RS Lecture 3 and 4 - Ventilation & Gas Transport and Exchange Flashcards Preview

LSS 1 - Thorax anatomy, Respiratory and Circulatory system > RS Lecture 3 and 4 - Ventilation & Gas Transport and Exchange > Flashcards

Flashcards in RS Lecture 3 and 4 - Ventilation & Gas Transport and Exchange Deck (100)
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1
Q

What are normothermic ex vivo ventilated perfused lungs?

A

No restriction to movement as no chest wall and expand freely in all directions

2
Q

What is minute ventilation?

A

Volume of air expired in one minute or per minute

3
Q

What is Resp rate?

A

Frequency of breathing per minute

4
Q

What is Alveolar ventilation?

A

Volume of air reaching the resp zone

5
Q

What is respiration?

A

Process of generating ATP either with an excess of O2 (aerobic) or a shortfall (anaerobic)

6
Q

What is anatomical dead space?

A

Capacity of airways incapable of undertaking gas exchange

7
Q

What is alveolar dead space?

A

Capacity of airways that should be able to undertake gas exchange but cannot

8
Q

What is physiological dead space?

A

Equivalent to the sum of alveolar and anatomical dead space

9
Q

What is hypoventilation?

A

Deficient ventilation of the lungs - unable to meet metabolic demand > Acidosis (^CO2)

10
Q

What is hyperventilation?

A

Excessive ventilation of lungs atop of metabolic demands > Alkalosis (decreased CO2)

11
Q

What is hyperpnoea?

A

^ depth of breathing to meet metabolic demand

12
Q

What is hypopnea?

A

Decreased depth of breathing - inadequate to meet metabolic demand

13
Q

What is apnoea?

A

Cessation of breathing

14
Q

What is dyspnoea?

A

Difficulty in breathing

15
Q

What is bradypnoea?

A

Abnormally slow breathing rate

16
Q

What is tachypnoea?

A

Abnormally fast breathing rate

17
Q

What is orthopnea?

A

Positional difficulty in breathing (mainly when lying down)

18
Q

What are the 2 components of the chest wall?

A

Bone, muscle, fibrous tissue AND lungs

19
Q

What way does the rib cage recoil?

A

Outwards

20
Q

What way do the lungs recoil?

A

Inwards

21
Q

What is the functional residual capacity?

A

At the end of tidal expiration: Elastic recoil of lungs inwards = ER of ribs outwards

22
Q

What is needed to remove the FRC equilibrium?

A

Muscular effort to push equilibrium to one way/another

23
Q

What is the volume of the pleural cavity?

A

Fixed and contains protein-rich pleural fluid

24
Q

What is the pressure of the pleural cavity?

A

Negative

25
Q

What happens when we do a full inspiration (in terms of walls/pressure)?

A

Chest wall expands and pulls diaphragm down and lungs need to be pulled with it - negative pressure in pleural cavity pulls lungs with chest wall

26
Q

What can happen to disturb the connection between lungs and chest wall?

A

Lungs will deflate - caused by puncture in chest wall/lung so pleura will fill with air or blood, so elastic recoil of lung takes over and causes collapse

27
Q

Whats the difference between time taken in development of haemo and pneumothorax?

A

Haemo overtaking f elastic lung recoil occurs much slower

28
Q

What is tidal breathing?

A

The amount of inspiration and expiration that meets metabolic demand - usually nasal

29
Q

How is the Functional Residual Capacity measured?

A

Trough of a tidal breath to 0

30
Q

Why can you not fully empty the lungs?

A

Surfactant in alveoli prevents them from sticking together and not reopening

31
Q

What is the residual volume?

A

The volume that remains in the lungs after full expiration

32
Q

What are the four main volumes of air?

A

Tidal, Inspiratory reserve, Expiratory reserve and Reserve (can be combined to capacities)

33
Q

What is TLC?

A

Full volume of lungs - TV+IRV+ERV+RV

34
Q

What is vital capacity?

A

How much air is in the range we’re able to inspire/expire - TLC-RV

35
Q

What is functional residual capacity?

A

Vol of air in the lungs when recoil in ribs and lungs are in equilibrium - ERV+RV

36
Q

What is inspiratory capacity?

A

How much air can be taken in on top of FRC - TV+IRV

37
Q

What factors affect lung volumes and capacities?

A

Body size (HEIGHT, shape), sex, fitness, disease (pulm or neuro), age

38
Q

What drives flow?

A

Pressure - from high to low

39
Q

What unit is used when talking about lung volumes?

A

cmH2O

40
Q

When does positive pressure breathing occur?

A

Atmospheric pressure is increased above Alveolar pressure such as in Ventilation, CPR

41
Q

When does negative pressure breathing occur?

A

Alveolar pressure is reduced below atmosphere pressure such as in healthy breathing

42
Q

How do you work out transmural pressures?

A

P-inside - P-outside

43
Q

What leads to inspiration (pressures)?

A

A negative transrespiratory pressure

44
Q

What leads to expiration (pressures)?

