Respiratory physiology Flashcards

1
Q

ideal gas law

A

(Pb - Ph2o) x V = M x R x T

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2
Q

lung volumes

A
  1. residual volume - 1.5L
  2. expiratory reserve volume - 1.5L
  3. tidal volume - 0.5L
  4. inspiratory reserve volume - 2.5L
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3
Q

transmural pressure

A

Ptm = Pi - Po

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4
Q

lung capacities

A
  1. functional residual capacity (FRC)
  2. inspiratory capacity
  3. vital capacity
  4. total lung capacity
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5
Q

limiting ability of lung and chest wall

A

lung - limit expansion (inspiration)

chest wall - limit constriction (expiration)

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6
Q

sum of compliance

A

1/C(RS) = 1/C(L) + 1/C(CW)

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7
Q

pleural pressure

A

-6 cm H2O

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8
Q

effect of emphysema and fibrosis on lung compliance

A

emphysema increase lung compliance

fibrosis decrease lung compliance

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9
Q

interdependence of alveoli

A

one alveolus reduce volume, surr. alveoli expand

recoil force

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10
Q

surface tension

A

water molecule on surface - unequal pulling force - tension

keep air-fluid surface as small as possible

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11
Q

laplace law

A
P = 2(ST/r)
ST = surface tension
r = radius
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12
Q

surfactant

A

hydrophobic tail pulled toward air side of the air-fluid border - equalized force - reduce surface tension
90% lipid
10% protein
protein - albumin, IgA, SP-A, B, C, D

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13
Q

SP-A

A

important in exerting feedback control that limit the surfactant secretion

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14
Q

alveolar radius and surfactant

A
  • alveolar radius increase - surfactant thinner - surface tension increase
  • alveolar radius decrease, surfactant thicker - surface tension decrease
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15
Q

surfactant deficiency

A
  • glucocorticoids - stimulate surfactant production

- Infant Respiratory Distress Syndrome - IRDS - artificial surfactant given

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16
Q

surfactant production

A

alveolar type II

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17
Q

surfactant clearance

A

alveolar macrophage degrade surfactant

type II cell recycle or destroy the rest

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18
Q

hagen-poiseuille law

A

Q = (delta)P / R

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19
Q

silent lung disease

A

airway resistance of lower airway very low compared to the upper airway, obstructive disease in the lower air way do not display obstructive airway symptoms

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20
Q

factors affecting airway resistance

A
  1. density and viscosity of the inspired gas
  2. reduction in Pco2
  3. sympathetic and parasympathetic innervation and transmitters
  4. agents : histamine, acetylcholine, thromboxane A2, prostaglandin F2, and leukotrienes LTB4, C4 and D4
  5. lung volume
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21
Q

effect of reduction in PCO2

A

bronchoconstriction

- local hyperventilation -> reduction in PCO2 -> R(aw) increase -> divert the ventilation

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22
Q

bronchocontricting agent

A

histamine
thromboxane A2
prostaglandin F2

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23
Q

effect on lung volume on airway resistance

A

increase in lung volume -> decrease in airway resistance 6

FRC - R(aw) = 1.3cm H2O x I^-1 x s

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24
Q

beta2-adrenergic agonist

A

airway resistance reduced

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25
Q

forced expiration (4 compo)

A
  1. forced expiratory volumin in 1 sec (FEV1)
  2. forced vital capacity (FVC)
  3. Ratio (FEV1/FVC) - normal 80%
  4. peak expiratory flow rate (PEFR)
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26
Q

normal, obstructive, restrictive FEV1/FVC ratio

A

normal - 80%
obstructive - 42%
restrictive 90%

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27
Q

high volume of lung - high alveolar pressure

This is due to

A

increased recoil force of alveoli

better alignment of resp muscle

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28
Q

effort dependant region

A

bfore FEF 50%

graph change upon the patient’s effort

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29
Q

effort independant region

A

after FEF 50%

graph does not change upon patient’s effort

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30
Q

obstructive diesase

A

Residual volume increase
TLC increase
high resistance

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31
Q

restrictive disease

A

Residual volume and TLC both decrease proportionally

decreased lung volume

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32
Q

flow/volume curve - plateau

A

obstruction in extrathoracic airway

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33
Q

flow/volume curve - sharp drop

A

obstruction in intrathoracic airway

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34
Q

obstructive pulmonary disease

A

chronic bronchitis, emphysema, asthma

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35
Q

restrictive pulmonary disease

A

pulmonary fibrosis

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36
Q

compliance

A

change in volume / transmural pressure
transpural pressure for
lung = alveolar pressure - pleural pressure
chest wall = pleural pressure - outside pressure

