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Respiratory system > Principles of gas exchange > Flashcards

Principles of gas exchange Flashcards

1
Q

What is a gas?

A

Collection of simple molecules moving randomly in a space

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2
Q

How do gas molecules move?

A

Move rapidly in straight lines
until they collide with other molecules
then they bounce away in a new direction

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3
Q

What is the pressure of a gas?

A

Force created by gas molecules colliding with a surface

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4
Q

What are the factors affecting pressure of a gas?

A

Volume

Number of gas molecules

Temperature

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5
Q

What is the volume of a gas?

A

The amount of space that the gas molecules occupy

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6
Q

How does increased volume of a gas affect its pressure?

A

Gas molecules have more space to move around in
fewer collisions with surface
decreases pressure

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7
Q

How does decreased volume of a gas affect its pressure?

A

Gas molecules have less space to move around in
more collisions with surface
increases pressure

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8
Q

What is the overall relationship between volume of a gas and its pressure?

A

Inversely proportional

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9
Q

How does an increased number of gas molecules affect its pressure?

A

More gas molecules moving around in the same amount of space
more collisions with surface
increases pressure

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10
Q

How does a decreased number of gas molecules affect its pressure?

A

Fewer gas molecules moving around in the same amount of space
fewer collisions with surface
decreases pressure

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11
Q

What is the overall relationship between number of gas molecules and its pressure?

A

Proportional

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12
Q

How does increased temperature of a gas affect its pressure?

A

Gas molecules have more energy
move around faster
more and harder collisions with surface
increases pressure

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13
Q

How does decreased temperature of a gas affect its pressure?

A

Gas molecules have less energy
move around slower
fewer and weaker collisions with surface
decreases pressure

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14
Q

What is the overall relationship between temperature of a gas and its pressure?

A

Proportional

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15
Q

What is the equation for the pressure of a gas?

A

Pressure = (n x T x R) / V

n = number of gas molecule
T = temperature
R = constant
V = volume of gas
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16
Q

What is the partial pressure of a gas?

A

In a mixture of gases

the pressure that each gas exerts is its partial pressure

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17
Q

What is the total pressure of a gas mixture?

A

In a gas mixture

the total pressure is the sum of all the partial pressures of the different gases in the mixture

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18
Q

What is meant by atmospheric pressure?

A

Pressure exerted by the weight of the air

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19
Q

How does atmospheric pressure change from higher altitudes to lower altitudes? Why?

A

It increases
because force of gravity increases
so the weight of air increases
more molecules in same volume

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20
Q

What is the actual atmospheric pressure at sea level?

A

101kPa = 760mmHg = 1atm

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21
Q

What gases make up atmospheric air? What are there relative proportions?

A

Nitrogen - 79%

Oxygen - 21%

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22
Q

How are the partial pressures of gases in atmospheric air calculated?

A

Nitrogen = 79% x 101kPa

Oxygen = 21% x 101kPa

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23
Q

What is the symbol for partial pressure?

A

p

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24
Q

What do gas molecules do they come into contact with fluid?

A

Some gas molecules dissolve in the fluid

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25
Q

What affects the partial pressure of a gas dissolved in a fluid?

A

The concentration of gas molecules dissolved in the fluid

The solubility coefficient of the gas

26
Q

How does an increased concentration of gas molecules dissolved in a fluid affect the partial pressure of the gas in the fluid?

A

More gas molecules in same volume
more collisions with surface
higher partial pressure

27
Q

How does a decreased concentration of gas molecules dissolved in a fluid affect the partial ressure of the gas in the fluid?

A

Fewer gas molecules in same volume
fewer collisions with surface
lower partial pressure

28
Q

What is the overall relationship between concentration of gas molecules dissolved in a fluid and the partial pressure of the gas in the fluid?

A

Proportional

29
Q

What is meant by the solubility coefficient of a gas?

A

How well the gas dissolves in water

30
Q

How does a lower solubility coefficient of a gas affect the partial pressure of the gas dissolved in a fluid?

A

Gas doesn’t dissolve as well in water, less surrounded by water molecules
makes more collisions with surface
increased partial pressure

31
Q

How does a higher solubility coefficient of a gas affect the partial pressure of the gas dissolved in a fluid?