A

Positive transmural pressure - recoil of lungs expires, but air is pushed in

45
Q

What is transmural pressure?

A

Pressure across a tissue/several tissues

46
Q

What is a transpulmonary pressure?

A

Difference between alveolar and intrapleural pressure

47
Q

What is the transrespiratory pressure?

A

IMPORTANT - tells if airflow in/out of lung

48
Q

What is intrapleural pressure?

A

Pleura stretches outwards, alveoli inwards so pressure is negative

49
Q

Ventilation cycle:

A

Start: No transpulmonary pressure

50
Q

What is the conducting zone?

A

16 generations with no gas exchange and is equivalent to anatomical dead space (150mL)

51
Q

What is the respiratory zone?

A

7 generations -> gas exchange (350mL) and is equivalent to alveolar ventilation

52
Q

What is non-perfused parenchyma?

A

Alveoli without blood supply -> no gas exchange (0mL), equivalent to alveolar dead space

53
Q

What 2 reversible procedures can increase and decrease a persons dead space?

A

Increase: Ventilation tube Decrease: Tracheostomy (avoiding first part)

54
Q

What is Poiseuille’s law?

A

Resistance = 8*viscosity of gas*length of tube / pi*radius^4

55
Q

What are the ventilation mechanics?

A

Diaphragm does a pulling force in one direction (syringe). Intercostal respiratory muscles are an upwards and outwards swinging force (bucket handle)

56
Q

What is the chest-wall relationship?

A

Intact lung has a sigmoid shaped lung (greater pressures to achieve same change in volume when the lungs are at higher/lower volumes)

57
Q

What is a volume-time curve?

A

FVC is amount of air pushed out at force; FEV1 is how rapid someone can remove air in lungs, index of airways resistance

58
Q

How can you tell if patient has obstructive pulmonary disease from a volume-time curve?

A

FEV1 is much lower related to FVC; FVC is lower

59
Q

How can you tell if patient has restrictive pulmonary disease from a volume-time curve?

A

FVC is lower; FEV1 much higher and FEV1:FVC is high, nearing 1

60
Q

What are the 3 ventilation tests that are done to test lung function?

A

Volume-time curve, peak expiratory flow, flow volume loop

61
Q

What is peak expiratory flow test?

A

Patient exhales as fast as possible from TLC, with value measured against ‘normal’ values

62
Q

What is the flow-volume loop?

A

Maximum inspiratory and expiratory curves are main important and you can read VC, TV, ERV, IRV from the graph

63
Q

How does the flow-volume loop reflect mild and severe obstructive and restrictive diseases?

A

MOD: Operate at higher volumes, [caving] as when emptying of smaller airways is difficult, so greater muscular effort (same with SOD just worse) RD: lower volumes

64
Q

How does flow-volume loop reflect variable extra/intrathoracic obstruction and fixed airway obstructions?

A

VEO: Only blunted on inspiratory portion -> sucking the mass

VIO: Only blunted on expiratory portion -> pushing mass into airway when breathing out

FAO: Unable to deviate so only be able to breathe in small amounts

65
Q

Which of the following combinations would be greatest in a healthy adult? A: TV + ERV + RV + IC B: TLC + TV + RV + IC C: IRV + VC + TV + TLC D: ERV + VC + IC + RV

A

C

66
Q

Which word describes short of breath? A: Apnoeic B: Orthopnoeic C: Hypopnoeic D: Dyspnoeic E: Bradypnoeic

A

D

67
Q
  1. Which is the least likely feature of a COPD patients flow volume curve? A: Blunted inspiratory curve B: Caving C: Low peak flow rate D: Reduced vital capacity
A

A

68
Q

Distinguish between pulmonary and alveolar ventilation

A

Pulmonary is air ventilating the entire airway; alveolar is air ventilating respiratory surfaces

69
Q

What are the 5 Gas laws? (Dalton Flicks Henry’s Boil Cheerfully)

A

Dalton mixes gases, Fick’s gases diffuse proportionally, Henry’s gases dissolve proportionally, Boyle’s volume is inversely proportional to pressure, Charles’ volume is proportional to temperature

70
Q

What are the relative proportion of gases in room air, O2 therapy, house fire and high altitude?

A
71
Q

How do the inspiratory gases change from the air to the respiratory airways?

A

Air is warmed, humidified, slowed and mixed

72
Q

What is haemoglobin and what are they made up of?

A

Consists of Fe2+ at centre of 4 polypeptides, with adults usually having 2 alpha and 2 beta chains (some 2 alpha and 2 delta chains - HbA2) and foetal Hb containing 2 alpha and 2 gamma chains

73
Q

How does O2 bind to HbA?

A

At rest, Hb has a low affinity for O2 and when the first molecule binds it undergoes a conformational change, so there is a higher affinity for the second and higher for the 3rd molecule of O2 -> greater competition for each spot -> affinity for the 4th is 300x greater than for the first -> COOPERATIVITY phenomenon

74
Q

How does HbA change when O2 attaches to it?