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37
Q

alveolar membrane repair is done by…

A

type II alveolar cell

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38
Q

total ventilation, dead space ventilation, alveolar ventilation

A

toal vent = dead space vent + alveolar vent

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39
Q

normal total ventilation

A

8L/min

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40
Q

fraction of O2 in fresh air

A

21%

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41
Q

fraction of O2 in the used air

A

14%

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42
Q

calculation of dead space using Bohr equation

A

V(T) x F(E) = (V(T) - V(D)) x F(A) + V(D) x F(I)

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43
Q

basal metabolic rate - nomal range

A
VO2
250mL/min at 37C (98.6F)
275mL/min at 28C (100.6F)
225mL/min at 36C (96.6F)
chnage 11% per 1C change 
BMR - not eveyday regular, but the minimum required (early morning, lying on the bed)
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44
Q

normal adult oxygen comsuption

A

280mL/min

can be 10X higher at VO2 max

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45
Q

normal adult CO2 production

A

250mL/min

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46
Q

respiratory exchange ratio

A

R = CO2/O2
Glucose R = 1
Fat R = 0.7
protein R = 0.8

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47
Q

RQ (tissue) and R (lung) relationship

A

RQ = R in steady state - pulmonary gas exchage match the needs of metabolism in the peirpheral tissue
deviate during exercies, crying, breath holding, hyperventilation, hypoventilation

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48
Q

Dalton’s law

A

P(total) = P1 + P2 + P3

sum of partial pressures = total pressure

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49
Q

partial pressure of a gas X

A

Px = Fx x (P(B) - P(H2O))

Px x V = Mx x R x T
P(B) - P(H2O)) x V = M x R x T (sum of dry gases

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50
Q

inspired PO2 calculation

A

P(IO2) = F(IO2) x (P(B) - P(H2O))

IO2 = inspired O2
P(B) = 747 for sea level (usually 760), 347 for 20,000 feet, 247 for 29,035 feet (Mt. Everest)
P(H2O) = 47mmHg - constant through different altitudes 
F(IO2) = .21 - can change by breathing supplmental O2
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51
Q

alveolar PO2 (P(A)O2) calculation

A

P(A)O2 = P(I)O2 - (P(A)CO2 / R)

P(A)CO2 = usually 40mmHg

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52
Q

alveolar PCO2 (P(A)CO2) calculation

A

P(A)CO2 = 863 x (VCO2 / V(A))

VCO2 = produced in tissue - normal value = CO2 output = 250mL/min
V(A) = alveolar ventilation = normal value = 5400mL/min
53
Q

alveolar ventilation equation

A

V(A) = VCO2 / P(A)CO2 x 863

54
Q

alveolar PCO2 and arterial PCO2

A

they are equal

55
Q

increase in alveolar ventilation

A

decrease in PaCO2

increase in P(A)O2

56
Q

regular PIO2

A

147mmHg

57
Q

three types of alveolar ventilation

A

normoventilation
hyperventilation
hypoventilation

58
Q

hyperpnea

A

increased ventilation without change in PCO2 as in exercise

59
Q

tachypnea

A

breathing with an increased respiratory frequency

60
Q

alveolar-arterial PO2 difference

A

healthy person - 3-10 mmHg

normal anatomical shunts

61
Q

air bllod barrier (7 parts)

A
  1. alveolar epithelium
  2. tissue interstitium
  3. capillary endothelium
  4. plasma layer
  5. red cell membrane
  6. red cell cytoplasm
  7. gas binding to hemoglobin
62
Q

diffusion law

A
Vgas = D(L) x (P1 - P2)
D(L) = d x alpha x A/T
D(L) - diffusion capacity
d - diffusion coefficient
alpha - solubility
P1 - P2 = driving force 
P1 - away from
P2 - into 
D(L)CO2 = 20 x D(L)O2
63
Q

diffusion capacity measuring using CO

A
D(L)CO = VCO / (P(A)CO - PcCO)
PcCO = 0 
D(L)CO = VCO / P(A)CO
64
Q

factors influencing difusing capacity

A
  1. exercise
  2. body position
  3. body size
65
Q

pathological factor that reduce diffusing capacity

A

increase thickness
decrease surface area of alveolar-capillary membrane
decrease capillary volueme
edema - increase thickness
emphysema - decrease surface area
COPD, fibrosis, pulmonary edema, pneumonia

66
Q

mixed venous PO2

A

40 mmHg

67
Q

diffusion limitation

A

end capi PO2 and alveolar PO2 not matching (3-10mmHg is normal)
CO2 has no diffusion limitation

68
Q

exercise can unmask…

A

mild diffusion limitation

69
Q

causes of Low D(L)

A
  • decreased surface area
  • increased thickness
  • lung damage or disease
70
Q

normal alveolar PO2

A

100mmHg

71
Q

low alvelar PO2 (hypoxia)

A

deep hypoxia in combi with exercise can cause deffusion limitation in normal lung.

