Lecture 23 - Ventilation Perfusion Relationships Flashcards

1
Q

define acinus

A

single gas exchanging unit (alveolus + pulmonary capillary)

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2
Q

in the ideal lung, what is the relationship between ventilation and perfusion

A

V / Q = 1

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3
Q

Ventilation (V)

A

movement of airflow to and from alveoli

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4
Q

Perfusion (Q)

A

movement of blood to and from alveoli

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5
Q

what is the normal V/Q ratio

A

0.8

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6
Q

what 2 factors affect the gas concentrations in the blood

A
  1. rate of alveolar ventilation
  2. rate of oxygen and carbon dioxide transfer through the respiratory membrane
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7
Q

T/F: carbon dioxide diffuses much faster than oxygen

A

TRUE

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8
Q

VT

A

Tidal volume

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9
Q

describe the relationship of alveolar ventilation to other factors

A

equal to the product of the frequency of tidal per minute and the difference of tidal volume and physiologic dead space

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10
Q

what is a shunt

A

good perfusion (blood to alveoli) but no ventilation (oxygen does not reach alveoli)

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11
Q

what is a dead space

A

good ventilation (oxygen to alveoli) but no perfusion (disrupted blood flow)

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12
Q

in normal anatomy, where does venous blood flow

A

to alveoli for oxygenation and then to the L-side of the heart

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13
Q

The ____ lung gets more ventilation while the ___ gets less

A

dorsal; ventral

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14
Q

what could cause a shunt

A
  1. airway obstruction
  2. pneumonia
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15
Q

what could cause a dead space ventilation

A
  1. pulmonary embolism
  2. cardiogenic shock
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16
Q

what is the V:Q in a shunt

17
Q

What are the 3 types of dead space ventilation

A
  1. anatomic dead space
  2. alveolar dead space
  3. physiologic dead space
18
Q

describe an anatomic dead space

A

conducting airways that do not participate in gas exchange

19
Q

describe an alveolar dead space

A

ventilation to alveoli but no perfusion (blockage or low BP)

20
Q

describe physiologic dead space

A

anatomic + alveolar dead space
(dead space compared to tidal volume)

air intake that cannot be used

21
Q

define venous admixture

A

when less oxygenated blood mixes with oxygenated blood

22
Q

T/F: the amount of O2 and CO2 in the blood is a summary of diffusion

A

FALSE - V/Q efficiency

23
Q

hypoventilation

24
Q

hyperventilation

25
normal PaCO2
40 mmHg
26
norm-oxemia
80-100 mmHg
27
hypoxemia
<60 mmHg
28
what 3 things could cause an increase in V/Q mismatch
1. increase in venous admixture 2. decreased arterial oxygen 3. increase in carbon dioxide
29
what does the alveolar gas equation allow
prediction of amount of oxygen in alveoli
30
what is the alveolar gas equation
PaO2 = PiO2 - (PaCO2/R) PiO2 = 21% atmosphere R = 0.8
31
hypoxic pulmonary vasoconstriction (HPV)
pulmonary vessels constrict in places of low PaO2 and shunt to places with high pressure to decrease mismatching