Lung (3) Flashcards

1
Q

O2 consumption

A

240 - 280 ml/min

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2
Q

Co2 Production

A

190 - 220 ml/min

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3
Q

Overall water loss per day from breathing

A

250 ml/day

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4
Q

Layers of Mucous

A
  • Inner Sol layer (Cilia)
  • Outer gel layer
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5
Q

Clearance of particles

A
  • Impaction: Nasal cavity
  • Sedimentation: lower airways
  • Diffusion: alveoli (macrophage clearance)
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6
Q

Lung metabolic function

A
  • Renin: Angiotensinogen to Ang1
  • ACE: Ang1 to Ang 2
  • ACE2: Ang2 to Ang 1-7
    (viruses use ACE2 to enter)
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7
Q

Dichotomic divisions

A
  • Conducting zone (1-16) : Dead space
  • Respiratory zone (17-23) : alveolar space
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8
Q

Physiological Dead space

A

Sum of anatomical dead space (150ml) and Functional/Alveolar dead space (negligible)

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9
Q

Functional Dead space

A

Space of the ventilated alveoli that does not participate in gas exchange

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10
Q

Alveolar cells

A
  • Type-1: Squamous for gas exchange
  • Type-2: Smaller, produce surfactant
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11
Q

Alveolar Ventilation

A

4900 ml/min

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12
Q

Dynamic lung volumes

A

Related to rate at which air flows in/out of lungs

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13
Q

Static lung volumes

A

Not affected by the rate of air in/out of lungs

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14
Q

Tidal Volume (TV)

A

500 ml
Amount of air entering/leaving the lungs without extra effort

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15
Q

Inspiratory Reserve Volume (IRV)

A

3100 ml (1900 ml F)
Max inspiration above tidal volume

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16
Q

Expiratory Reserve Volume (ERV)

A

1200 ml (800 ml F)
Volume exhaled above tidal volume

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17
Q

Residual Volume (RV)

A

1200 ml (1000 ml F)
Air remaining in the lungs after complete exhalation

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18
Q

Inspiratory Capacity (IC)

A

3600ml (2400 ml F)
Largest amount that can be inhaled
(TV+IRV)

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19
Q

Functional Residual Capacity (FRC)

A

2400 ml (1800 ml F)
Volume after normal expiration

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20
Q

Vital Capacity (VC)

A

4800 ml (3200 ml F)
Entire volume that can be maximally inhaled and exhaled

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21
Q

Total Lung capacity (TLC)

A

6000 ml (4200 ml F)
All of the lung volume
(VC + RV)

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22
Q

How do we determine FRC

A
  • Helium Dilution method
  • Plethysmography
  • Spiroscope
  • Clinical spirogram
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23
Q

Helium Dilution method

A

Closed circuit with spirometer and patient asked to breathe until helium is equilibrated
c1 * v1 = c2 * (v1+v2)
v2 = FRC

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24
Q

Plethysmography

A

Air tight cabin with shutter, after expiration patient is asked to do a forceful inspiration while shutter is closed. Chest extends and pressure is measured.

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25
Q

Spiroscope

A

Measures gas flow
V = Q * T

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26
Q

Clinical Spirogram

A

To measure forced expiratory volume in 1 second
- Ask patient for max inh & ex. (VC)
- Tiffeneau-index: FEV / VC
How much of the VC can be exhaled in 1 second, should be 80% normally

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27
Q

How to determine Dead space

A
  • O2 inh & N2 exh.
  • pCO2 measurement
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28
Q

Dead space, O2 inh & N2 exh.

A

1) Patient inhales pure oxygen
2) During exhalation N2 conc is detected
3) As long as person is exhaling from dead space no N2 is detected
4) If volume where N2 appears is known, V of dead space can be calculated

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29
Q

Relationship bw Alveolar ventilation and pCO2

A

Inverse hyperbolic

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30
Q

PaCO2

A

40 mmHg

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31
Q

Effects of ventilation on PaCO2

A
  • Hyperventilation: PaCO2 < 40 mmHg (hypocapnia)
  • Hypoventilation: PaCO2 > 40 mmHg (hypercapnia)
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32
Q

What keeps alveoli open in resting position?

