Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Respiratory System > Gas Exchange: Properties Of Gases And Diffusion > Flashcards

Gas Exchange: Properties Of Gases And Diffusion Flashcards

1
Q

What is Boyle’s law?

A

Pressure of a gas is inversely proportional to its volume

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

How do you calculate the partial pressure of a gas in moist air?
Use O2 as an example

A

pX = (atm - SVP) x X

Atmospheric pressure: 101kPa
Saturated vapour pressure: 6.28kPa
O2 makes up 20.9% of air

pO2 = (101 - 6.28) x 0.209 = 19.8kPa

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

How do you calculate the amount of a dissolved gas?

A

partial pressure x solubility coefficient of gas

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What is the total pressure of a mixture of gases?

A

The sum of the partial pressure of all the gases

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Gases dissolve + diffuse according to their…

A

Partial pressures

From area of high partial pressure to lower partial pressure

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

The amount of dissolved gas in a liquid is proportional to its ** above the liquid and to the ** in that liquid

A

The amount of dissolved gas in a liquid is proportional to its partial pressure above the liquid and to the gas’ solubility in that liquid

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What is the amount of dissolved gas in a liquid proportional to?

A
  • it’s partial pressure above the liquid
  • the gas’ solubility in the liquid
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What layers do gas have to diffuse through from alveolar air to RBC?

A
  • fluid film lining alveolus
  • epithelial cell of alveolus
  • interstitial space
  • endothelial cell of capillary
  • plasma
  • red cell membrane
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Compare CO2 and O2 in terms of their:
- solubility
- molecular weight

A
  • CO2 is more soluble than O2
  • CO2 greater molecular weight

Effect of solubility is greater than MW

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

How is diffusion impaired in fibrotic lung disease?

A

Thickened alveolar membrane > larger diffusion distance

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

How is diffusion impaired in pulmonary oedema?

A

Fluid in interstitial space > increases diffusion distance

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

How is diffusion impaired in emphysema?

A

Destruction of alveoli > reduces SA for gas exchange

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What factors affect the rate of diffusion?

A
  • partial pressure difference/gradient
  • surface area available for diffusion
  • diffusion distance
  • diffusion coefficient of the gas
  • solubility of the gas in liquid
  • molecular weight of gas
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

How does the solubility of the gas affect diffusion?

A

Greater the solubility
Faster the rate of diffusion

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

How does the molecular weight of a gas affect diffusion?

A

Higher molecular weight
Slower rate of diffusion

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Normal ventilation perfusion ratio

A

0.8

17
Q

What does V + Q stand for in V/Q ratio?

A

V - alveolar ventilation
Q - perfusion (pulmonary blood flow)

18
Q

What does normal V/Q depend on?

A

Normal resp rate
Tidal volume
Cardiac output

19
Q

What is the ideal V/Q?

A

1
Ventilation = perfusion

20
Q

Typical V/Q ratio across the lungs

A
  • alevoli at apex: under-perfused + over-ventilated > high V/Q ratio
  • alveoli at base: over-perfused + under-ventilated > low V/Q ratio
21
Q

Examples of conditions where there’s a V/Q mismatch of <1

A

Conditions where there is poor ventilation to the alevoli
pneumonia, moderate asthma, COPD

22
Q

Examples of conditions where there’s a V/Q mismatch of >1

A

Conditions where there is poor perfusion to the alevoli
pulmonary embolism

23
Q

What is the V/Q ratio if there is inadequate ventilation?

A

V/Q < 1

24
Q

What is the V/Q ratio if there is inadequate perfusion?

A

V/Q > 1

25
Q

What happens in V/Q mismatch if there is inadequate ventilation?

A
  • imparied gas exchange in affected alevoli
  • pO2 falls
  • pCO2 rises
  • lung hypoxic vasoconstriction occurs
  • causes diversion of blood to better ventilated parts
  • Hb in well ventilated alveolar capillaries are saturated already
  • no more O2 can bind
  • pO2 remains low
  • hyperventilation occurs > normal/low pCO2
26
Q

What is a respiratory shunt?

A

When you perfuse an unventilated alveolus, that bit of blood is wasted as no gas exchange occurs

27
Q

What is the compensatory mechanism in VQ mismatch?

A

Lung hypoxic vasoconstriction
Causes diversion of blood

28
Q

What is the value of saturated vapour pressure at body temp?

A

6.28kPa

Respiratory System (20 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions