Section 5 Lecture 4 Flashcards Preview

Physiology > Section 5 Lecture 4 > Flashcards

Flashcards in Section 5 Lecture 4 Deck (124):
1

alveolar pressure increases between ___ and decreases between ____:

middle of inspiration to middle of expiration, middle of expiration to middle of inspiration

2

When is alveolar pressure negative?

inspiration

3

When is intracellular pressure increasing?

expiration

4

Range of intracellular pressure:

-6 to -3 mm Hg

5

When is intrapleural pressure decreasing?

inspiration

6

How to measure pleural pressure:

esophageal balloon

7

Average volume of air exchanged in and out of lungs per breath:

500 mL

8

What is the flow limitation in inspiration?

None

9

distending pressure =

arterial pressure - pleural pressure

10

Arterial pressure =

pressure tending to collapse lung + pleural pressure

11

distending pressure =

pressure tending to collapse lung

12

These are equal at FRC:

Barometric and atmospheric pressures

13

Average pleural pressure:

-3 cm H2O

14

P(el) is equals and opposite to:

P(cw) P(el) = pressure tending to collapse lung, P(cw) = chest wall pressure

15

Sequence of events leading to inspiration:

inspiratory muscles contraction, chest wall expansion, P(pl) becomes more subatmospheric, lung expands, P(A) becomes sub-atmospheric, air flows into alveoli

16

No pull on lung to expand, lung collapses:

peumothorax

17

When can a pneumothorax occur from the inside?

if the P(pleural) is very positive, tumor, infection, or over expansion

18

True or False? Increasing surface tension makes it easier to reinstall a collapsed lung.

F. decreasing surface tension

19

True or False? Intracellular pressure matches atmospheric when the normal lung is at rest.

F. sub-atmospheric

20

How is the rib cage affected if there is a pneumothorax?

rib cage expands slightly (air flows in and lung collapses)

21

When does the lung volume plateau?

maximum vital capacity

22

True or False? The lung is always trying to collapse so it always has a positive pressure.

T.

23

What is positive pressure generated by?

recoil of lungs

24

True or False? Both chest wall and chest wall and lung (respiratory system) pressures can be both negative and positive.

T

25

% vital capacity at neutral point:

60%

26

% TLC at FRC:

40%

27

Which is more positive at FRC, chest wall pressure or respiratory system pressure?

respiratory system pressure

28

The slope of the lung pressure vs % vital capacity graph is linear until what % vital capacity?

75%

29

At what % vital capacity are lung pressure and respiratory system pressure equal?

about 55%

30

% TLC at RV:

25%

31

How is surface tension offset?

surfactant

32

Compliance dec w these 2 diseases:

Resp Distress Syndrome, Firbrosis

33

Low compliance require (larger/ smaller) translung pressure

larger

34

Emphysema destroys:

elastic recoil of lung, inc compliance

35

Translung P:

diff bw pleural and atmospheric

36

Compliance =

delta V/ delta P

37

Lungs compliance =

delta V/ delta P(pleural)

38

Average compliance:

0.2L / cm H2O

39

Is the lungs more or less distensible at high volumes?

less

40

What does compliance affect?

work of breathing

41

This disease results in inelastic scar-tissue:

Fibrotic Lung disease

42

This diseases results from a lack of surfactant in the lungs:

RDS

43

Compliance increases with this disease:

emphysema

44

If compliance is increased, will the translung pressure vs vital capacity graph shift up or down?

up

45

What corrects for the decreased compliance at higher volumes?

specific compliance

46

Types of phospholipids in surfactant:

DPPC, PG

47

Functions of proteins in surfactant:

regulate surfactant turnover, immune regulation, formation of tubular myelin

48

What causes the release of surfactant?

Beta adreneric agonist, activators of PKC, leukotrienes, purinergic agonist

49

How is surfactant cleared?

repute, lymphatics, macrophages

50

Which has higher pressure, small or large bubble if they have the same surface tension?

small bubble (P = 2T/r)

51

Law of LaPlace:

P = 2T/r

52

Without surfactant would the lower lung volumes require greater or less transmural pressure to keep the lungs expanded?

greater

53

What, besides surfactant, prevents alveoli from collapsing/

interdependence, channels that equalize pressure

54

Does compliance increase or decrease with increase in volume?

decrease

55

What does the slope of the P-V curve represent?

compliance

56

Does the slope (compliance) increase or decrease as delta p increases.

decreases

57

normal compliance value:

0.2 L/cm H2O (200 mL of air per 1cm H2O = 200mL/cm H2O

58

Which is on the x-axis in the P-V curve?

Pressure

59

Is the slope of the graph for a patient with emphysema greater or less than the normal curve?

greater. Remember: steeper curve (delta v/ delta P) = increases compliance. emphysema = high compliance (about 400 mL/cm H2O)

60

Is the slope of the graph for a patient with fibrosis greater or less than the normal curve?

less (Remember: steeper curve (delta v/ delta P) = increases compliance). fibrosis = low compliance (about 100 mL/cm H2O)

61

The work of breathing can be determined by the area under the curve of which graph?

