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Systems 1 Part 2 > Ventilation Perfusion > Flashcards

Ventilation Perfusion Flashcards

1
Q

compare circulation pressures

A

pulmonary lower than systemic

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2
Q

how does lower pulmonary pressures affect pulmonary capillary walls?

A

allows it to be thinner and have less smooth muscle

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3
Q

significance of thinner pulmonary capillary walls

A

facilitates gas exchange

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4
Q

blood from the vena cava enters the right atrium at – pressure

A

low

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5
Q

compare the atrial pressures

A

similar

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6
Q

pulmonary vascular compliance is high because it takes the –

A

full cardiac output at all times

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7
Q

blood from the pulmonary veins enter the left atrium at – pressure

A

low

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8
Q

pressure increases rapidly through the –

A

LV to systemic circulation

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9
Q

pressure in RA

A

central venous pressure

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10
Q

pressures in the chambers increases from

A

RA < LA < RV < LV

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11
Q

systemic vascular resistance

A

(mean arterial pressure - central venous pressure) / CO

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12
Q

pulmonary vascular resistance

A

(mean pulmonary arterial pressure - left atrial pressure) / CO

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13
Q

pulmonary left atrial pressure is estimated by

A

pulmonary capillary wedge pressure

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14
Q

mean aortic pressure

A

systemic mean arterial pressure

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15
Q

Pulmonary vascular resistance is modulated by the body in response to changes in –

A

blood flow

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16
Q

during exercise, – increases

A

CO and bp

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17
Q

how does the body compensate for increased CO and bp

A

relaxing vascular tone

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18
Q

recruitment

A

opening closed vessels

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19
Q

how do lungs maintain a relatively constant PA pressure

A

recruitment and distension

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20
Q

T/F: vascular tone is moderated by chemical features

A

true

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21
Q

vasoconstriction from –, serotonin, histamine, thromboxane A2, endothelin

A

hypoxia

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22
Q

vasodilation from NO, – Ca2+ channel blockers, prostacyclin

A

PDE inhibitors

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23
Q

oxygen consumption is based on – sex, height, weight

A

age

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24
Q

oxygen consumption can be directly measured using –

A

exhaled breath analysis

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25
In practice, we take a blood gas from the pulmonary artery and estimate the oxygen consumption, back-calculating the cardiac output from these estimates.
Fick's principle
26
what is Kf?
membrane permeability to water in edema/min/mmHg
27
microvasculature circulation is also characterized by its permeability to --
circulating proteins
28
If the membrane was freely permeable (sigma = 0) then the interstitial protein concentration would --
equal plasma concentration
29
why causes the non-uniform distribution of blood flow across the lung?
gravity
30
when does blood flow distribution change?
exercise and postural change
31
ventilation is high at --
top
32
perfusion is high at --
bottom
33
upright lung: apex has lowest blood flow and highest --
ventilation/alveolar pressure
34
pressures in zone 1
alveolar P > capillary P > venous P
35
in zone 1, alveolar P exceeds capillary P so it squashes the capillaries which results in --
impeded blood flow and gas exchange
36
we may see zone 1 in -- where mean airway pressure (alveolar P) are raised and overcome perfusion P creating alveolar dead space
positive pressure ventilation
37
pressure in zone 2
capillary P > alveolar P > venous P
38
pressures in zone 3
capillary P > venous P > alveolar P
39
in zone 3, blood pressure may exceed alveolar pressure so blood flow is determined by
A-v difference
40
zones in supine position
no zone 1, very small zone 2, mostly zone 3
41
normal ventilation of gas exchange
4 L/min
42
normal cardiac out put of blood flow
5 L/min
43
why does PO2 fall from 150 to 100 at lungs: PO2 of alveolar gas is determined by inspired air, removal of O2 by pulmonary capillary blood and --
replacement with fresh gas by alveolar ventilation (breath to breath basis)
44
what determines the rate of removal of O2 from lungs?
O2 consumption of tissue (doesn't vary much during resting)
45
primary determinant of PO2
alveolar ventilation
46
when systemic blood reaches capillaries, O2 diffuses into cells and mitochondria where PO2 is --
much lower
47
hypoventilation
breathe slower or less deeply
48
same perfusion but decreased ventilation
hypoventilation
49
causes of hypoventilation
CNS depression (medications), respiratory muscle weakness, neuromuscular disease, obesity, chest wall mechanics
50
what happens to CO2 and O2 in alveolar hypoventilation
CO2 increases and O2 decreases (same O2 if given supplemental oxygen)
51
diffusion impairment the problem occurs at --
alveolar-capillary interface
52
blood-gas barrier is -- in diffusion impairment
thickened
53
diffusion impairment = thickened muscular vasculature or --
scarred alveoli
54
in diffusion impairment, the amount of gas at alveoli is --
the same
55
in diffusion impairment, the amount of gas at capillary drops due to --
metabolism
56
T/F: diffusion impairment doesn't often cause hypoxemia at rest but can be marked during exercise
true
57
normal blood flow but low ventilation
shunt
58
arterial PaO2 is -- than alveolar PAO2 in shunting
lower
59
shunts can occur in -- areas of lung
collapsed
60
shunts can occur where blood flow passes thru lung without --
touching alveoli
61
shunt can also occur due to mixing of --
venous blood and pulmonary venous return
62
the -- shunt the less response to 100% supplied oxygen
more
63
should hypoxemia be abolished if patient is given 100% oxygen?
no
64
shunting does not affect PCO2 as much because --
chemoreceptors detect high PaCO2 and increase minute ventilation
65
T/F: blood vessels push blood away from poor ventilated areas
true
66
dead space
normal ventilation and no perfusion
67
why is air left in conducting airways?
CO2 for buffering warm air trap particulates humidify air before it reaches alveoli
68
why do we warm air to body temp?
enhance O2 uptake
69
No ventilation and normal perfusion: what happens to O2 and CO2
O2 equilibrates and CO2 rises
70
in long term, no ventilation would lead to a -- alveolus with atelectasis
collapsed
71
no perfusion and normal ventilation: what happens to O2 and CO2
O2 rises and CO2 falls through washing out of alveolus
72
changes in V/Q are met with -- responses
rapid
73
under-ventilation (reduced PAO2) --> reflex
vasoconstriction and perfusion to well ventilated areas
74
under-perfusion (reduced PACO2) --> reflex
bronchoconstriction to well perfused areas

Systems 1 Part 2 (27 decks)

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