Lung (3) Flashcards

(101 cards)

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
The air leaving is more moist than air going in

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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
Spiroscope
Measures gas flow V = Q * T
26
Clinical Spirogram
To measure forced expiratory volume in 1 second - Ask patient for max inh & ex. (VC) - Tiffeneau-index: FEV(1s) / VC How much of the VC can be exhaled in 1 second, should be 80% normally
27
How to determine Dead space
- O2 inh & N2 exh. - pCO2 measurement
28
Dead space, O2 inh & N2 exh.
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
29
Relationship bw Alveolar ventilation and alveolar pCO2
Inverse hyperbolic
30
CO2 production resting vs exercise
- Rest: 250ml/min - Exercise: 750ml/min
31
Effects of ventilation on PaCO2
- Hyperventilation: PaCO2 < 40 mmHg (hypocapnia) - Hypoventilation: PaCO2 > 40 mmHg (hypercapnia)
32
What keeps alveoli open in resting position?
Negative pressure of intrapleural space counteracts retraction tendency Ppl = - 5 cmH2O
33
Transmural Pressure (Ptm)
Pressure difference bw Pa and Ppl Ptm = Pa - Ppl = 0 - (-5) = + 5 cmH2O
34
Surfactant
- Composed of lipids and proteins - Reduces surface tension - Reduces cohesion force of H2O
35
Surfactant and Work of breathing
Reduced work - W = P * V - Surfactant lowers retraction tendency - Less work needed
36
Surfactant and Alveoli collapse
- Smaller radius, higher pressure (Laplace law) so air will flow and collect in larger alveoli - More surfactant (or higher conc) in smaller alveoli to reduce pressure by surface tension
37
Surfactant and Pulmonary Edema
- 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
38
Hysteresis
- Difference in curves of expiration and inspiration (from collapsed state) - Caused by surfactant, less compliance on inspiration since more surface tension due to smaller alveoli & surfactant not being spread
39
Compliance
How volume changes as a result of pressure change C = V / P - Compliance of the lung is high
40
Compliance of Lung
Ptm = Pa - Ppl 0.2 L/cmH2O
41
What other pressure can be measured to tell us Ppl
Esophageal Pressure Due to sphincters
42
Fibrosis
- Less elastic fibers - Less lung compliance - Difficult breathing
43
Emphysema
- Walls of lung more flexible - Increased lung compliance - Exhaling will require more effort due to less retraction tendency
44
Compliance of the Chest
Ptm = Ppl - Pb = 0.25 L/cmH2O
45
Compliance of Respiratory system (Lungs + Chest)
Ptm = Pa - Pb = 0.1 L/cmH2O
46
Equal Pressure Point (EPP)
When Pa = Ppl (forced expiration)
47
Respiratory membrane layers
1 μm thick 1) Surfactant layer 2) Alveolar epithelium 3) Epithelial basement mem. 4) Interstital space 5) Capillary basement layer 6) Capillary endothelium
48
pO2 Alveolus, Venous, Arterial
- Alveolus: 100 mmHg - Capillary: 40 mmHg - Arterial: 95 mmHg
49
pCO2 Alveolus, Venous, Arterial
- Alveolus: 40 mmHg - Capillary: 46 mmHg - Arterial: 40 mmHg
50
Why is arterial PO2 not 100mmHg but only 95mmHg?
- Mixing with blood from the bronchial system (lung b.s) - Ventilation-perfusion mismatch due to gravitation
51
Why does Oxygen have a 10x larger pressure gradient than CO2
O2 has a lower diffusion capacity meaning it needs a very larger pressure gradient to drive the diffusion
52
2 types of gas exchange
- Diffusion limited gas exchange - Perfusion limited gas exchange
53
What law describes solubility of a gas?
Henry's Law
54
Total blood volume in Pulmonary circulation
500 ml (10% of total)
55
Right ventricle pressure
25 mmHg
56
Pulmonary Artery pressure
24 / 9 = 14 mmHg
57
Pulmonary Capillary pressure
~10 mmHg
58
Pulmonary Vein pressure
~9 mmHg
59
Ppl at apex of Lung
More negative compared to base
60
Apex of Lung R, P, Q
- High resistance - Low pressure - Low flow
61
Base of Lung R, P, Q
- Low resistance - High pressure - High flow
62
Ventilation / Blood flow ratio
- Higher: More ventilation vs flow (apex) - Lower: More flow vs ventilation (base) Due to Shunt and Dead space (pathologies)
63
Physically dissolved O2
3 ml/L of blood (100mmHg) Body uses ~250 ml/min
