pulmonary 1 Flashcards

1
Q

How many periods does it take to develop the lung?

A

5

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2
Q

What are the periods of lung development?

A

1) Embryonic (weeks 4-7)
2) Pseudoglandular (weeks 5-16)
3) Canalicular (weeks 16-26)
4) Saccular (weeks 26-birth)
5) Alveolar (weeks birth-8 years)

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3
Q

Describe the embryonic stage of lung development.

A

Lung bud-> trachea-> mainstem bronchi-> secondary (lobar) bronchi-> tertiary (segmental) bronchi

Errors at this stage can lead to TE fistula.

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4
Q

Describe the Pseudoglandular stage of lung development.

A

Endodermal tubules-> terminal bronchioles. Surrounded by modest capillary network.

Respiration impossible, incompatible with life.

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5
Q

Describe the Canalicular stage of lung development.

A

Terminal bronchioles-> respiratory bronchioles-> alveolar ducts. Surrounded by prominent capillary network.

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6
Q

Describe the Saccular stage of lung development.

A

Alveolar ducts-> terminal sacs. Terminal sacs separated by primary septae. Pneumocytes develop.

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7
Q

Describe the Alveolar stage of lung development.

A

Terminal sacs-> adult alveoli (d/t secondary septation). In utero, “breathing” occurs via aspiration and expulsion of amniotic fluid-> increase in vascular resistance through gestation. At birth, fluid gets replaced w/ air-> decrease in pulmonary vascular resistance.

At birth: 20-70 million alveoli
By 8 years: 300-400 million alveoli.

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8
Q

What are the 2 congenital lung malformations?

A

1) Pulmonary hypoplasia= poorly developed bronchial tree w/ abnormal histology usually involving the right lung. Associated w/ congenital diaphragmatic hernia, bilateral renal agenesis (Potter Syndrome).

2) Bronchogenic cysts= Caused by abnormal budding of foregut & dilation of terminal or large bronchi. Discrete, round, sharply defined & air-filled densities on CXR. Drain poorly & cause chronic infections.

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9
Q

What are Type I pneumocytes?

A

Thin squamous cells present in the alveoli, functioning in optimal gas diffusion.

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10
Q

Where are Type I pneumocytes found?

A

97% of alveolar surfaces. (line the alveoli)

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11
Q

What is the role & epithelium of Type I pneumocytes?

A

Squamous. Thin for optimal gas diffusion.

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12
Q

How is collapsing pressure calculated?

A

P = (2 x surface tension) / radius.

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13
Q

What is the function of Type II pneumocytes?

A

Secrete pulmonary surfactant –> decrease alveolar surface tension; prevent alveolar collapse, decrease lung recoil & increase compliance.

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14
Q

What type of cells, histologically, are Type II pneumocytes?

A

Cuboidal.

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15
Q

Do Type II cells originate from Type I cells, or are Type II cells progenitors for Type I cells?

A

Type II cells are progenitors for Type I cells. Type II cells can also give rise to other Type II cells.

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16
Q

When do Type II cells proliferate?

A

In lung damage.

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17
Q

What is the Law of Laplace?

A

As the radius decreases upon expiration, alveoli have an increased tendency to collapse.

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18
Q

What does ‘atelectasis’ mean, and how is it caused?

A

DEFINITION collapse of alveoli.
CAUSES obstruction, compression, or contraction –> damage to Type II pneumocytes –> loss of surfactant.

Even reinflation may not return full function due to the loss of surfactant.

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19
Q

What is surfactant, chemically?

A

A complex mix of lecithins, most importantly dipalmitoylphosphatidylcholine.

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20
Q

What are Clara (Club) cells?

A

Nonciliated, columnar cells with secretory granules.

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21
Q

What do Clara cells secrete?

A

A “watery” component of surfactant.

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22
Q

What are the functions of Clara cells?

A

To secrete a component of surfactant, to degrade toxins, and to act as reserve cells.

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23
Q

When does surfactant synthesis begin?

A

Around week 26 of gestation.

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24
Q

When are mature levels of surfactant reached?

A

Around week 35 of gestation.

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25
Q

If a child is born premature, is it likely that they will produce sufficient levels of surfactant?

A

No.

At risk of developing atelectasis.

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26
Q

What measurement indicates if a fetus has mature lung function?

A

Lecithin : sphingomyelin above 2. This can be measured in the amniotic fluid.

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27
Q

What is the cause of neonatal respiratory distress syndrome?

A

Inadequate surfactant –> increased surface tension –> alveolar sac collapse after expiration –> formation of hyaline membranes.

