Session 2 - part II Flashcards Preview

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Flashcards in Session 2 - part II Deck (44)
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1
Q

What is the partial pressure of O2 in alveolar air?

A

13.3 KPa (Atmospheric is 21 KPa)

2
Q

What is the partial pressure of CO2 in alveolar air?

A

5.3 KPa (Atmospheric is tiny <1)

3
Q

What is the partial pressure of O2 and CO2 in venous blood?

A

6.0 KPa O2 & 6.5 KPa CO2 (at rest)

These values vary with different levels of metabolism

4
Q

What causes O2 to diffuse into the blood?

A

The partial pressure of O2 in the alveolar gas is greater than the partial pressure of O2 in the returning blood.

5
Q

What causes CO2 to diffuse into the alveoli?

A

The partial pressure of CO2 in the alveolar gas is lower than the partial pressure of CO2 in the returning blood.

6
Q

What does diffusion of gases depend on?

A

Area
Gradients
Dsitance

7
Q

What does resistance to diffusion depend on?

A

Nature of the barrier

Nature of the gas

8
Q

How does the barrier effect gas exchange in the alveoli?

A
The gas has to diffuse through other gases and the alveolar wall which has;
Simple squamous epithelium
Tissue fluid
Simple squamous of the vessel
Plasma
Membrane of the red blood cell
9
Q

Diffusion of gases through gases is inversely proportional to what?

A

Molecular weight

10
Q

Which molecule is heavier out of CO2 & O2?

A

CO2 is heavier

11
Q

Which molecule is more soluble out of CO2 & O2?

A

CO2

12
Q

What gas transports the fastest?

A

CO2 so exchange of O2 is always limiting

13
Q

How thick is the barrier for oxygen transport in the alveoli?

A

0.6 micro meters

14
Q

How can you determine the gas composition in the alveoli?

A

Take a sample from an artery in the wrist, the partial pressures will be the same here as in the alveoli

15
Q

Define ventilation

A

Expansion of the lungs which increases the volume of the respiratory bronchioles and alveolar ducts so air can flow down the airways to them.

16
Q

Which parts of the airways can/cannot expand?

A

Can - Respiratory bronchioles, alveolar ducts

Cannot - Rest of respiratory system

17
Q

How can you measure the ventilation?

A

A spirometer - Patient breathes from a closed chamber (Pressure held constant) over water whose volume changes with ventilation

18
Q

Define Tidal volume

A

Volume in and out of the same airways with each breath

19
Q

Define Inspiratory reserve volume

A

The extra volume that can be breathed in over the Tidal volume at rest

20
Q

Define Expiratory reserve volume

A

The extra volume that can be breathed out over the Tidal volume at rest

21
Q

Define Residual volume

A

The volume left in the lungs at maximum expiration.

22
Q

How do you measure Residual volume?

A

Using Helium dilution, not a spirometer

23
Q

Why do lung capacities not vary?

A

They’re measured from fixed points in the breathing cycle, so better clinically as they are always the same as always taken at the same point.

24
Q

Define Vital capacity

A

Maximum inpsiration to maximum expiration.
The biggest breath that can be taken and is often effected in disease
Usually 5L

25
Q

Define Inspiratory capacity

A

The biggest breath that can be taken from resting expiratory level
Usually 3L

26
Q

Define Functional residual capacity

A

Volume of air in the lungs at resting expiratory level.
Usually 2L
Expiratory reserve + Residual volume

27
Q

Define Ventilation rate

A

Amount of air moved in and out of a space per minute. It is the product of volume moved per breath and respiratory rate

28
Q

Define Pulmonary ventilation rate

A

Tidal volume x Respiratory rate

29
Q

What is Dead space?

A

Due to the air entering and leaving the system via the same airways, the last air stays in the airways and is the first air out. Therefore it never reaches the alveoli and is wasted.

30
Q

What is the alveolar ventilation rate?

A

The amount that reaches the alveoli

Dead space is taken into account

31
Q

Define Serial dead space

A

The volume of the airways
Measured using a nitrogen washout
Usually 0.15L

32
Q

Define Distributive dead space

A

Parts of the lung which are not airways, but don’t support gas exchange due to being dead, damaged or having poor perfusion.

33
Q

What is Physiological dead space?

A

Distributive dead space + Serial dead space

Usually 0.17L

34
Q

How do you calculate dead space ventilation rate?

A

Dead space volume x Respiratory rate (number of breaths per min)

35
Q

What type of breathing is most work, but gets most air to the alveoli?

A

Deep breathing

36
Q

What is the standard Tidal volume?

A

0.5L

37
Q

What is Pulmonary ventilation rate?

A

Tidal Volume x Respiratory Rate

38
Q

What is the standard Inspiratory volume?

A

2.5L

39
Q

What is the standard Residual volume?

A

0.8L

40
Q

What is the standard Expiratory volume?

A

1.5L

41
Q

What is the standard Functional residual capacity?

A

2.3L

42
Q

What is the standard Inspiratory capacity?

A

3.0L

43
Q

What is the standard Vital capacity?

A

5.0L

44
Q

What is the standard Lung capacity?

A

5.8L