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BRS 6: Cardiovascular And Respiratory Medicine > 6.8: Ventilation & gas exchange > Flashcards

6.8: Ventilation & gas exchange Flashcards

(76 cards)

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1
Q

What are lung volumes

A

Discrete sections of the graph and don’t overlap

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2
Q

Capacities are

A

Sum of two or more volumes

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3
Q

Minute ventilation is

A

Volume of air expired in one minute or per minute

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4
Q

Respiratory rate is

A

The frequency of breathing per minute

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5
Q

Calculation for minute ventilation (L/min)

A

Tidal volume(L) x breathing frequency (breaths/min)

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6
Q

Definition of Alveolar ventilation is

A

Gas entering and leaving the alveoli

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7
Q

Calculation of alveolar ventilation (L/min)

A

[Tidal volume (L) - dead space (L)] x breathing frequency (breaths/min)

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8
Q

5 factors affecting lung volumes and capacities

A

Body size
Sex
Fitness
Disease
Age

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9
Q

Definition of dead space

A

Volume of air that doesn’t participate in gas exchange

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10
Q

What is the chest wall relationship

A

Chest wall has a tendency to spring outwards and the lung has a tendency to recoil inwards

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11
Q

What do pressure gradients drive

A

Flow

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12
Q

Example of negative pressure breathing

A

Normal breathing

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13
Q

Pulmonary ventilation is

A

Ventilating entire airways

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14
Q

Alveolar ventilation is

A

Ventilating alveoli

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15
Q

The pieural cavity is a

A

Partial vaccume

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16
Q

Example of positive pressure breathing

A

Ventilation / CPR

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17
Q

What does maximum ventilation involve

A

Full inspiratory muscle recruitment

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18
Q

Daltons law

A

Pressure of a gas mixture is equal to the sum of the partial pressures of gases in that mixture

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19
Q

Ficks law

A

Molecules diffuse from regions of high concentration to low concentration at a rate proportional to the concentration gradient, the exchange surface area and the diffusion capacity of the gas, and inversely proportional to the thickness of the exchange surface

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20
Q

Henry’s law

A

At a constant temperature, amount of a given gas that dissolves in a given type and volume of liquid is directly proportional to the partial pressure of that gas in equilibrium with that liquid

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21
Q

Boyles law

A

At a constant temperature, the volume of a gas is inversely proportional to the pressure of that gas

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22
Q

Charles’ law

A

At a constant pressure, the volume of a gas is proportional to the temperature of that gas

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23
Q

Tachypnoae is

A

Abnormally fast breathing rate

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24
Q

Hyperventilation is

A

Excessive ventilation of the lungs atop of metabolic demand (results in reduced PCO2 - alkalosis)