64
O2 binding capacity of hemoglobin
2.3 mmol/L 1mol Hb can bind 4 moles of O2
65
How much O2 in hemoglobin at 100% O2 saturation
206 ml/L
66
Effect of CO2 on Hb affinity
- Increase in H+ - Carbamino-Hb - Lower O2 affinity - Right-shift
67
Effect of Temperature on Hb affinity
- Higher temp denatures bond bw Hb and O2 - Lower O2 affinity - Right-shift
68
2,3-BPG effect on Hb affinity
Lowers affinity
69
CO2 transport forms
- Physically dissolved form (24ml/L) - Carbamino form (24ml/L) - Bicarbonate (432ml/L)
70
Total CO2 in blood
480 ml/L
71
O2 conc. in Blood Arteries & Veins
- Artery: 200 ml/L - Vein: 150 ml/L
72
High HCO3- effect on RBC
RBC swell due to Cl-/HCO3- exchanger
73
Bohr effect
Effect of CO2 on affinity of Hb to O2 - H+ can cause dissociation - All related to carbonic anhydrase
74
Haldane effect
Effect of O2 on the affinity of Hb for CO2 (opposite of Bohr)
75
Types of Hypoxia
- Hypoxic Hypoxia - Anemic Hypoxia - Circulatory Hypoxia - Histotoxic Hypoxia
76
Anemic Hypoxia
Due to less functional Hb
77
Circulatory Hypoxia
Due to Low perfusion (Q) (blockage)
78
Histotoxic Hypoxia
Tissue is unable to use O2 (cyanide poisons)
79
Upright position
- 0.5 - 1 L of blood acc. in lower - Decreased venous return - Decreased CO (heterometric) - Drop in MABP
80
Mechanisms to restore BP in upright position
- Decreased Vagal tone - Increased release of Sympathetic agonists
81
pO2 and pCO2 in Exercise
DO NOT CHANGE
82
Effects during Exercise
- Rise in venous pCO2 - Increased blood flow - AVDO2 increases (60 to 180 now) - Lower oxygen affinity (right shift) - Lower TPR (vasodilation)
83
Anaerobic Threshold
The level of exercise at which sustained metabolic lactic acidosis begins (pO2, pCO2, and pH are only maintained until a certain threshold)
84
Why do we have O2 debt (3 reasons)
- To reconvert Lactic acid into Glucose - To replenish O2 stores in Muscles (myoglobin) - To rebuild ATP and creatine-phosphate reserves
85
What is Max CO?
30 L/min (can not increase further) Over the Anaerobic threshold, body cant compensate, so lactic acidosis = lower pH = problems
86
Where is phrenic nerve exit from spinal cord
C4 So any injury above C4 causes no respiration (intercostal at thoracic but breathing can happen without, but not enough)
87
What controls breathing (4)?
- Respiratory control centers - Central chemoreceptors - Peripheral chemoreceptors - Mechanoreceptors
88
Respiratory Control Centers + Place + Nuclei
- In medulla - Ventilatory pattern generator - Integrator - Dorsal, Ventral, Pontine Resp. groups
89
Dorsal respiratory group (DRG)
Inspiration (normal) - Cells in NTS - Dorsomedial - Afferent input from CN IX, X
90
Ventral respiratory group (VRG)
Forced breathing (exercise) - Ventrolateral - Nucleus Retrofecialis (exh) - Nucleus Retroambiguous (inh) - Nucleus Para-ambiguous (both)
91
What controls basic rhythm of breathing
VRG Pre-Botzinger & Botzinger (fine tuning) complexes
92
3 Respiratory centers of brainstem
- Medullary center (V/D/P RG) - Apneustic center (pontine) - Pneumotaxic center (pontine)
93
Apneustic center
Stimulation of prolonged inspiration
94
Pneumotaxic center
Turns off inspiration to prevent over inflation (can live without this center)
95
Breathing Pacemaker Theory
Cells of Botzinger complex in VRG
96
Central Chemoreceptors
- In CSF behind BBB - Sensitive to pCO2 changes - CO2 can pass BBB - Slow & Can adapt
97
Peripheral Chemoreceptors
- In Carotid and Aortic bodies - Sensitive to pO2 drop, pCO2 rise, pH drop, K+ rise - Fast & No adaptation
98
K+ effect on breathing
Higher E.C K+ indicates lots of muscle work so therefore more CO2 is expected to be made and more O2 is being consumed, leading to signaling for increased ventilation
99
Acidosis K+ effect
Higher E.C K+ due to H+ entering cells to compensate for the loss of positive charge = Acidic environment inside cells = Acidosis can cause Hyperkalemia
100
Mechanoreceptors in Lungs
- Stretch receptors - Irritant receptors - Juxtacapillary receptors
101
Hering-Breuer Reflex
Initiation of expiration when the Lungs are stretched to prevent over-inflation