Flow - Volume Loop

62

How would filling the lungs with fluid affected surface tension?

no surface tension

63

Is more or less pressure required to increase volume of lungs when filled with air vs. water

more

64

Does the compliance of the lungs increase or decrease when inflated with water?

increases

65

Is water inflation or air inflation non-compressible?

water inflation

66

Factors affecting lungs recoil;

elastic fibers (1/3) and surface tension (2/3)

67

How are compliance and recoil changed with fibrosis?

recoil increases. compliance decreases

68

How are compliance and recoil changed with emphysema?

recoil decreases, compliance increases

69

Diseases that cause changes in airway resistance:

asthma and emphysema

70

Shorthand calculation for airflow resistance:

1/r^4

71

What % of the total oxygen consumption and total cardiac output is used for moderate exercise?

1-3%

72

What % of the oxygen consumption is used in patients with pulmonary disease?

20-30% or more

73

What does lung recoil primarily influence?

tidal volume (V(T))

74

How is the tidal volume affected with an increase in compliance?

increases tidal volume

75

The lungs and chest walls can get up to what % of cardiac output?

20%

76

Expiratory flow rate (Vdot (E)) =

V(T) X frequency

77

What does airflow resistance primarily influence?

frequency

78

What factors can alter the viscosity of the air?

humidity and altitude

79

What can h=physically obstruct the upper airways?

mucus and other factors

80

These cause bronchoconstriction:

parasympathetic neurons (muscarinic receptors), histamine, leukotrienes

81

Factors affecting airway resistance:

length, viscosity, radius, mucus, edema, contraction of bronchial smooth muscle, increase air density (scuba diving)

82

What causes bronochodilation?

CO2, epinephrine (Beta 2- receptors)

83

How to calculate the total resistance for a system in series:

R1 + R2 + ...

84

How to calculate the total resistance for a systems in parallel:

1/R1 + 1/R2 +...

85

Does resistance to airflow increase or decrease as lung volume increase?

decreases

86

What pulls open the airways?

negative pleural pressure of inhalation

87

What causes the flow to be turbulent in the larger airways?

higher resistance and in series (and parallel)

88

True or False? Resistance in the large airways in only in series.

F. both series and parallel

89

Reynold's Number =

(2r (airwaY) v (airflow) d (of air))/ viscosity (of air)

90

Laminar flow will predominate when Reynold's number is

less than 2000

91

How will airflow be affected if the Reynold's number is less than 2000?

airflow for a given pressure will increase

92

If Reynold's number is greater than ____ turbulent flow will predominate.

2000

93

What 2 factors can increase turbulent flow?

increase in airflow velocity or increase in airway radius

94

Expirated ventilation is aka:

minute ventilation

95

Expired ventilation =

tidal volume X frequency (breathes per minute)

96

The optimum level of work is at how many breathes per minute?

15

97

How many mL is our expired ventilation (minute ventilation)?

6000 ml/min

98

Tidal volume for emphysema and pulmonary fibrosis relative to normal:

doubles to 1000ml for emphysema and about half to 200 for pulmonary fibrosis (breaths per minutes follow the same pattern)

99

Factors affected the rate of airflow through the airways:

Laminar vs. turbulent flow, airflow resistance in series and parallel, "flow limitation" (during expiration) and the "equals pressure point"

100

Factors that increase airway resistance:

mucus, edema, contraction of smooth muscle, inspired gas density and viscosity

101

How is inspiratory muscle effort affected with volume increases?

it increases

102

How is recoil of lung affected with volume increases?

it increases

103

How is airway resistance affected with volume increases?

it decreases

104

What does RV stand for?

Residual Volume

105

What fraction of tidal volume is expired during FEV(1)?

2/3

106

Peak flow rate in L/sec for both inspiration and expiration:

about 10 L/sec (at 25% of volume expired)

107

PEFR =

Maximal effort

108

What region represents the flow limitation?

effort-independent region

109

How does the maximum effort curve for a patient with asthma or emphysema compare to the normal curve?

lower than, generate less pressure

110

Is the expiratory flow or volume greater or less in a patient with emphysema or asthma?

less

111

True or False? The reserve volume for patients with emphysema or asthma is larger than normal.

F. smaller

112

average transpulmonary pressure:

30 cm H2O

113

Average transairway pressure:

30 cm H2O

114

Average pleural pressure:

-30 cm H2O

115

How will the pressure be affected if the gas velocity is increased?

pressure decreases

116

What is transairway pressure?

pressure difference between the airway opening and the alveolus.

117

What is transpulmonary pressure?

difference between the alveolar pressure and the intrapleural pressure in the lungs

118

Both transpulmonary and transairway pressures are calculated by subtracting this from a value:

pleural pressure

119

What becomes negative, transpulmonary or transairway pressure?

transairway

120

How is the resistive drop altered in a diseased state?

greater resistive drop

121

How is the equals pressure point affected in the diseased state?

it is close to alveoli in non-cartilage airways

122

How does the body try and offset the airway resistance in diseased state?

increase lungs volume

123

What will happen as airway resistance continues to increase?

crackles and rales on inspiration

124

When is airway compression required?

beyond the equal pressure point in expiration (negative transairway pressure)