A

Gas dissolves better in water, more surrounded by water molecules
makes fewer collisions with surface
decreased partial pressure

32
Q

What is the overall relationship between the solubility coefficient of a gas and the partial pressure of the gas dissolved in a fluid?

A

Inversely proportional

33
Q

What do water molecules do when they come into contact with air?

A

Water molecules evaporate from the fluid into the air as water vapour

34
Q

What is meant by vapour pressure of water?

A

Partial pressure of water vapour in air

35
Q

What are the factors of vapour pressure of water?

A

Temperature

36
Q

How does increased temperature affect vapour pressure of water?

A

Water molecules have more energy
more of them evaporate from fluid into air as water vapour
more water vapour in air
higher vapour pressure

37
Q

How does decreased temperature affect vapour pressure of water?

A

Water molecules have less energy
fewer evaporate from fluid into air as water vapur
less water vapour in air
lower vapour pressure

38
Q

What is the overall relationship between temperature and vapour pressure?

A

Proportional

39
Q

What direction do gases diffuse in?

A

From higher partial pressure to lower partial pressure

down their partial pressure gradient

40
Q

What are the factors affecting the rate of diffusion of a gas in a fluid?

A

Pressure difference

Solubility of gas in fluid

Cross-sectional area of fluid

Diffusion distance

Molecular weight of gas

Temperature of fluid

41
Q

How does the pressure difference affect the rate of diffusion of a gas in a fluid?

A

Bigger partial pressure difference between the two areas

the faster the rate of diffusion

42
Q

What is the overall relationship between the pressure difference and the rate of diffusion of a gas in a fluid?

A

Proportional

43
Q

How does an increased cross-sectional area of fluid affect the rate of diffusion of a gas in a fluid?

A

More space for gas molecules to diffuse through
more gas molecules diffuse across
faster rate of diffusion

44
Q

How does a decreased cross-sectional area affect the rate of diffusion of a gas in a fluid?

A

Less space for gas molecules to diffuse through
fewer gas molecules diffuse across
reduced rate of diffusion

45
Q

What is the overall relationship between the cross-sectional area of the fluid and the rate of diffusion of a gas in a fluid?

A

Proportional

46
Q

How does increased diffusion distance affect the rate of diffusion of a gas in a fluid?

A

Takes longer for gas molecules to diffuse across that distance
reduced rate of diffusion

47
Q

How does decreased diffusion distance affect the rate of diffusion of a gas in a fluid?

A

Doesn’t take as much time for gas molecules to diffuse across
faster rate of diffusion

48
Q

What is the overall relationship between the diffusion distance and the rate of diffusion of a gas in a fluid?

A

Inversely proportional

49
Q

How does increased solubility of a gas affect the rate of diffusion of a gas in a fluid?

A

More gas molecules dissolve into fluid
more of them diffuse across
increased rate of diffusion

50
Q

How does decreased solubility of a gas affect the rate of diffusion of a gas in a fluid?

A

Fewer gas molecules dissolve in fluid
fewer of them diffuse across
decreased rate of diffusion

51
Q

What is the overall relationship between the solubility of a gas and the rate of diffusion of a gas in a fluid?

A

Proportional

52
Q

How does increased molecular weight of a gas affect the rate of diffusion of a gas in a fluid?

A

Heavier gas molecules have less kinetic energy
move slower
reduced rate of diffusion

53
Q

How does decreased molecular weight of a gas affect the rate of diffusion of a gas in a fluid?

A

Lighter gas molecules have more kinetic energy
move faster
faster rate of diffusion

54
Q

What is the overall relationship between the molecular weight of a gas and the rate of diffusion of a gas in a fluid?

A

Inversely proportional

55
Q

Which of the factors of the rate of diffusion of a gas in a fluid are properties of the gas itself?

A

Solubility of gas

Molecular weight of gas

56
Q

What are the factors of a diffusion coefficient of a gas?

A

Solubility of gas

Molecular weight

57
Q

What is the diffusion coefficient of a gas?

A

Tells us the diffusion rate of a gas in a fluid at a certain partial pressure difference

58
Q

Does oxygen or carbon dioxide have a higher solubility coefficient?

A

Carbon dioxide

59
Q

Does oxygen or carbon dioxide have a larger molecular weight?

A

Carbon dioxide

60
Q

Does oxygen or carbon dioxide have a higher diffusion coefficient?

A

Carbon dioxide

Respiratory system (32 decks)

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