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28
Q

What lecithin:sphingomyelin ratio in amniotic fluid is predictive of neonatal RDS?

A

Ratio <1.5.

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29
Q

With what is neonatal RDS associated?

A

Prematurity: adequate surfactant levels are not reached until week 35.
C-section: d/t lack of release of stress-induced steroids (fetal glucocorticoids) –> no increased synthesis of surfactant.
Maternal diabetes: increased fetal glucose-> increased fetal insulin-> decreased surfactant levels.

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30
Q

What are the clinical features of neonatal RDS?

A

Increasing respiratory effort after birth, tachypnea with use of accessory muscles, grunting, hypoxemia with cyanosis, CXR showing “ground-glass” appearance of lung.

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31
Q

What are the complications of neonatal RDS?

A

(1) Persistently low O2 tension –> hypoxemia –> increased risk of PDA, necrotizing enterocolitis.

(2) Therapeutic supplemental oxygen–> increased risk of free radical injury (O2 can be toxic!) –> “RIB”.

R= Retinopathy of prematurity
I= Intraventricular hemorrhage
B= Bronchopulmonary dysplasia.

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32
Q

What is the treatment for neonatal RDS?

A

Maternal steroids before birth; artificial surfactant for infant.

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33
Q

What is the order of structures in the Respiratory tree?

A

Trachea-> bronchi-> bronchioles-> terminal bronchioles-> respiratory bronchioles-> alveolar sacs.

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34
Q

What does smoking do to the epithelial lining of the trachea?

A

Pseudo stratified ciliated columnar-> squamous (via metaplasia & now sputum cannot be cleared).

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35
Q

Where is the highest & lowest resistance in the Respiratory Tree?

A

Highest= medium-size bronchi (turbulent airflow).
Lowest= terminal bronchioles (high CSA).

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36
Q

What is the conducting zone?

A

The larger airways that warm, humidify, and filter air without participating in gas exchange (i.e. anatomic dead space).

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37
Q

What are the large airways of the conducting zone?

A

Nose, pharynx, trachea, bronchi.

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38
Q

What are the small airways of the conducting zone?

A

Bronchioles and terminal bronchioles (large #’s in parallel-> least airway resistance).

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39
Q

To what level of the conducting zone will cartilage and goblet cells extend?

A

Bronchi.

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40
Q

To what level of the conducting zone will pseudostratified ciliated columnar cells extend?

A

Terminal bronchioles.

Clear mucus & debris from lungs (mucociliary escalator).

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41
Q

To what level of the conducting zone will smooth muscle cells extend?

A

Terminal bronchioles.

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42
Q

What is the respiratory zone?

A

The airways participating in gas exchange.

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43
Q

What are the airways of the respiratory zone?

A

Lung parenchyma; respiratory bronchioles, alveolar ducts, alveoli.

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44
Q

What is the histology of the respiratory bronchioles?

A

Cuboidal cells.

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45
Q

What is the histology of the alveoli?

A

Simple squamous cells.

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46
Q

You see simple squamous cells on a histology slide. From what level of the respiratory system is the slide?

A

Alveoli or alveolar ducts.

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47
Q

You see pseudostratified ciliated columnar cells on a histology slide. From what level of the respiratory system is the slide?

A

Terminal bronchioles or above.

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48
Q

You see cartilage on a histology slide. From what level of the respiratory system is the slide?

A

Bronchi or above.

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49
Q

You see goblet cells on a histology slide. From what level of the respiratory system is the slide?

A

Bronchi or above.

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50
Q

You see cuboidal cells on a histology slide. From what level of the respiratory system is the slide?

A

Respiratory bronchioles.

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51
Q

Are cilia present in the respiratory zone?

A

No.

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52
Q

Where in the respiratory system may macrophages be found?

A

Alveoli-> clear debris & participate in the immune response.

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53
Q

Which lung has three lobes?

A

Right lung.

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54
Q

Which lung has two lobes?

A

Left lung; in place of the middle lobe, the lung accommodates the space necessary for the heart.

Left Lung has Less Lobes.

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55
Q

Which lung has a lingula?

A

Left lung.

Lingula is a tongue shaped portion of the left lung.

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56
Q

Which lung is the more common site for inhaled foreign bodies and why?

A

Right lung; right main stem bronchus is wider and more vertical.

“Swallow a bite, goes down the right.”

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57
Q

The relation of the pulmonary artery to the bronchus at each lung hilum is described by?

