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OLD "MBS 603" > Exam 3 -- Lecture 1 > Flashcards

Exam 3 -- Lecture 1 Flashcards

1
Q

What is compliance?

A

distensibility of the lung and chest wall

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2
Q

What does lung compliance depend on?

A

amount of elastic tissue

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3
Q

When you breath in, the thoracic cavity becomes larger and the pressure in the thorax pressure RISES/FALLS?

A

pressure falls; allowing lungs to expand and fill

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4
Q

When alveoli are filled to their limit, are they MORE/LESS compliant?

A

less compliant; stiffer

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5
Q

When you breath out, the thoracic cavity becomes smaller and the pressure in the thorax pressure RISES/FALLS?

A

pressure increases; forcing air out of lungs

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6
Q

What is the relationship of compliance with volume and pressure?

A

compliance is proportional to volume
compliance is inversely proportional to pressure

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7
Q

What is hysteresis?

A

pressure and volume are different for inspiration vs expiration

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8
Q

Why does the pressure volume curve look different for inspiration vs expiration?

A

different surface tensions at air-liquid interface of lungs
* air-liquid interface is special

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9
Q

Its difficult for alveoli to expand because there is a strong molecular force holding liquid in them together, what solves this problem?

A

surfactant

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10
Q

What cells make surfactant?

A

type II alveolar cells

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11
Q

What is surfactant made of ?

A

phospholipids

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12
Q

How does surfactant work?

A

breaks the surface tension allowing lungs to expand/inflate rapidly

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13
Q

Exhaling is a passive process so as you exhale lung surface area decreases faster than surfactant can be removed so the density of surfactant in epithelial fluid __________ and the curve is fairly flat. However as lung volume decreases, surfactant is removed and surface tension begins to ___________ again.

A

increases

increase

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14
Q

Why does the saline inflation of a lung has more compliance?

A

doesn’t have to get past air-fluid interface to break surface tension

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15
Q

What is the law of LaPlace?

A

attractive forces between molecules of liquid causes small alveoli to have very high surface tension that is hard to overcome

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16
Q

What is the relationship between pressure and radius?

A

inversely proportional
- larger radius alveoli = lower pressure (easier to keep open)

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17
Q

SMALL/LARGE alveoli make it harder to breathe

A

small

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18
Q

Smaller alveoli make it harder to breath but they are required for…

A

gas exchange (increased surface area)

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19
Q

The smaller the alveoli the LARGER/SMALLER the pressure

A

larger

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20
Q

_____ is the substance that keeps small alveoli open and available for gas exchange

A

surfactant

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21
Q

Without surfactant atelectasis would happen, what does that mean?

A

small alveoli would collapse

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22
Q

Does surfactant increase or decrease lung compliance?

A

increase (reduces work required)

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23
Q

What secretes surfactant lipids in type II alveolar cells?

A

lamellar bodies

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24
Q

If lungs were deficient in surfactant, would the opening pressure be higher or lower?

A

higher

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25
Q

If lungs were deficient in surfactant, would it be easier or harder to inflate?

A

harder

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26
Q

If lungs were deficient in surfactant, would the deflation stability be better or worse?

A

worse

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27
Q

If lungs were deficient in surfactant, would the lung volume increase or decrease?

A

decrease

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28
Q

If you have increased compliance, will the line on a pressure volume curve move left or right?

A

left
easily breathe in & harder to breathe out (increased volume with lower pressure)

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29
Q

If you have decreased compliance, will the line on a pressure volume curve move left or right?

A

right
harder to breathe in & easier to breathe out
(decreased volume with higher pressure)

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30
Q

What is a disorder that has increased compliance?

A

emphysema/COPD

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31
Q

What is a disorder that has decreased compliance?

A

fibrosis

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32
Q

In emphysema, is it harder to breath in or out?

A

harder to breathe out

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33
Q

In fibrosis is it easier to breath in or out?

A

harder to breathe in

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34
Q

Why is there an increase in compliance in emphysema/COPD?

A

loss of elastic fibers causes difficulty in contracting lungs to breathe out but they fill easily

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35
Q

Why is there an decrease in compliance in fibrosis?

A

build up of scar tissue causes difficulty pulling air in to expand lungs but they exhale easily

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36
Q

What is the condition NRDS?

A

lack of surfactant
common in premature babies

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37
Q

Is the pressure normally in the pleural space positive or negative and why?

