30 Gas Transport and Ventilation Flashcards

1
Q

Gas Law–The pressure of a gas =?

A

the sum of the partial pressure of all its constitutes

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2
Q

4 important gases in the body?

A

N2, O2, CO2, H2O

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3
Q

In the air, the atmospheric pressure is approximately equal to the sum of which two pressures?

A

N2 and O2

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4
Q

Atmosphere is approximately % N and % O?

A

79% N and 21% O

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5
Q

Atmospheric pressure at sea level mmHg?

A

760 mmHg

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6
Q

Is the PCO2 greater within the alveoli or in room air?

A

Much greater in alveoli

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7
Q

What is Henry’s Law?

A

Quantity of dissolved gas= partial pressure x solubility coefficient

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8
Q

What are the 3 forms carbon dioxide is transferred in the blood?

A

dissolved (5%), as bicarbonate (77%), and as carbamino compounds (18%)

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9
Q

What drives the diffusion of gases?

A

a pressure or concentration gradient

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10
Q

Does CO2 or O2 have a greater solubility?

A

CO2

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11
Q

Is the CO2 bound to hemoglobin bond strong?

A

No its weak.

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12
Q

What do red blood cells contain that facilitate combination of Co2 and water?

A

carbonic anhydrase

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13
Q

CO2 and water combine to form?

A

carbonic acid—dissociates to proton and bicarbonate

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14
Q

Does the bicarbonate stay in the RBC where it is formed?

A

no, it diffuses out because of concentration differences

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15
Q

What diffuses into RBC in order to maintain electroneutrality when bicarb diffuses out?

A

chloride—hence the chloride shift

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16
Q

What is the volume of gas inspired or expired with each breath?

A

Tidal Volume

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17
Q

What is the minute ventilation?

A

tidal volume x respiratory rate

18
Q

What is the portion of minute ventilation that does not participate in gas exchange?

A

dead space ventilation

19
Q

What are the two types of dead space ventilation?

A

anatomical and physiological

20
Q

What is the portion of minute ventilation that does participate in gas exchange called?

A

Alveolar ventilation

21
Q

What is alveolar ventilation + dead space ventilation?

A

minute ventilation

22
Q

What 2 things result in the level of CO2 in the alveolus?

A
  1. How much CO2 is delivered.

2. How much CO2 is eliminated

23
Q

Alveolar PO2 is determined by what 2 factors?

A

Alveolar ventilation and oxygen consumption

24
Q

What type of motion is it when each molecule moves with random?

A

Brownian Motion

25
Q

Ficks law of diffusion takes in account which three factors?

A
  1. driving pressure
  2. properties of gas
  3. properties of the membrane
26
Q

How long is each blood cell in contact with alveolus?

A

.75 seconds– only needs .25 seconds to equilibrate

27
Q

Do thick alveolar walls indicate diffusion limitation in the case of hypoxemia?

A

No- real mechanism is mismatch of ventilation and perfusion

28
Q

O2 content of blood and cardiac output combined is equal to?

A

O2 delivery

29
Q

What is the shape of the dissociation curve for hemoglobin and oxygen?

A

sigmoid shaped due to cooperative binding

30
Q

What are the two pools of oxygen being carried in the blood?

A

Hb bound O2 (98%) + dissolved O2 (2%)

31
Q

Is it more popular to judge blood oxygenation by saturation or PO2?

A

saturation

32
Q

What occurs if O2 content falls and tissue oxygen delivery cannot be maintained?

A

Tissue hypoxia

33
Q

What are the 2 most popular reasons O2 content falls?

A
  1. low arterial 02 saturation

2. low hemoglobin concentration

34
Q

Is the diffusion distance in tissues much greater than in lung?

A

yes

35
Q

What provides a storage tank for oxygen in the muscle?

A

myoglobin

36
Q

What increases release of oxygen in the tissues (right shift of curve)?

A

lowered pH, increased pCO2, increased temp, and increase in 2,3-DPG

37
Q

When does 2,3 DPG get released more?

A

accumulation of glycolytic intermediates

38
Q

what is true rate limiting step of O2 Transport?

A

diffusion distance

39
Q

what is the most effective way of increasing oxygen delivery to a given tissue?

A

recruiting or construction of additional capillaries

40
Q

Gases with a similar solubility in blood and diffusion barrier are said to be what?

A

perfusion limited

41
Q

Gases with very different solubility in blood and a diffusion barrier are said to be?

A

diffusion limited

42
Q

True or False: Both oxygen and carbon dioxide are diffusion-limited in tissues

A

true