A

RALS: Right Anterior; Left Superior.

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58
Q

If a patient aspirates a peanut while upright, where in the lungs will it be found?

A

Inferior (AKA basilar) portion of the right inferior lobe.

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59
Q

If a patient aspirates a peanut while supine, where in the lungs will it be found?

A

Superior portion of the right inferior lobe OR posterior portion of the right upper lobe.

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60
Q

What structures perforate the diaphragm at T8, T10, and T12, respectively?

A

T8= IVC

T10= esophagus, vagus nerve (CN 10)

T12= aortic (red), thoracic duct (white), azygous vein (blue).

“I 8 10 Eggs At 12.”

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61
Q

What is the innervation of the diaphragm?

A

C3, C4, C5 (phrenic nerve).

–C3, 4, and 5 keep the diaphragm alive–

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62
Q

Where might pain from the diaphragm be referred?

A

Shoulder (C5), trapezius ridge (C3, C4).

63
Q

Name the bifurcations for the common carotid, trachea & abdominal aorta.

A

C4= common carotid

T4= trachea

L4= abdominal aorta.

“biFOURcates.”

64
Q

In quiet breathing, what muscle is responsible for inspiration?

A

Diaphragm.

65
Q

In quiet breathing, what muscle is responsible for expiration?

A

None (passive process).

66
Q

In exercise, what muscles are responsible for inspiration?

A

External intercostals, scalenes, sternocleidomastoid.

–inSpiration: external, Scalene, Scm–

67
Q

In exercise, what muscles are responsible for expiration?

A

Rectus abdominus, internal obliques, external obliques, transversus abdominis, internal intercostals.

68
Q

What is the IRV?

A

Inspiratory Reserve Volume: the air that can still be breathed in after normal inspiration.

69
Q

What is the TV?

A

Tidal Volume: air that moves into lung with each quiet inspiration.

70
Q

What is the normal TV?

A

500.

71
Q

What is ERV?

A

Expiratory Reserve Volume: air that can still be breathed out after normal expiration.

72
Q

What is RV?

A

Residual Volume: the air in lung after maximal expiration.

73
Q

Which lung volume measurement cannot be read by spirometry?

A

RV (residual volume).

74
Q

How is IC calculated?

A

Inspiratory Capacity = IRV + TV.

75
Q

How is FRC calculated?

A

Functional Residual Capacity = RV + ERV.

Volume of gas in lungs after normal expiration; cannot be measured on spirometry.

76
Q

How is VC calculated?

A

Vital Capacity = IRV + TV + ERV.

Maximum volume of gas that can be expired after a maximal inspiration.

77
Q

How is TLC calculated?

A

Total Lung Capacity = IRV + TV + ERV + RV.

Volume of gas present in the lungs after a maximal inspiration; cannot be measured on spirometry.

78
Q

What is physiologic dead space?

A

Anatomic dead space of conducting airways plus alveolar dead space (capable of gas exchange but no exchange occurs) in alveoli; volume of inspired air that does NOT take place in gas exchange.

79
Q

How is physiologic dead space calculated?

A

Vd = Vt x [(PaCO2 - PeCO2) / PaCO2].

“Taco, PAco, PEco, PAco.”

80
Q

What is the largest contributor of alveolar dead space?

A

Apex of the lung d/t not enough blood flow.

81
Q

When is the physiologic dead space = anatomic dead space?

A

Normal lungs.

82
Q

When is the physiological dead space greater than the anatomic dead space?

A

Lung diseases w/ V/Q defects.

83
Q

What is pathologic dead space?

A

When part of the respiratory zone becomes unable to perform in gas exchange. Ventilation but no perfusion.

84
Q

Equation for Minute Ventilation

A

Total volume of gas entering lungs per minute.

*Ve= VtRR.

85
Q

Equation for Alveolar Ventilation

A

Volume of gas per unit of time that reaches alveoli.

*Va= (Vt-Vd)RR.

86
Q

What are the normal values for RR, Vd & Vt?

A

RR= 12-20 breaths/min

Vd= 150 mL/breath

Vt= 500 mL/breath.

87
Q

There is a tendency for the lungs to _____ _____ and chest wall to ____ ______.

A

Collapse inward; spring outward.

88
Q

At FRC, what is the system pressure?

A

Atmospheric; the inward pull of the lung is balanced by the outward pull of the chest wall.

89
Q

What determines the combined volume of the chest wall and lungs?

A

Their elastic properties.

90
Q

At FRC, what is the airway pressure?

A

0.

91
Q

At FRC, what is the alveolar pressure?

