resp-5 gas properties Flashcards

1
Q

what drives diffusion

A

different partial pressures

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2
Q

what is daltons law

A

total pressure is the sum of individual pressures (partial pressures)

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3
Q

what ranges is oxygen Po2

A

150-160mmHg

21%

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4
Q

ficks law of diffusion–> proportionalities

A

diffusion is proportional to area, diffusion constant, (P1-p2) and inverse to thickness

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5
Q

what is the diffusion constant

A

the amount of gas transferred between the alveoli and the blood/unit time

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6
Q

what is the diffusion constant proportional to

A

gas solubility

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7
Q

does co2 or o2 have a higher diffusion constant

A

co2

more soluble, same molecular weight

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8
Q

what entails diffusion constant

A

proportional to solubility, inversely proportional to molecular weight

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9
Q

henrys law

A

the amount of gas dissolved in a liquid is directly proportional to the partial pressure of gas in which the liquid is in equilibrium

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10
Q

what determines concentration of a gas in liquid (2 factors)

A

their solubility and their partial pressure

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11
Q

why is Po2 in air> po2 in alveoli

A

humidification of air in resp (more water, relative percentage of other molecules decreases)
loss O2 to blood diffusion (hemoglobin)
mixing inspired air with alveolar air (functional residual capacity)

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12
Q

what determines alveolar po2 and pco2

A

Po2 and PCO2 in atm
alveolar ventilation
metabolic rate (more you use, more you take)
perfusion

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13
Q

increasing alveolar ventilation does what do alveolar po2 and pco2

A

increase alveolar po2 and decrease alveolar pco2

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14
Q

increasing metabolic rate does what do alveolar po2 and pco2

A

decrease alveolar po2 and increase alveolar pco2

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15
Q

what determines arterial levels of gases

A

partial pressure of gas in alveoli

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16
Q

when does getting the first bit of o2 happen (in healthy person)

A

in the first third of the capillary system

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17
Q

what is cardiac output

A

volume of blood pumped by the heart per minute

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18
Q

does systemic or pulmonary system have higher pressure

A

systemic higher pressure

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19
Q

why is pulmonary low pressure system

A

only pumps blood to top of lung, shorter and wider vessels

20
Q

why is the pulmonary high compliance vessels

A

lots of arterioles with low restine tone
thin walls and little smooth muscle can accept large amount of blood
can dilate in increase to pressure

21
Q

when would alveolar capillaries collaps

A

if capillary pressure falls below
alveolar pressure, the capillaries close off, diverting blood to other pulmonary
capillary beds with higher pressures

22
Q

what is the ventilation/perfusion ratio (V/Q0

A

balance
between LUNG ventilation (O2 ATM→ALVEOLI / CO2
ALVEOLI→ATM) and LUNG perfusion (O2 ALVEOLI → BLOOD
/CO2 BLOOD → ALVEOLI).

23
Q

what is a major factor that the ventilation/pefusion ratio affects

A

the alveolar and arterial elvels of Po2 and Pco2

24
Q

more ventilation does what to po2 and pco2

A

more closely alveolar po2 and pco2 will approach their respective valuesof the insipired air

25
Q

more perfusion does what to po2 and pco2

A

the more closely the composition of

local alveolar air will approach that of mixed-venous blood.

26
Q

what does high V/Q ratio mean

A

high ventilation

low perfusion

27
Q

what causes a high V/Q ratio

A

alveolar/physiologic dead space

regions where air reaching them is not taken up by blood (underperfused, like from blood clot)

28
Q

what is ventilation

A

the air that reaches the alveoli

29
Q

what is perfusion

A

the blood that reaches the alveoli

30
Q

What are relative po2 and pco2 in high V/Q ratio

A

high po2 low pco2

similarto air

31
Q

what is anatomical dead space

A

volume of conducting airways that do not participate in gas exchange

32
Q

what is alveolar dead space

A

regions of lung with high V/Q ratios. Regions that are relatively over
ventilated (UNDERPERFUSED) so that a portion of the fresh air reaching these alveoli
can not be taken up by the blood.

33
Q

what could cause high V/Q ratio

A

blood clot, preventing perfusion

34
Q

what could cause a low V/Q ratio

A

airway obstruction

35
Q

What are relative po2 and pco2 in low V/Q ratio

A

low po2 high pco2, no fresh air coming in and cant remove co2

36
Q

what is a shunt

A

portion of venous blood that doesnt get oxygenated and goes back to arterial blood

37
Q

what does the local V/Q ratio determine

A

local alveolar Po2 and Pco2

38
Q

where is perfusion greatest in the lungs and why

A

base of lungs

more weight at bottom and more air goes there

39
Q

what does perfusion depend on

A

gravity and posture

40
Q

po2 co2 relationship at top of lungs

A

high po2

low pco2

41
Q

po2 co2 relationship at bottom of lungs

A

low po2

high pco2

42
Q

does blood flow or ventilation increase more as you go lower in the lungs

A

blood flow increases more dramatically

43
Q

how does V/Q change in top and bottom of lungs

A

top of lungs has high V/Q

bottom of lungs has low V/Q

44
Q

what is pulmonary hypoxic vasoconstriction

A

low O2 to capillary, vasoconstrict to increase flow to an alveoli that works

45
Q

what happens when theres decreased blood flow to a region of the lungs

A

bronchoconstriction (less co2 carried to the alveoli) so there is decreased air flow and it is rediverted to a better area

46
Q

where is circuclation is there the most similar amount of pco2 and po2

A

venous

47
Q

what determines alveolar po2 (3)

A

PO2 of atmospheric air
the rate of alveolar ventilation
the rate of total-body oxygen consumption