A

negative
parietal pleura are attached to chest wall and are being pulled outwards
HELPS HOLD LUNGS OPEN

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38
Q

If there is a puncture in the pleura the lungs ________ and the chest wall ________

A

collapse
springs out

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39
Q

What are the 3 types of pneumothoraxes?

A

closed
open
tension

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40
Q

What is a closed pneumothorax?

A

damage to lungs causing air to leave lungs and into the pleural space

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41
Q

In a closed pneumothorax, the pleural space pressure is <, >, = atmospheric pressure?

A

pleural pressure < atm

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42
Q

What is an open pneumothorax?

A

damage to chest wall causing air to rush from outside into pleural space cavity

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43
Q

In an open pneumothorax, the pleural space pressure is <, >, = atmospheric pressure?

A

pleural pressure = atm

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44
Q

What is a tension pneumothorax?

A

damage to chest wall but flat covers hole resulting in air building up in pleura space because it cannot leave

air comes in pleural space but cannot come out

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45
Q

In a tension pneumothorax, the pleural space pressure is <, >, = atmospheric pressure?

A

pleural pressure > atm

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46
Q

What is so life threatening about a tension pneumothorax?

A

pressure of chest can push on heart lowering cardiac output and venous return resulting in shock

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47
Q

What is the normal value for PA O2?

A

(alveolar)
104 mmHg

48
Q

What is the normal value for Pa O2 in systemic arterial blood?

A

(arterial)
100 mmHg

49
Q

What is the normal value for PA CO2?

A

(alveolar)
40 mmHg

50
Q

What is the normal value for Pa CO2 in systemic arterial blood?

A

(arterial)
40 mmHg

51
Q

What is the normal value for Pa CO2 in mixed venous blood?

A

(arterial)
46 mmHg

52
Q

What is the normal value for Pa O2 in mixed venous blood?

A

(arterial)
40 mmHg

53
Q

What 3 reasons are the PA O2 is lower than atmospheric air?

A
  1. water vapor reduces amount of O2
  2. some old air left in alveolar
  3. Co2 being taken up into alveolar dilutes O2 levels
54
Q

Pulmonary circulation is the output of the _______ ventricle

A

right

55
Q

Is pulmonary circulation a high or low pressure system?

A

low pressure

56
Q

How is pulmonary flow regulated?

A

change in resistance in pulmonary arterioles

57
Q

What is the most important regulator of pulmonary flow?

A

PA O2 (alveolar pressure of O2)

58
Q

If PA O2 falls, resistance INCREASED/DECREASES and blood flow RISES/FALLS.

A

resistance increases
flow falls
* doesn’t seem right but its because blood flow diverts flow hypoxic alveolar to ones that work

59
Q

When PA O2 drops why does the resistance there increase and blood flow decreases?

A

want to divert blood away from hypoxic alveoli to ones that work

60
Q

Gas exchange relies on a __________

A

gradient

61
Q

Why is distribution of blood flow uneven in the lungs?

A

gravity

62
Q

Where is blood flow the lowest in the lungs?

A

zone 1 (apex)

63
Q

Where is blood flow the highest in the lungs?

A

zone 3

64
Q

In zone 1 of the lungs, PA ___ Pa ___Pv

A

PA > Pa > Pv

65
Q

In zone 2 of the lungs, Pa ___ PA ___Pv

A

Pa > PA > Pv

66
Q

In zone 3 of the lungs, Pa ___ Pv ___PA

A

Pa > Pv > PA

67
Q

Why is ventilation in zone 1 of lungs lowest?

A

alveoli get filled first so they are largest = less compliant = decreased blood flow (alveoli pushing on vessel)
* see slide 27

68
Q

Why is ventilation in zone 3 of lungs highest?

A

alveoli are filled last so they are small = more compliant = increased blood flow (alveoli aren’t pushing on vessel)
* see side 27

69
Q

Why is there a difference in the extent of ventilation in the lungs?

A

mixture of compliance, weight on lungs, and gravity

70
Q

What alveoli experience greater change in volume and are better ventilated?

A

zone 3

71
Q

What alveoli have more of a negative intrapleural pressure?

A

zone 1
expand the most

72
Q

What part of the lungs in the least compliant?

A

apex (zone 1)

73
Q

Blood flow and ventilation are the highest where in the lungs?

A

bottom

74
Q

V/Q (ventilation/perfusion) ratio is highest at the top or bottom of the lungs?

A

top

75
Q

Why is the V/Q ratio highest at the top of the lungs?

A

more ventilation but less perfusion at top

large V / small Q

76
Q

What is the normal V/Q ratio?