A

0.

92
Q

At FRC, what is the intrapleural pressure?

A

Negative (This prevents pneumothorax). PVR is at a minimum.

93
Q

What is compliance?

A

The change in lung volume for a given change in pressure.

[C= V/P].

**Higher compliance= lung easier to fill.

**Lower compliance= lung hard to fill.

94
Q

In what processes does compliance decrease?

A

Pulmonary fibrosis, pneumonia, pulmonary edema.

**FRC decreases b/c the lungs are now exerting more inward collapsing pressure.

95
Q

What are the causes of pulmonary edema?

A

HEMODYNAMIC: increased vascular pressure, decreased oncotic pressure.

MICROVASCULAR DAMAGE: infection, ARDS, DIC, UNCLEAR: neurogenic, high altitude.

96
Q

In what processes does compliance increase?

A

Emphysema, normal aging.

**FRC increases because the lungs don’t do a good job of resisting the outward pull of the chest wall.

97
Q

Does surfactant increase or decrease compliance?

A

Increase.

98
Q

What happens to intra-thoracic volume when the lung collapses?

A

Increases d/t unopposed chest expansion.

99
Q

Discuss PVR for extra alveolar vessels & alveolar vessels at RV & TLC.EDIT?UNCLEAR

A

RV= extra alveolar vessels have highest PVR.

TLC= alveolar vessels have highest PVR.

100
Q

What are the subunits of hemoglobin?

A

4 polypeptide subunits: 2 alpha, 2 beta.

101
Q

Which form of hemoglobin has a low affinity for oxygen?

A

T (taut; deoxygenated)-> promotes release/unloading of O2.

–Taut in Tissues–

102
Q

Which form of hemoglobin has a high affinity for oxygen?

A

R (relaxed; oxygenated).

–Relaxed in Respiratory–

103
Q

Hemoglobin exhibits ____ cooperativity and negative _____.

A

Positive cooperativity; negative allosterity.

104
Q

What are the subunits of fetal hemoglobin (HbF)?

A

2 alpha, 2 gamma.

105
Q

HbF has a lower affinity for _____ than adult hemoglobin, allowing it a _____ affinity for O2.EDIT?/unclear

A

Lower.

106
Q

What promotes the release/unloading of O2?

A

T (taut; deoxygenated)

Taut in Tissues

107
Q

Which form of hemoglobin has a high affinity for oxygen?

A

R (relaxed; oxygenated)

Relaxed in Respiratory

108
Q

What type of cooperativity does hemoglobin exhibit?

A

Positive cooperativity

109
Q

What type of allosterity does hemoglobin exhibit?

A

Negative allosterity

110
Q

What are the subunits of fetal hemoglobin (HbF)?

A

2 alpha, 2 gamma

111
Q

What is the affinity of HbF for 2,3-BPG compared to adult hemoglobin?

A

HbF has a lower affinity for 2,3-BPG, allowing it a higher affinity for O2

This drives diffusion of O2 across the placenta from mother to fetus.

112
Q

Which binds oxygen better: adult or fetal hemoglobin?

A

Fetal hemoglobin

113
Q

What factors favor the taut form over the relaxed form of hemoglobin?

A

Cl-, H+, CO2, 2,3-BPG & increased temperature

114
Q

What does the taut form of hemoglobin favor?

A

Unloading of oxygen into tissues

115
Q

How does the dissociation curve shift with the taut form?

A

Shifts to the right

116
Q

Why do HbS molecules sickle in sickle cell anemia?

A

HbS allows hydrophobic interaction among hemoglobin molecules, leading to polymerization of HbS and sickling in hypoxia

117
Q

What effect do modifications to hemoglobin have on O2 saturation and content?

A

Decreased O2 saturation and content, leading to tissue hypoxia

118
Q

What is methemoglobin?

A

An oxidized form of hemoglobin (Fe2+ –> Fe3+) that does not bind O2 as readily

119
Q

What is a ferric ion?

A

Fe3+

120
Q

How is iron in hemoglobin normally found?

A

Fe2+ (ferrous; reduced state)

Fe2+ binds O2

121
Q

What does methemoglobin have an increased affinity for?

A

Cyanide

122
Q

How does Methemoglobinemia present?

A

Cyanosis & chocolate-colored blood

123
Q

What effect do nitrates have on iron?

A

They oxidize Fe2+ to Fe3+

Note: There will be normal readings of PaO2, but decreased levels of Hb O2 saturation.

124
Q

What is the use of nitrates followed by thiosulfate?

