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EXCI 357 Pulmonary Physiology > 3. Physical Principles of Gas Exchanges; Diffusion of Oxygen and Carbon Dioxide Through Respiratory Membrane > Flashcards

3. Physical Principles of Gas Exchanges; Diffusion of Oxygen and Carbon Dioxide Through Respiratory Membrane Flashcards

1
Q

Once alveoli are ventilated with fresh air, next step in respiratory process is _____ of ____ from _____ into ______ ______ and diffusion of______ in opposite direction

A 
diffusion
O2
Alvioli 
Pulmanary Blood
CO2
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2
Q

 Diffusion = ______motion of molecules

A

Random

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3
Q 
Gases involved in respiratory physiology are?
a. Free to move 
b. Bound to each other
c. Responsible for the partial pressures?
d. Dissolved gasses in the the blood 
e A & C
f. ACD
g. bdc
A

e. free to move and responsible for the partial pressures

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4
Q

Is energy need for diffusion to occur? If so how is it provided?

A

yes; kinetic motion of molecules themselves

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5
Q

Complete the following sentence regarding the properties of molecular basis of gas diffusion: ____ movement at ___ velocities until collision; then _____ in other direction until other collision

A

Linear,
HIGH
bounce away

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6
Q

molecules move ____ and _____

A

fast

randomly

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7
Q

Diffusion rate is directly proportional to _______ _____

A

concentration gradient

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8
Q

Pressure of a gas acting on surfaces of airways and alveoli is directly proportional to ________ ____molecules. Is true for? Single gas pressure or multiple?

A

the concentration of the gas molecules

true for single gasses

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9
Q

Pressure caused by each gas alone is called?

A

called partial pressure (Px)

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10
Q

Diffusion rate of each gas is ______ ______ to its partial pressure gradient.

A

directly proportiona

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11
Q

Total gas pressure of a mixture of gases ( Ptot ) equals?

A

The sum of partial pressures of all gases

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12
Q

Ptot = r

A

PO2 + PN2 + PCO2 + Pother

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13
Q

Order the gasses in order of highest partial pressure to lowest. ( In the air)
PN2, PO2 , PCO2, Pother

A

PN2,
P02
PCO2
Pother

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14
Q

True or false. Gas dissolved in water and tissues exerts its own partial pressure on surface of membrane in opposite way as gas does in gas phase

A

False. Gas dissolved in water and tissues exerts its own partial pressure on surface of membrane in same way as gas does in gas phase

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15
Q

Partial pressure of a dissolved gas is determined by what two factors?

A

it’s concentration & solubility coefficient

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16
Q

Henry law states that?

A

Partial Pressure = Concentration of the dissolved gas/ Solubility Coeff.

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17
Q

The Measure of electro-chemical attraction that a dissolved gas has to water molecules is otherwise known as?

A

Solubility coefficient

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18
Q

If a gas is highly soluble, will more or less gas molecules be able to dissolve before the partial pressure of that gas within the solution increases?

A

MORE

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19
Q

True or false, CO2 is 24 times more soluble than O2 in fluid?

A

True

20
Q

With temperature being constant order these from most soluble to least?
CO2,N2, O2 CO, Helium

A

CO2
O2
CO
N2

Helium

21
Q

PO2 in gas phase in alveoli (PAO2) <> PO2 dissolved in blood (PaO2)

A

PA02&raquo_space;PaO2

22
Q

Net diffusion of O2 is from ____ to blood

A

Alveoli to pulmonary arterial ( Due to partial pressure gradient of O2)

23
Q

PCO2 in gas phase in alveoli (PACO2) &laquo_space;or&raquo_space;PCO2 dissolved blood (PaCO2)

A

PACO2 &laquo_space;PaCO2

24
Q

Direction of Net diffusion of CO2 ?

A

From pulmonary arterial blood to alveoli

25
Q

True or false?Water molecules, as other dissolved gas molecules, are continually escaping from water surface into gas phase

A

True.

26
Q

Partial pressure exerted by Which water molecules is called water vapor pressure (Ph2o)

A

Water molecules, as other dissolved gas molecules, are continually escaping from water surface into gas phase

27
Q

What is the purpose of water vapor in the air passageways?

A

Water vapor humidifies inspired air in passageways

28
Q

As Temp increases, kinetic activity of molecules and likelihood that will escape from water surface into gas phase increase or decreases?

A

Increase.

Thereby increasing their partial pressures/

29
Q

Net rate of diffusion in fluids is affected by pressure difference + several other factors? What are they?

A 
Solubility of gas in fluid
Cross-sectional area of fluid
Distance through which gas must diffuse
Molecular weight of gas
Temperature of fluid (in body, remains constant
30
Q

How do you calculate diffusion rate? ( EQN)

A

Diffusion rate ~ [(P1-P2 ) * Area * Solubility]/[Distance * sqrt(MW)]

31
Q

Main gases involved in respiration are highly soluble in _____? And Why (3). ( Hint: tissue diffusion)

A

Lipids.

  1. Cell membranes are phospholipid bilayers
  2. So diffusion through membrane is not an issue
  3. Diffusion of gases through tissues will therefore be almost = to diffusion through water
32
Q

True or false. Composition of alveolar air = atmospheric air

A

False.

Alveolar air is only partially replaced by atmospheric air with each breath

33
Q

What are the difference between alveolar air and atmospheric air, if any?

A

Alveolar air is only partially replaced by atmospheric air with each breath
ALV air = O2 is constantly being absorbed into pulmonary blood from alveolar air
CO2 is constantly diffusing from pulmonary blood to alveoli
Dry atmospheric air that enters airways is humidified before reaches alveoli

34
Q

____ Air Almost entirely composed of nitrogen and oxygen

A

Atmospheric air

35
Q

Atmospheric air has Almost no _______and little ____ vapor

A

carbon dioxide

water

36
Q

As soon as air enters airways, it is exposed to _______covering surfaces and gets _____?

A

fluids

humidified

37
Q

When atmospheric air enters the air ways and gets humidified, ________ will dilute other gases
(hint humidified)

A

Water vapor

38
Q

Rate of removal of excess gas from alveoli depends on?

A

rate of alveolar ventilation (VA)

39
Q

true or false. Quick replacement of alveolar air

is important in preventing sudden changes in gas concentrations in blood? Why is this important?

A

False. Slow replacement Is important for this because it stabilizes respiratory control mechanisms

40
Q

Average functional residual capacity (FRC) ~ 2300 ml. is all this brought into the alveoli?

A

No. ~350 ml of new air per normal resting breath is brought into alveoli. Due to slow removal rate –> important for preventing sudden changes in alveolar blood gas composition

41
Q

The CO2 concentration (CACO2) and PCO2 in alveoli (PACO2) depend on?

A
  1. Excretion rate of CO2 from pulmonary arterial blood into alveoli
  2. The rate of alveolar ventilation to expire CO2
42
Q

Increase of CO2 excretion rate ______ C(A)CO2 and alveolar P(A)CO2

A

increases

43
Q

Increase of ventilation rate _______the alveolar PACO2 and CO2 concentration (CACO2)

A

decreases

44
Q

A normal expired air is a mixture of_____ and _____air

A

alveolar air and dead space air

45
Q

True or false alveolar air is the last 1/3 of volume of expired air

A

True

EXCI 357 Pulmonary Physiology (7 decks)

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