A

0.8

77
Q

What 4 components control breathing?

A
  1. brainstem
  2. chemoreceptors
  3. mechanoreceptors
  4. respiratory muscles
78
Q

What 2 structures in the brain stem control breathing?

A

medulla
Pons

79
Q

The dorsal side of medulla controls inspiration or expiration?

A

inspiration

80
Q

The ventral side of medulla controls inspiration or expiration?

A

expiration

81
Q

The dorsal respiratory group controls what?

A

rhythm of inspiration (send signals to diaphram to contract)

82
Q

The dorsal respiratory group receives input from what?

A

pre-Botzinger complex

83
Q

Where does the dorsal respiratory group send its message?

A

diaphragm (to increase contractions)

84
Q

The ____________ respiratory group is not very active during quiet breathing why?

A

ventral

expiration is a passive process

85
Q

When does the ventral respiratory system become active?

A

exercise

86
Q

The ventral respiratory system plays a role in the ______ reflex via the pre-Botzinger complex

A

sigh

87
Q

What are the 2 pontine (Pon) centers?

A

apneustic center
pneumotaxic center

88
Q

What is the apneustic center?

A

(1 of the pontine centers) “stimulatory” causes prolonged inspirations and short expirations

89
Q

What is the pneumotaxic center?

A

(1 of the pontine centers) “inhibitory” shuts off DRG thereby controlling volume of inspiration

90
Q

Do central chemoreceptors communicate with inspiration or expiration centers?

A

inspiration centers

91
Q

What gas primarily controls the medulla chemoreceptors?

A

CO2

92
Q

Central chemoreceptors are most sensitive to changes in _____

A

pH

93
Q

What enzyme catalyzes the reaction of CO2 + H2O —> H2CO3 —> H+ + HCO3-?

A

carbonic anhydrase

94
Q

What gas is permeable across the BBB and is important for central chemoreceptors?

A

CO2

95
Q

Can the CO2 + H2O —> H2CO3 —> H+ + HCO3- reaction occur in the CNS?

A

yes; this is how central chemo receptors sense changes in pH

96
Q

Peripheral chemoreceptors are most senstitive to decreases in arterial _______

A

Pa O2

97
Q

As blood CO2 increases, pH of CNS increases/decrease which is sensed by central chemoreceptors?

A

decreases

98
Q

When blood CO2 increases, pH of CNS decreases which is sensed by central chemoreceptors which sends a message to DRG to increase/decrease breathing.

A

increase breathing

99
Q

Where are peripheral chemoreceptors located?

A

carotid bodies and aortic arch

100
Q

What are peripheral chemoreceptors most sensitive to changes in?

A

O2

101
Q

Carotid body (peripheral chemo)receptors responds to Pa O2 < ______ mmHg

A

60

102
Q

What receptor receives more blood than any other organ?

A

peripheral chemoreceptors

103
Q

Activation of peripheral chemoreceptors increases/decreases the rate of breathing?

A

increases

104
Q

What activates peripheral chemoreceptors?

A

drop in O2

105
Q

Decreases in pH are mediated only by peripheral receptors in __________

A

carotid bodies

106
Q

Sensory information received at peripheral chemoreceptors is relayed to __________

A

DRG

107
Q

What are mechanoreceptors?

A

receptors that sense stretch in muscles (of lungs or limbs)

108
Q

What is the Herin-Breur reflex?

A

mechanoreceptors in lungs sense stretch and initiate creased breathing rate by increasing expiration

109
Q

Mechanoreceptors in limb muscles and joints sense movement and instruct __________ center to increase breathing rate

A

inspiratory center

110
Q

Mechanoreceptors in the limbs are part of the ___________ response to exercise (feed-forward)

A

anticipatory

111
Q

What do irritant receptors do?

A

in between epithelial cells in airways that cause constriction of bronchial muscles to increase breathing rate

112
Q

What do J receptors do?

A

in alveolar walls that sense growing of capillaries and will increase interstitial fluid volume = decreased breathing rate

113
Q

What zone is pressure highest in the lungs?

A

zone 1 (apex)

alveolar pressure is highest, and pulmonary blood flow is limited

114
Q

What central control center controls holding breath?

A

pneumotaxic

115
Q

Where are the central chemoreceptos located?

A

under medualla

116
Q

If you increase dead volume is it harder or easier to breath and why?

A

harder
increases resistance

117
Q

If an airway has a smaller radius, does the resistance increase or decrease?

A

increased resistance

OLD "MBS 603" (22 decks)

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