A

There is a change in the protein structure forming a binding site for 2,3-DPG, which promotes O2 unloading by shifting Hb into the tense state

75
Q

What type of protein is Hb?

A

Allosteric protein

76
Q

What is metHb?

A

When Fe2+ is further oxidised to Fe3+, where it cannot bind to O2, with metHbaemia causing functional anaemia

77
Q

What causes metHb?

A

Nitrites oxidise Hb into ferric MetHb or can be genetic

78
Q

What is P50?

A

Partial pressure at which Hb is 50% saturated

79
Q

What happens to P50 when the O2 dissociation curve shifts to the right and what causes this?

A

For any given pressure there is less O2 bound, so releasing O2 more easily: DECREASES AFFINITY -> ^ temperature, acidosis, hypercapnia, ^2,3-DPG -> occur when exercising

80
Q

What happens to P50 when the O2 dissociation curve shifts to the left and what causes this?

A

INCREASES AFFINITY caused by decreased temperature, alkalosis, hypocapnia, decreased 2,3-DPG

81
Q

What happens to P50 when the O2 dissociation curve shifts down and what causes this?

A

Anaemia -> causes impaired O2-carrying capacity - P50 stays the same

82
Q

What happens to P50 when the O2 dissociation curve shifts up and what causes this?

A

Polycythaemia -> increased O2-carrying capacity - P50 stays the same

83
Q

What happens to P50 when the O2 dissociation curve shifts down and to the left and what causes this?

A

Hb has greater affinity for CO than O2, so occupies binding sites and changes the cooperativity -> so increases affinity, so P50 is very low

84
Q

What is the O2-dissociation curve of HbF?

A

Has greater affinity for O2, to extract the oxygen from the mother’s HbA in the placenta

85
Q

What is the O2 dissociation curve of myoglobin?

A

Much much greater affinity that HbA to extract O2 from circulating blood and store it for when necessary - hyperbolic curve

86
Q

How does O2 transport occur from the alveoli to the capillary?

A

HbA (RBC) with 75% saturation arrive at alveoli and O2 diffuses from alveoli to capillary down the conc grad as the PAO2 is larger than PaO2, and since SVO2 is 75%, the last O2 adds on with ease, with the SaO2 becoming 100% and PO2=PAO2=13.5kPa

87
Q

How is O2 transported in the blood?

A

O2 moves down the concentration gradient into the cells, diffusing across -> used for respiration and then the rest of the Hb continues round the body and to the heart then repeats the cycle again

88
Q

Why is the saturation of the blood in the pulmonary vein that reaches the heart not 100% saturated?

A

Blood from the bronchiole arteries drain into the pulmonary vein just before entering the heart, so the blood goes down to 97% saturation

89
Q

How much O2 is transported in the blood?

A

2% O2 is carried in the plasma, and 98% in the Hb -> amount of dissolved O2 is inadequate for life, but is used for O2 unloading

90
Q

What is the oxygen flux in the capillary in respiring tissues?

A

Amount of O2 lost -> 250mL O2min^-1

91
Q

How is CO2 transported in the blood?

A

CO2 crosses membranes faster and binds to water forming H2CO3, forming a buffer to maintain the pH -> venous blood is slightly more acidic than arteriolar blood

92
Q

What is the CO2 flux in the capillary of respiring tissues?

A

200mL CO2min^-1, leaving the cells

93
Q

What happens to CO2 in the RBC?

A

CO2 enters the RBC, where it binds with water to form H2CO3 (carbonic anhydrase), which then dissociates and HCO3- is exchanged with Cl- via AE1 transporter [Chloride shift to maintain membrane potential], H2O enters the RBC as well -> CO2 bind to Hb, to the amine end to form carbaminoHb -> excess H+ in RBC are bound by Hb (has some H+ acceptor chains) to maintain the pH, until they are needed to be released

94
Q

What are the 3 roles of Hb?

A

O2 transport, CO2 transport and buffering inside of the RBC

95
Q

How is CO2 transported in the arterial vs venous blood?

A

Not much difference in quantity of CO2 but how it is transported varies

96
Q

What is the pulmonary transit time?

A

0.75s (RBC in touch with pulm. membrane), gases are very soluble, so move across very rapidly, and when exercising you are still able to get efficient gas exchange -> takes 0.25s for O2 to diffuse and less for CO2 because it is more soluble

97
Q

What is ventilation perfusion mismatching?

A

Due to gravity, blood follows path of least resistance, so there is more perfusion in the lower lobes of the lung -> at rest apical ones are basically closed. Ventilation is also higher at basal than apical due to gravity as the lung has a net weight, which makes the intrapleural pressure higher at the bottom, making it easier to ventilate at the bottom than the top

NB: Perfusion is impacted much more than ventilation

98
Q

What is the equation for CO?

A

CO=SV*HR mL/min

99
Q

What is the alveolar ventilation equation?

A

AV= (TV-dead space)*respiratory frequency mL/min

100
Q

How do you calculate ventilation perfusion ratio?

A

V/Q ratio=Alveolar ventilation/CO with no units

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