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Flashcards in Ventilation Deck (63):
1

Charle's Law

Volume of a gas increases linearly with temperature

2

Boyle's Law

Pressure of a gas is inversely related to the volume of the container

3

Henry's Law

Gases diffuse from high to low pressure

4

Inspiration is primarily work of

Diaphragm

5

What does visible contraction of accessory muscles suggest

Respiratory issues, obstruction like asthma maybe

6

Expiration Muscles

Gravity!
passive foreceful - abdominal muscles

7

Diaphragm

Attached to lower ribs and sternum
Separates thoracic and abdominal cavities

8

What is diaphragm made of

Skeletal muscle - slow twitch with tons of mitochondria
Innervated by phrenic C3,4,5

9

Diaphragm accounts for ___ % of volume change with resting breathign

75%

10

With contraction the diaphragm...

Descends
Increase in lung volume
Inhale

11

At the end of expiration pressures are...

Equal, so no movement in or out of lungs

12

Inspiration begins with...

contraction of inspiratory muscles to inc alveolar volume and expand lungs

13

Increased alveolar volume causes...

decrease in alveolar pressure below barometric press. so air flows into the lungs

14

At the end of inspiration....

Thorax and alveoli stop expanding, airflow in causes alveolar pressure to be equal to the baro press and so not that it is equal no movement occurs

15

During expiration volume of thorax...

Decreases as the diagphragm relaxes, decrease in alveolar volume and increase in alveolar pressure

16

Tidal Volume

500mL

17

Vol. in Conducting Airway

150 mL

18

Is the air in conducting airway participating in gas exchange

NO - gas exchange occurs at alveoli

19

Anatomic Dead Space

NOT part of gas exchange

20

With each 500mL inspiration, only...

the initial 350mL of fresh air entering the nose get to the alveoli

21

With each 500mL expiration, only...

the final 350mL of air exiting the nose comes from alveoli

22

Minute Ventilation (VE)

Total air moved into and out of respiratory system each minute
Volume that you breathe in/out times the # of times you breathe

23

Alveolar Ventilation (VA)

Volume of air available for gas exchange/minute
Have to consider dead space (VD) = air that doesn't participate in gas exchange

24

Pleural membranes are essential for

Keeping the lung open

25

Pleural Cavity

Encapsulates the lung; formed by the pleural membranes

26

Visceral Pleura

Adherent to the lung

27

Parietal Pleura

Adherent to the chest wall

28

Pleural Fluid

8mL
Adheres to the two pleural membranes
Comes from intercostal arteries; drained by lymphatics

29

Pleural Effusion

Common with congestive heart failure
Due to increased pulmonary venous hydrostatic pressure

30

Pleural Pressure

Opposing elastic force acts on pleural membranes which creates a negative pressure

31

Negative Pleural Pressure is result of

outward recoil of the chest wall and inward recoil of the lungs
Chest wall = out and lungs = collapse in

32

Balance of the two forces

FRC is the equilibrium volume when the elastic recoil of the lung is balanced by normal tendency for chest wall to spring out

33

At FRC the recoils are

at equilibrium
Changes in lung or chest wall elastic properties will change the FRC

34

Chest Wall Recoil

If unopposed by lung recoil, would cause expansion to 70% of TLC
At TLC, chest wall has inward recoil
At RV chest wall has outward recoil

35

Lung Recoil

If unopposed (disconnected) from chest wall, lung would collapse

36

Airway Pressure (Paw)

Pressure inside the airway

37

Alveolar Pressure (PA)

Pressure inside alveoli

38

Pleural Pressure (Ppl)

Pressure inside pleural space (btw lung and chest wall)

39

Transmural Pressures

Pressure diff across a wall (inside-outside)

40

Types of Transmural Pressures

Transpulmonary
Transairway

41

Transpulmonary Pressure (PL)

Pressure diff across lung wall
PA - Ppl
Always positive
If 0 = lung collapse

42

PL is equal and opposite to...

the elastic recoil of lung

43

Transairway Pressure (Pta)

PRessure diff across airway
Paw - Ppl

44

Inspiratory muscles contract -->

1. Thoracic Cavity Expands
2. Pleural Press becomes more neg
3. Transpulmonary press inc
4. Lungs inflate
5. Alveolar press becomes subatmospheric
6. Air flows into lungs until alveolar press equals atm press (peak of inhalation)

45

Compliance

Distensibility
Ease with which lungs and thorax expand

46

The greater the compliance...

the easier for a change in pressure to cause expansion

47

Lower compliance means

lungs are working harder to expand

48

Elastance

The reciprocal of compliance
Tendency to return to original shape when deformed
Elastic recoil

49

Inc in lung compliance and volume

Inc in lung compliance for given pressure will get a greater change in volume

50

Dec in lung compliance and volume

Dec in lung compliance for given pressure will get you lower volume change

51

Decrease in compliance (disorders)

Resistive lung disorder
Pulmonary fibrosis
Easy in, hard out

52

Increase in compliance (disorders)

COPD, asthma, obstructive lung disorder

53

Pleural pressure uniformity

is NOT uniform

54

Pleural pressure is not uniform due to

1. Gravity
2. Mismatching of shapes of lungs and chest wall
3. Weight of lung

55

What is more constant throughout the lung

Alveolar pressure

56

Apex vs. base for pressure

Gravity is pulling more on membrane at apex, so there is lower pressure at apex relative to the base

57

Regional Compliance differences result in

Regional differences in ventilation

58

Compliance is ___ at apex

Less
Gravity pulls lungs down, dec in pleural press at apex, inc in transpulmonary pressure at apex, inc in alveolar expansion at apex, decrease in compliane

59

At FRC and above... The Paradox

Even though the base is poorly expanded, it is better ventilated
More volume will go to the more distensible base than to the stiffer apex

60

Below FRC...

It is reversed
As one approaches RV, pleural press at base exceeds airway press and the airways close at the base
Inspiration from RV ventilates alveoli at apex
Base is not ventilated until pleural press is less than atm press

61

Hysteresis

Volume lower when you inhale than when you exhale for a given pressure
Fighting surface tension

62

Alveoli at base are

smaller or weaker looking, but they are more distensible so the volume change is bigger at the base - more compliant

63

Lower Zone

Higher ventilation
So better to ventilate at base
Because compliance for given pressure is better