pressure (O2)). Thus, oxygen diffuses into the interstitial space through into the capillaries, binding onto associated haem groups within erythrocytes, cooperatively.
79
Outline oxygen unloading.
Actively respiring aerobic tissue will have a low partial pressure associated with it due to increased oxygen consumption to supply oxidative phosphorylation, facilitating the production of ATP. The reduction in partial pressure, and generation of partial pressure gradient between the arriving oxygen capillaries and tissue > Counter current mechanism.
80
What is oxygen flux?
The amount of oxygen delivered to peripheral tissue per minute.
81
Outline what happens to carbon dioxide once it is taken up by red blood cells
It binds to H2O and with the enzyme carbonic anhydrase, it forms carbonic acid
Carbonic acid dissociates into a proton and bicarbonate anion.
The bicarbonate anion is transported out of the RBC and a Cl- is transported in, to maintain resting membrane potential - AE1 transporter
CO2 also binds to Hb at the amine end to form carbaminoHb.
82
Why is there a decrease in partial pressure of oxygen in the blood unloaded at the tissues from when it was loaded in the lungs?
The venous bronchial circulation dumps blood with less oxygen into it and this dilutes the blood.
83
Why is the oxygen flux not the same as the carbon dioxide flux?
Water is produced as a by-product of the respiration occurring in the cells that blood unloads to. So carbon dioxide flux is less than oxygen flux.
84
Is the gas exchange time for carbon dioxide less or more than that for oxygen at the alveoli?
Less
85
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Which of the following factors would shift the oxygen dissociation curve to the right?:
Supplemental oxygen therapy
Blood doping in cyclists
30 mins sunbathing in 30 degree weather
Unconctrolled type 1 diabetes
```
Uncontrolled T1DM
86
What is the pulmonary transit time (PTT)?
Time it takes for a molecule to cross the GE surface (0.75s), oxygen can equilibrate within length of time.
87
What causes PTT to decrease?
Cardiac output increases during exercise leading to a decrease in PTT (Improves ability to increase oxygen saturation of haemoglobin, oxygen loading is faster).