A

Negative pressure of intrapleural space counteracts retraction tendency
Ppl = - 5 cmH2O

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33
Q

Transmural Pressure (Ptm)

A

Pressure difference bw Pa and Ppl
Ptm = Pa - Ppl
= 0 - (-5) = + 5 cmH2O

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34
Q

Surfactant

A
  • Composed of lipids and proteins
  • Reduces surface tension
  • Reduces cohesion force of H2O
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35
Q

Surfactant and Work of breathing

A

Reduced work
- W = P * V
- Surfactant lowers retraction tendency
- Less work needed

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36
Q

Surfactant and Alveoli collapse

A
  • Smaller radius, higher pressure (Laplace law)
  • More surfactant in smaller alveoli to reduce pressure by surface tension
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37
Q

Surfactant and Pulmonary Edema

A
  • Retraction tend. in alveoli creates suction force on capillaries causing fluid movement from cap to interstitium. (Pulmonary edema)
  • Surfactant reduces retraction tend., less suction force, no edema
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38
Q

Hysteresis

A
  • Difference in curves of expiration and inspiration
  • Caused by surfactant, less compliance on inspiration since more surface tension due to smaller alveoli
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39
Q

Compliance

A

How volume changes as a result of pressure change
C = V / P
- Compliance of the lung is high

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40
Q

Compliance of Lung

A

Ptm = Pa - Ppl
0.2 L/cmH2O

41
Q

What other pressure can be measured to tell us Ppl

A

Pesophegeal
Due to sphincters

42
Q

Fibrosis

A
  • Less elastic fibers
  • Less lung compliance
  • Difficult breathing
43
Q

Emphysema

A
  • Walls of lung more flexible
  • Increased lung compliance
  • Exhaling will require more effort due to less retraction tendency
44
Q

Compliance of the Chest

A

Ptm = Ppl - Pb
= 0.2 L/mmH2O

45
Q

Compliance of Respiratory system (Lungs + Chest)

A

Ptm = Pa - Pb
= 0.1 L/mmH2O

46
Q

Equal Pressure Point (EPP)

A

When Pa = Ppl

47
Q

Respiratory membrane layers

A

1 um thick
1) Surfactant layer
2) Alveolar epithelium
3) Epithelial basement mem.
4) Interstital space
5) Capillary basement layer
6) Capillary endothelium

48
Q

pO2 Alveolus, Venous, Arterial

A
  • Alveolus: 100 mmHg
  • Capillary: 40 mmHg
  • Arterial: 95 mmHg
49
Q

pCO2 Alveolus, Venous, Arterial

A
  • Alveolus: 40 mmHg
  • Capillary: 46 mmHg
  • Arterial: 40 mmHg
50
Q

Why is arterial PO2 not 100mmHg but only 95mmHg?

A
  • Mixing with blood from the bronchial system (lung b.s)
  • Ventilation-perfusion mismatch due to gravitation
51
Q

Why does Oxygen have a 10x larger pressure gradient than CO2

A

O2 has a lower diffusion capacity meaning it needs a very larger pressure gradient to drive the diffusion

52
Q

2 types of gas exchange

A
  • Diffusion limited gas exchange
  • Perfusion limited gas exchange
53
Q

What law describes solubility of a gas?

A

Henry’s Law

54
Q

Total blood volume in Pulmonary circulation

A

500 ml
(10% of total)

55
Q

Right ventricle pressure

A

25 mmHg

56
Q

Pulmonary Artery pressure

A

25 / 9
= 14 mmHg

57
Q

Pulmonary Capillary pressure

A

10 mmHg

58
Q

Pulmonary Vein pressure

A

9 mmHg

59
Q

Ppl at apex of Lung

A

More negative compared to base

60
Q

Apex of Lung R, P, Q

A
  • High resistance
  • Low pressure
  • Low flow
61
Q

Base of Lung R, P, Q

A
  • Low resistance
  • High pressure
  • High flow
62
Q

Ventilation / Blood flow ratio

A
  • Higher: More ventilation vs flow (apex)
  • Lower: More flow vs ventilation (base)
    Due to Shunt and Dead space
63
Q