72
Q

alveolar-end capillary PO2 different

(A - C’)PO2

A

inequality between alveolar PO2 and end capillary PO2

73
Q

perfusion limitation

A

only way to increase tranfer of O2 is to add more blood. (increasing transit time does not increase the O2 transfer)

74
Q

what type of limitation does Nitrous oxide have?

A

perfusion limitation

(P1 - P2) quickly become zero

75
Q

what type of limitation does CO have?

A

diffusion limitation

  • CO to instantly bound to hemoglobin, so PCO is low, and that causes the diffusion limitation
  • P2 = O and P1 = constant
76
Q

what type of limitation dose O2 have?

A

usually perfusion limitation

77
Q

Fick’s law components (3 variables)

A

surface area - directly propor
partial pressure difference - directly propor
thickness - inversely propor

78
Q

diffusion capacity of lung is measure by…

A

CO

because PCO in the capillary is zero due to high affinity of hemoglobin for CO

79
Q

Pulmonary vascular resistance PVR

A

PVR is 16 times less than TPR (total peripheral resistance)

80
Q

perivascular pressure

A

significant effect on pulmonary circulation

can change diamter of the vessle, and thus, resistance

81
Q

wedge pressure

A

left atrial pressure

82
Q

effect of cardiac output on pulmonary vessels

A

increase in CO increase the diameter of pulmonary vessels, decrease the resistance.

83
Q

passive force regulating the pulmonary blood vessel resistance

A
  1. cardiac output

2. lung volume

84
Q

lung vol effect on resistance of alveolar and extra alveolar vessels

A

lung vol increase

  • alveolar vessel pushed to constrict - resistance increase
  • extra alveolar vessel extended - resistance decrease
85
Q

lowest total PVR at…

A

FRC

86
Q

three types of vessels in pulmo circulation

A
  1. large extra pulmonary vessel
  2. arteries andveins
  3. alveola capillaries - periventricular presssure = alveolar pressure
87
Q

alveolar hypoxia effect on pulmo vessel

A

hypoxia inhibit Kv channel -> depolarize -> open Ca++ channel -> sm contract -> vasoconstriction -> blood diverted to normal alveoli

88
Q

global hypoxia effect on pulmo vessel

A

good for only fetus

alveolar capillary constrict -> pulmo hypertension -> right heart failure, pulmonary edema

89
Q

histamin effect on airway and vessel

A

bronchoconstriction

vasodialtion

90
Q

two different receptor

A

alpha-receptor -> constrict

beta2-receptor -> dilate

91
Q

beta2-agonist effect on airway

A

bronchodilation

92
Q

upright position perfusion distribution

A

perfution incresae from top to bottom of the lung

93
Q

anatomical shunt (def. ex.)

A
def - deoxygentated blood mixing with oxygentaed blood 
ex - circulatory vein from lung (BRONCHIAL VEINS) mix into the pulmonary vein 
- coronary vein mix into the left ventricle or atrium (THEBESIAN VEINS)
94
Q

O2 capacity

A

maximum amount of O2 that can be combine with Hb

normal - 20.1mL O2 / 100mL blood

95
Q

PO2 in the mixed blood before entering pulmo capi

A

40mmHg

96
Q

PO2 of 50% oxygen saturation of hemoglobin (P50)

A

used to measure affinity of hemo for ox

97
Q

Boher effect on hemo ox affinity

A

[H+] increase = low pH -> decresae affinity

98
Q

CO2 effect on hemo ox affinity

A

increase in CO2 -> decrease affinity
CO2 directly decrease the affinty
CO2 incease H+ ion

