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CVS > Lung Physiology > Flashcards

Lung Physiology Flashcards

1
Q

At rest at what way through the capillary is Hb fully saturated?

A

25%

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2
Q

What are the constituents of the respiratory pump?

A

Bones, muscle, pleura, peripheral nerves

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3
Q

Which out of expiration and inspiration is passive at rest?

A

expiration

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4
Q

What are the two movements of the ribs?

A

Pump handle, Water handle

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5
Q

What capacity do the pulmonary vessels have at rest

A

30%

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6
Q

Per breath how much dead space is there?

A

175ml - 150 in the trachea and 25 in the capillaries where there are no blood vessels

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7
Q

what does PAC02 stand for?

A

Alveolar carbon dioxide concentration

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8
Q

what does Pa02 stand for?

A

arterial oxygen concentration

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9
Q

what does V.A stand for ?

A

Alveolar Ventilation

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10
Q

What is hypoxic pulmonary constriction?

A

When the pulmonary arteries constrict in regions of low oxygen levels to either supply oxygen to muscles requiring oxygen or to other regions of the lung with better ventilation

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11
Q

How do the lungs act as a buffer for pH concentration?

A

They can remove CO2 which reduces the amount of hydrogen ions and carbonic acid

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12
Q

what is the equation relating to acid base regulation due to the lungs?

A

pH= 6.1x log10([HCO3]/[0.03PCO2])

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13
Q

what is respiratory alkalosis?

A

This is a decrease in PaCO2 which results in n increase in pH due to a mild decrease of HC03. [look at acid base equation]

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14
Q

What does RV stand for ?

A

Residual Volume

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15
Q

what does VC stand for ?

A

vital capacity

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16
Q

what does FRC stand for

A

functional respiratory volume

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17
Q

what does TLC stand for?

A

total lung capacity

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18
Q

what does ERV and IRV stand for?

A

the expiratory/inspiratory reserve volume

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19
Q

What is the FEV1?

A

this is the forced expiratory volume in one second [important to look at for obstructive airway diseases]

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20
Q

How does gas dilution work to measure lung volume?

A

a patient is connected at the end tidal position of the spirometer and it measures all of the air that communicates with the airways by using a closed loop helium setup

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21
Q

how does plethysmography work to measure the lung volume?

A

The patient pants with an open glottis against a closed shutter to produce changes in the box pressure proportionate to the chest. This measures the FRC, ERV, RV, TLC.

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22
Q

What is DLCO?

A

it is an overall measure of the interaction of; alveolar surface, alveolar capillary perfusion, Hb concentration, reaction rate of carbon monoxide

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23
Q

How is DLCO expressed/measured?

A

it is expressed as the uptake of carbon monoxide in millilitres of gas at a standard temp and pressure, dry, per minute, per millilitre of mercury driving pressure of carbon monoxide.

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24
Q

what would be different about a patients FEV1 and FVC if they had pulmonary fibrosis?

A

both be reduced significantly

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25
Q

what would be different about a patients FEV1 and FVC if they had COPD?

A

FEV1 would be reduced but FVC would not.

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26
Q

When abnormal values are acquired what should you check?

A

Look at test quality by looking at the graph. Ensure that the machines were calibrated. Ensure patient age weight and height are entered correctly.

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27
Q

what is the cut off for something being accepted as ‘normal’?

A

Generally anything over 60% of predicted.

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28
Q

what does MEF stand for?

A

Mid expiratory flow - when 75% of the vital capacity is yet to be exhaled.

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29
Q

What is the typical shape for an asthma patients MEF?

A

Scalloped. This is usually a lower value then predicted too.

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30
Q

What reading for Raw will you get for a patient with COPD?

A

Typically high. This is a high airway resistance due to several reasons.

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31
Q

what are the two centres for the control of breathing?

A

Pneumotaxic and the apneustic both located in the pons.

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32
Q

What are the two respiratory groups located in the brain stem?

A

The dorsal respiratory group [DRG].

The ventral respiratory group. [VRG].

33
Q

When is the DRG predominantly active?

A

mainly during inspiration.

34
Q

how does expiration become active?

A

with the recruitment of the muscles of the abdominal wall activity.

35
Q

what percentages of chemoreceptors are central and peripheral?

A

central - 60%

peripheral - 40%

36
Q

How is the brain sensitive to hydrogen ions and bicarbonate ions when they cannot pass the blood brain barrier?

A

CO2 can diffuse across the blood brain barrier and then it reacts with water in the fluid to create bicarbonate ions and hydrogen ions.

37
Q

What things are the carotid and aortic chemoreceptors sensitive to?

A

PaCO2, PaO2, pH

38
Q

Where in the carotid artery are the carotid bodies?

A

they are located at the bifurcation of the common carotid.

39
Q

where are the aortic bodies located?

A

in the ascending aorta.

40
Q

what are the 3 lung receptors called?

A

stretch, J and irritant.

41
Q

What are the first major structural units formed in the embryonic stage of the lung?

A

Angiogenesis, Mucous glands, Cartilage, smooth muscle, cilia.