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25
Difference between hyperventilation and tachypnoea
Decrease in CO2 in hyperventilation and increase in pH
26
Why is there a residual volume
Allows lungs to hold structure to prevent collapsing Functions to keep alveoli open even after max expiration
27
Average minute ventilation of a 70kg healthy male
6L/min
28
What is alveolar dead space
Sum of volumes of alveoli which have little or no blood flowing through adjacent pulmonary capillaries
29
2 main areas of dead space found in bronchi
Conducting zone Non-perfused parenchyma
30
What volume can the conducting zone typically carry in and out for adults at FRC (functional residual capacity)
150ml
31
Can gas exchange occur in the respiratory zone?
Yes Air reaching here is equivalent to alveolar ventilation
32
In adults, how much air can the respiratory zone carry in and out?
350ml
33
Parenchyma is
The functional tissue of an organ as distinguished from the connective and supportive tissue
34
Calculation for physiological dead space
Anatomical + alveolar dead space
35
How to reversibly increase the amount of dead space?
Intubation Anything above mouth would be dead space as gas exch cannot occur
36
How to reversibly decrease amount of dead space?
Tracheostomy / cricothyrocotomy Reduced amount of air passing through conducting zone
37
Why are the lung-chest forces at equilibrium at FRC
Chest recoil = lung recoil Where rib cage naturally recoils outwards and the lungs naturally recoil inwards
38
During inspiratory muscle effort, which is higher, chest or lung recoil?
Chest recoil
39
What process follows as lung recoil is higher than chest recoil ?
Expiration
40
What membrane surrounds the lungs?
Visceral pleural membrane
41
What membrane covers the inner surface of the chest wall
Parietal pleural membrane
42
What is the pleural cavity?
Gap between the pleural membranes which is a fixed volume
43
What does the pleural cavity contain
Protein-rich pleural membrane
44
What is haemothorax
Intrapleural bleeding reduces ability to ventilate
45
What occurs when you have a perforated chest wall or punctured lung?
Lung will collapse on itself as it recoils into preferred position due to leakage of pleural cavity, Difficulty ventilating
46
How does negative pressure breathing occur
Diaphragm pulled down and rib cage pulled out, reducing alveolar pressure below at,spheric so air flow into lungs
47
How does positive pressure breathing occur
Pressure in atmosphere higher than alveolar pressure, air forced out of lungs down pressure gradient
48
3 examples of positive pressure breathing
CPR CPAP- continuous positive airway pressure Mechanical ventilation
49
Why is there negative pleural pressure?
Rib cage naturally recoiling outwards whereas lungs recoil inwards, creating negative pressure in pleural cavity
50
What is transmural pressure?
Refers to the pressure inside relative to outside of a compartment
51
What does negative transrespiratory pressure lead to?
Inspiration
52
What does positive transrespiratory pressure lead to?
Expiration
53
Calculation for transrespiratory system pressure
P(alveolar) - P(atmospheric)
54
What happens to the muscles during inspiration
Diaphragm contracts, creating pulling force in one direction External intercostal muscles contract, pulling rib cage in an upwards and outwards direction
55
How does the composition of air breathed in change when a patient is on oxygen therapy?
Increase in oxygen partial pressure Rest stay the same
56
How does the composition of air being breathed in change when a patient is in a house fire?
Breathe in smoke: Decrease in oxygen partial pressure Increase in carbon dioxide partial pressure Increase in carbon monoxide partial pressure
57
How does composition of air breathed in change when a person is at high altitude?
Composition does not change but the volume of each gas being inhaled decreases
58
How much oxygen is needed by your body at rest
250ml/min
59
Describe the process of haemoglobin cooperativity?
Once an oxygen molecule binds to Hb, structure of Hb is altered so another oxygen molecule is more likely to bind and this continues until all four binding sites have been occupied
60
What role does 2,3-DPG play in the role of haemoglobin
Metabolic product so it is found at sites where there is more respiration occurring and therefore a higher demand of oxygen Once more oxygen molecules have bound to the Hb molecule, 2,3-DPG is more likely to bind to the Hb and this facilitates oxygen unloading
61
What type of protein is haemoglobin
Allosteric protein
62
5 conditions where there’s a right shift of oxygen dissociation curve
Incr. temperature Acidosis Bohr effect Hypercapnia - build up of CO2 in bloodstream, affects people with COPD Incr. 2,3-DPG (during excersise)
63
4 conditions where there is a left shift of oxygen dissociation curve
Decr. Temperature Alkalosis Hypocapnia Decreased 2,3-DPG
64
In what condition is there an upward shift of oxygen dissociation curve
Polycythaemia - incr. oxygen carrying capacity due to more RBCs
65
What conditions cause a downward shift of oxygen dissociation curve
Anaemia - impaired O2 carrying capacity
66
What type of shift does Carbon monoxide cause in oxygen dissociation curve
Downward and left Decreased capacity as oxygen cannot bind to spaces occupied by CO Increased affinity for CO so less unloading
67
What type of shift does Foetal Hb show in oxygen dissociation curve
Left shift Greater affinity than adult HbA to extract oxygen from mothers blood
68
What type of shift does myoglobin show in oxygen dissociation curve
Far left shift Breather affinity than adult HbA to extract oxygen from circulating blood and store it
69
Why is there a decrease in partial pressure of O2 in blood unloaded at tissues from when it was loaded in the lungs?
Venous bronchial circulation dumps blood with less O2 into it, diluting blood
70
What is oxygen flux
Change in oxygen content in blood after it has unloaded oxygen to a respiring cell
71
Outline what happens to CO2 once it’s taken up by RBCs
Binds to H2O with enzyme carbonic anydrase, forming carbonic acid Acid dissociates into a proton and bicarbonate anion Bicarbonate anion transported out of RBC and Cl- transported in, to maintain resting membrane potential - AE1 CO2 also binds to Hb at amine end to form carbaminohaemoglobin
72
What makes Hb a good buffer in RBCs
Binds to protons from when carbonic acid dissociates and enables pH stability
73
Why is O2 flux not the same as CO2 flux
Water produced as by-product of respiration occurring in cells that blood unloads to CO2 flux is less than O2 flux
74
CO2 gas exchange time compared to O2 at alveoli
Lower than O2
75
How does uncontrolled type 1 diabetes affect oxygen dissociation curve
Shifts to the right
76
How does increased tidal volume affect concentration of dissolved oxygen in the blood
Increases concentration

BRS 6: Cardiovascular And Respiratory Medicine (12 decks)

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