99
Q

temperature effect on hemo ox affinity

A

dec in temp -> increase affinity

inc in temp -> decrease affinity

100
Q

DPG (2,3-diphosphoglycerate) BPG effect on hemo ox affinity

A

increase in [DPG] -> decrease affinity

101
Q

factors influence hemo ox affinity

A
H+
CO2
temp
BPG
when the above increase, affinity decrease
102
Q

CO binding hemo

A

increase affinity of Hb for ox -> not released to tissue

103
Q

hyperbaric oxgen

A

CO poisoning treatment

compete with CO for Hb, high PO2 drive CO away

104
Q

oxidation of Hb

A

methemoglobin

105
Q

3 forms of CO2

A
  1. CO2 - 10%
  2. bicarbonate (HCO3-) - 70%
  3. carbamate (COO-) - 20%
106
Q

Haldane effect

A

deoxygenated hemoglobin at tissue bind CO2 much better, and oxygenated hemoglobin at lung bind CO2 less
- increase in PO2 reduce the combination of both CO2 and H+ with Hb

107
Q

CO poisoning features

A

normal PO2
normal Hb concentration
low O2 concentration

108
Q

factors affecting CO2 binding curve

A
  1. hydrogen ions - increase -> release CO2
  2. temperaure - increase -> release CO2
  3. haldane effect
  4. Bohr effect
109
Q

haldane effect and bohr effect

A

haldane - assist CO2 loading in system capi, and CO2 unloading in the lung
bohr - assist O2 loading in the lung and O2 unloading in the system capi.

110
Q

4 types of hypoxia

A
  1. stagnant hypoxia
  2. anemic hypoxia
  3. histotoxic hypoxia
  4. arterial hypoxia or hypoxemia
111
Q

5 causes of arterial hypoxemia

A
  1. low inspired PO2 (low PIO2)
  2. diffusion limitation
  3. hypoventilation
  4. alveolar ventilation / perfusion mismatch
  5. right to left (venous) shunt
112
Q

judgement paramters

A

PaCO2 and (A-a)PO2

113
Q

anoxia

A

complete absence of oxygen in the tissue

114
Q

stagnant hypoxia

A
O2 delivery to the tissue reduced
blood flow rate to the tissue decreased
arterial PO2 normal
arterial O2 concentration normal
heart failure of vascular diseases that reuce organ perfusion cause this
115
Q

anemic hypoxia

A

O2 delivery to the tissue reduce
reduction in the O2 capacity of the blood
- decrease in Hb concentration or reduced ability of Hb for binding O2
O2 conc. decreased
PO2 normal
cause - deficiency in Hb synthesis or to much degradation, blood loss, CO poisoning, oxidatin of Hb

116
Q

histotoxic hypoxia

A

utilization of ox at the cell blocked
poisons - cyanide or hydrogen sulfide
arterial PO2 normal
arterial O2 conc. nomal

117
Q

arterial hypoxia or hypoxemia

A

reduction of arterial O2 saturation
REDUCED ARTERIAL PO2 (all the other hypoxia has normal PO2)
- 5 causes divided into two categories
1. both alveolar and arterial PO2 value below normal
2. PAO2 normal, PaO2 reduced - create (A-a)PO2 > 0

118
Q

Low inspaired PO2 (caues of arterial hypoxia)

A

high altitude -> PIO2 reduced -> PAO2 reduced -> PaO2 reduced -> carotid body chemoreceptor stimulation -> enhance alveolar ventilation -> decrease in PCO2

119
Q

diffusion limitation (cause of arterial hypoxia)

A

diffusion blcok

120
Q

normoventilation pressure levels

A
PvO2 = 40 mmHg
PvCO2 = 45 mmHg
PAO2 = 100 mmHg
PACO2 = 40 mmHg
PaO2 = 90 mmHg
PaCO2 = 40 mmHg
PIO2 = 150 mmHg
PICO2 = 0 mmHg
121
Q

V(A)/Q

A

highest at the peak of the lung

122
Q

higher VA and lower Q

A

higher PO2 of that region

closer to the fresh air composition

123
Q

V(A)/Q related regions

A
  1. normoventilated regions - V/Q average
  2. hyperventilated regions - V/Q above average
  3. hypoventilated region - V/Q below average
124
Q

increased PaCO2

A

hypoventilation

125
Q

decreased PaCO2

A

Low PIO2 (high altitude)

126
Q

upon 100% ox breathing, PaO2 < 400

A

right to left shunt

127
Q

upon 100% ox breathing, PaO2 > 400

A

diffusion problme or VA/Q mismatch

128
Q

measure diffusion capacity of CO

A

CO diffusion capacity < normal - diffsion problems

CO diffusion capacity = normal - VA/Q misatch