42
Q

When does vascularisation occur of the lung in the embryo?

A

The canalicular phase, weeks 16-25

43
Q

When does alveolar budding occur during embryology of the lung?

A

Saccular/ Alveolar phase.

25 weeks +

44
Q

Is the lung an important organ to the foetus?

A

No, because the foetus gets it oxygen from the blood supply from the placenta.

45
Q

Is there fluid in the lungs of a foetus and why?

A

Yes there is because there is a high resistance but a low resistance from the placenta. The fluid aids its development

46
Q

How is the first breath taken if fluid is in the lungs?

A

the fluid is squeezed out during the birth procedure.

47
Q

How is surfactant related to Laplaces law that if volumes are different there will be unequal expansion?

A

This relates to alveolar expansion. Alveoli are different sizes so this law states that the biggest alveoli will expand and continue to expand creating unequal expansion. It is surfactants role to reduce surface tensions and stop this from happening.

48
Q

What will happen if no surfactant is released during the first breath?

A

there will be uneven aeration which will result in non-compliant lungs and a loss of lung volume.

49
Q

what is the PiO2?

A

the pressure of inspired oxygen. At atmospheric pressure this is 100KPa x 0.21.

50
Q

What is the relationship between pressure and altitude?

A

As altitude increases pressure decreases in a non-linear relationship.

51
Q

What is PAO2 at sea level? [calculation]

A

PiO2 - PaCO2/R = PAO2

20 - 6/0.8
20-7.5
12.5KPa

52
Q

what is a normal blood pH?

A

7.36-7.44

53
Q

What is a normal PaCO2?

A

4.5-6.0

54
Q

what is a normal PaO2?

A

10.5-13.5

55
Q

At altitude what responses does hypoxia lead to?

A

Hyperventilation which;

increases minute ventilation, lowers PaCO2, Alkalosis initially, Tachycardia.

56
Q

What is the guidance cut off for a persons oxygen saturation where they need supplementary oxygen?

A

Anything less than 92%.

57
Q

How does the change in atmosphere underwater compare to that of altitude?

A

the change in pressure under water is much greater than the change with altitude.

58
Q

What is boyles law?

A

P1V1 = P2V2 At a constant temp the absolute pressure of a fixed mass of gas is inversely proportional to its volume.

59
Q

What happens to the gas pressures during apnoea diving?

A

they all increase as the pressure increases and are forced into the capillaries.

60
Q

What causes an apnoea divers desire to breathe?

A

the gradual build up of CO2.

61
Q

What are the 3 reflexes of diving?

A

Apnoea
Bradycardia
Peripheral vasoconstrictor

62
Q

What is daltons law?

A

That the total pressure exerted by gas mixes is equal to the sum of the pressures that would be exerted by each gases if it was alone present and occupied the total volume.

63
Q

What are the two pulmonary vascular circulations?

A

the pulmonary blood circulation - 100% from right ventricle.
The bronchial circulation - 2% from left ventricle.

64
Q

What is the time of red cell transition?

A

the time is roughly 5 seconds.

65
Q

What is the combined surface area for gas exchange in a healthy individual in metres?

A

50 - 100 m^2.

66
Q

What are the differences between the pulmonary and systemic arteries?

A

Pulmonary has thinner walls and minor muscle surrounding the lumen. Also there is no need for redistribution.

67
Q

What pressure does pulmonary circulation run at in reference to systemic?

A

about 1/6th of systemic circulation.

68
Q

What happens to resistance when the radius of the ‘lumen’ increases?

A

it decreases at a much larger rate. This is due to poiseuilles law the resistance will change at 4 power rate.

69
Q

What is mPAP?

A

mean pulmonary arterial pressure.

70
Q

what is PVR?

A

pulmonary vascular resistance.

71
Q

what is PAWP?

A

pulmonary arterial wedge pressure [left atrial pressure]

72
Q

What does pressure across pulmonary circulation equal?

A

mPAP - left atrial pressure x pulmonary vascular resistance.

73
Q

What 4 main things cause hypoxia?

A

Hypoventilation
Diffusion impairment
Shunting
V/Q mismatch

74
Q

What is shunting?

A

blockages in the blood vessels resulting in a V/Q mismatch.. Full blockages can cause alveolar dead space.

75
Q

What is meant by diffusion impairment?

A

Anything that reduces the amount of diffusion of oxygen into the red blood cells.
Pulmonary oedema, Anaemia, Interstitial fibrosis.

76
Q

Whats the difference between type 2 and type 1 respiratory failure?

A

Type 1 is a reduced oxygen levels.

Type 2 is a reduced oxygen level and an increase in carbon dioxide level.

77
Q

What is hypoxic pulmonary vasoconstriction?

A

When there is low PaO2 there is a reduction in perfusion to the lung. This is because there is not oxygen at the lung for the blood to collect so it is diverted to other parts of the body such as peripheral muscles that need oxygen.

78
Q

Why can Deep Vein thrombosis cause an issue for the lung?

A

quite often the clots in the legs move up the vena cava and lodge in the right ventricle. This has a huge impact on pulmonary circulation.

CVS (6 decks)

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