A

Induced methemoglobinemia for treatment of cyanide poisoning

125
Q

How do you treat methemoglobinemia?

A

Methylene blue & Vitamin C

METHemoglobin needs METHylene blue.

126
Q

What is carboxyhemoglobin?

A

Form of hemoglobin bound to CO in place of O2

127
Q

What is the affinity of CO for hemoglobin compared to O2?

A

200X that of O2

128
Q

How does the oxygen-hemoglobin curve shift in carboxyhemoglobinemia?

A

Causes a decrease in O2-binding capacity with a left shift

This decreases O2 unloading in tissues.

129
Q

How are PaO2, percent saturation, and O2 content changed in carboxyhemoglobinemia?

A

PaO2: normal, percent saturation: decreased, O2 content: decreased

130
Q

What shape does the oxygen-hemoglobin dissociation curve have?

A

Sigmoidal due to positive cooperativity

A tetrameric hemoglobin molecule can bind 4 oxygen molecules and has a higher affinity for each subsequent oxygen molecule bound.

131
Q

What shape does the oxygen-myoglobin dissociation curve have? Add picture

A

Hyperbolic due to monomeric nature that does not show positive cooperativity

132
Q

What does a right shift of the oxygen-hemoglobin dissociation curve denote?

A

Decreased affinity of hemoglobin for O2, indicating unloading of O2 to tissue

133
Q

What causes a right shift of the oxygen-hemoglobin dissociation curve?

A

Acid (H+), CO2 (hypoxemia), CHF, chronic lung disease, exercise, BPG (2,3-BPG), temperature

134
Q

What happens when there is a left shift physiologically?

A

Decreased O2 unloading leads to renal hypoxia, increased EPO synthesis, and compensatory erythrocytosis

135
Q

Which direction is the HbF curve shifted and why?

A

Left: fetal hemoglobin has a greater affinity for O2

136
Q

Describe the Hb concentration, O2 saturation of Hb, Dissolved O2 (PaO2) & total O2 content for CO poisoning.(why total 02 content- EDIT/UNCLEAR)

A

Normal Hb concentration, decreased Hb saturation, normal PaO2, decreased total O2 content

137
Q

Describe the Hb concentration, O2 saturation of Hb, Dissolved O2 (PaO2) & total O2 content for anemia.

A

Decreased Hb concentration, normal Hb saturation, normal PaO2, decreased total O2 content

138
Q

Describe the Hb concentration, O2 saturation of Hb, Dissolved O2 (PaO2) & total O2 content for polycythemia.

A

Increased Hb concentration, decreased Hb saturation, normal PaO2, increased total O2 content

139
Q

What happens when there is a decrease in Hb to O2 content, O2 saturation & PaO2?

A

Decrease in O2 content of the blood, but no change in O2 saturation & PaO2

140
Q

Does a decrease in PAO2 cause vasoconstriction or vasodilation?

A

Hypoxic vasoconstriction; blood moves away from poorly ventilated regions of the lung to well-ventilated regions

141
Q

How can diffusion across perfusion limited lung membranes increase?

A

If blood flow increases

142
Q

What is the equation for diffusion?

A

Vgas = A x Dk x (P1-P2)/T

143
Q

How does the diffusion equation change in emphysema?

A

Area decreases

144
Q

How does the diffusion equation change in pulmonary fibrosis?

A

Thickness increases

145
Q

In normal, healthy lungs, is the circulation perfusion or diffusion limited?

A

Perfusion limited

146
Q

In perfusion limited circulation, when does gas equilibrate?

A

Early along the length of the capillary

147
Q

In diffusion limited circulation, when does gas equilibrate?

A

At no point; gas does not equilibrate by the time the blood reaches the end of the capillary

148
Q

Is O2 in normal health perfusion or diffusion limited?

A

Perfusion limited

149
Q

Is O2 in emphysema or fibrosis perfusion or diffusion limited?

A

Diffusion limited

150
Q

Is CO2 perfusion or diffusion limited?

A

Perfusion limited

151
Q

Is N2O perfusion or diffusion limited?

A

Perfusion limited

152
Q

Is carbon monoxide perfusion or diffusion limited?

A

Diffusion limited

153
Q

What is DLCO?

A

The extent to which O2 passes from air sacs of lungs into the blood

154
Q

What is the flow of events in COPD?

A

Lungs encounter a decrease in PAO2, leading to chronic pulmonary vasoconstriction, chronic pulmonary HTN, cor pulmonale, and subsequent right ventricular failure