Physically dissolved O2

A

3 mlo2/L of blood (100mmHg)
Body uses 250 ml/min

64
Q

O2 binding capacity of hemoglobin

A

2.3 mmol/L

65
Q

How much O2 in hemoglobin at 100% O2 saturation

A

206 ml O2/L

66
Q

Effect of CO2 on Hb affinity

A
  • Increase in H+
  • Lower O2 affinity
  • Right-shift
67
Q

Effect of Temperature on Hb affinity

A
  • Higher temp denatures bond bw Hb and O2
  • Lower O2 affinity
  • Right-shift
68
Q

CO2 tension

A

24 ml/L (40 mmHg)
(= carbamino form)

69
Q

Total CO2 in blood

A

480 ml/L

70
Q

O2 conc. in Blood Arteries & Veins

A
  • Artery: 200 ml/L
  • Vein: 150 ml/L
71
Q

High HCO3- effect on RBC

A

RBC swell due to Cl-/HCO3- exchanger

72
Q

Bohr effect

A

Effect of CO2 on affinity of Hb to O2

73
Q

Haldane effect

A

Effect of O2 on the affinity of Hb for CO2

74
Q

Types of Hypoxia

A
  • Hypoxic Hypoxia
  • Anemic Hypoxia
  • Circulatory Hypoxia
  • Histotoxic Hypoxia
75
Q

Hypoxic Hypoxia

A

Due to low O2 levels

76
Q

Anemic Hypoxia

A

Due to less functional Hb

77
Q

Circulatory Hypoxia

A

Due to Low perfusion (Q)
(blockage)

78
Q

Histotoxic Hypoxia

A

Tissue is unable to use O2
(cyanide poisons)

79
Q

Upright position

A
  • 0.5 - 1 L of blood acc. in lower
  • Decreased venous return
  • Decreased CO (heterometric)
  • Drop in MABP
80
Q

Mechanisms to restore BP in upright position

A
  • Decreased Vagal tone
  • Increased release of Sympathetic agonists
81
Q

pO2 and pCO2 in Exercise

A

DO NOT CHANGE

82
Q

Effects during Exersise

A
  • Rise in venous pCO2
  • Increased blood flow
  • AVDO2 increases
  • Lower oxygen affinity
  • Lower TPR (vasodilation)
83
Q

Anaerobic Threshold

A

The level of exercise at which sustained metabolic lactic acidosis begins

84
Q

What is Max CO?

A

30 L/min
(can not increase further)

85
Q

Where is phrenic nerve exit from spinal cord

A

C4

86
Q

What controls breathing (4)?

A
  • Respiratory control centers
  • Central chemoreceptors
  • Peripheral chemoreceptors
  • Mechanoreceptors
87
Q

Respiratory Control Centers + Place + Nuclei

A
  • In medulla
  • Ventilatory pattern generator
  • Integrator
  • Dorsal, Ventral, Pontine Resp. groups
88
Q

Dorsal respiratory group (DRG)

A
  • Cells in NTS
  • Dorsomedial
  • Afferent input from CN IX, X
89
Q

Ventral respiratory group (VRG)

A
  • Ventrolateral
  • Nucleus Retrofecialis (exh)
  • Nucleus Retroambiguous (inh)
  • Nucleus Para-ambiguous (both)
90
Q

What controls basic rhythm of breathing

A

VRG
Botzinger and Pre-Botzinger complexes

91
Q

3 Respiratory centers of brainstem

A
  • Medullary center (V/D/P RG)
  • Apneustic center (pontine)
  • Pneumotaxic center (pontine)
92
Q

Apneustic center

A

Stimulation of prolonged inspiration

93
Q

Pneumotaxic center

A

Turns off inspiration to prevent over inflation
(can live without this center)

94
Q

Pacemaker Theory

A

Cells of Botzinger complex in VRG

95
Q

Central Chemoreceptors

A
  • In CSF behind BBB
  • Sensitive to pCO2 changes
  • CO2 can pass BBB
96
Q

Peripheral Chemoreceptors

A
  • In Carotid and Aortic bodies
  • Sensitive to pO2 drop, pCO2 rise, pH drop, K+ rise
97
Q

Why does K+ effect any of this?

A

Higher E.C K+ causes H+ to enter cells to compensate for the loss of positive charge
= Acidic environment inside cells
= Acidosis

98
Q

Mechanoreceptors in Lungs

A
  • Stretch receptors
  • Irritant receptors
  • Juxtacapillary receptors
99
Q

Hering-Breuer Reflex

A

Initiation of expiration when the Lungs are stretched