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Respiratory Physiology Flashcards

(58 cards)

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1
Q

What respiratory cell
produces protective
glycosaminoglycans and
metabolizes air-borne toxins?

A

Clara cells (Club Cells)

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2
Q

What respiratory cell
removes particles trapped in
the alveoli?

A

Dust cells (Alveolar
Macrophages)

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3
Q

What respiratory cell
comprises 96-98% of the
alveoli surface area?

A

Type I Pneumocyte
For gas exchange

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4
Q

Why is pulmonary flow less
than the systemic flow?

A

because about 2% of the
systemic cardiac output
bypasses the lungs
The pulmonary circulation has lower pressure and lower resistance than the systemic circulation

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5
Q

This refers to the air in the
conducting zones that do not
undergo gas exchange:

A

Anatomic Dead Space
Air from the Nose to Terminal Bronchioles (150 ml)

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6
Q

This air space is normally
equal to the anatomic dead
space volume:

A

Physiologic Dead Space
Anatomic (150mL) + Alveolar Dead Space (0mL)

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7
Q

The formula for minute ventilation:

A

Tidal volume x breaths/min

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8
Q

The formula for alveolar ventilation:

A

(tidal volume – physiologic dead space) x breaths/min

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9
Q

Lung volume and Capacity: Amount of air inhaled or exhaled during the relaxed state

A

Tidal Volume
Normal Value: 500mL divided into: anatomic dead space (150mL) respiratory unit of the lung (350mL)

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10
Q

Lung volume and Capacity:
Remaining air in the lungs after maximal exhalation

A

Residual Volume

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11
Q

Lung volume and Capacity:
Maintains oxygenation in between breaths

A

Residual Volume

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12
Q

Lung volume and Capacity: air
in the lungs after expiring tidal volume

A

Functional Residual Capacity
Marker of lung function

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13
Q

Lung volume and Capacity:
alveolar pressure = atmospheric pressure

A

Functional Residual Capacity
Marker of lung function

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14
Q

Compute for the ERV:
Vital Capacity – 5L
Tidal Volume – 0.5L
Ins. Capacity – 3.5L
FRC – 2.5”

A

1.5 L
ERV = Vital capacity minus inspiratory capacity

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15
Q

FRC in patients with
obstructive lung diseases:

A

High

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16
Q

FEV1/FVC in patients with restrictive lung diseases:

A

Normal or high

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17
Q

FEV1/FVC in patients with obstructive lung diseases:

A

Low

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18
Q

What is the primary drive to breathe in COPD patients?

A

Hypoxic Drive
Low PaO2 stimulating peripheral
chemoreceptors.

Hypercapnic drive is blunted due to compensated respiratory acidosis

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19
Q

What is the main muscle active during normal inspiration?

A

Diaphragm

Forced Inspiration: External Intercostals,
Accessory Muscles: SCM, Anterior Serrati, Scalene, Alae Nasi, Genioglossus, Arytenoid

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20
Q

What is the main muscle active during normal expiration?

A

None – Passive normal expiration

Forced Expiration: Internal Intercostals, Abdominal muscles (Rectus Abdominis, Internal and External Oblique, Transversus Abdominis)

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21
Q

This refers to the distensibility of the lungs and chest wall:

A

Compliance

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22
Q

Where in the pressure-volume
curve is compliance the highest?

A

Middle range pressures

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23
Q

Complete: Lungs have the
natural tendency to _____ as to
the chest wall’s tendency to __

A

Collapse; Expand

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25
According to the Law of Laplace, why are pre-term babies prone to high collapsing pressure?
due to: Smaller alveolar radius Lack mature surfactant Collapsing pressure is DIRECTLY proportional to the surface tension and INVERSELY proportional to the alveoli radius
26
What is the main component of surfactant?
Water
27
What is the active component of surfactant?
DPPC (Dipalmitoyl Phosphatidylcholine)
28
What formula is the basis for airway resistance?
Poiseuille Law Resistance is DIRECTLY proportional to blood viscosity and vessel length, while INVERSELY proportional to vessel radius
29
What is the effect of the sympathetic nervous system on the bronchial smooth muscles?
Bronchodilation
30
What is the effect of histamine on the bronchial smooth muscles?
Bronchoconstriction
31
What is the effect of hypoxia on the pulmonary vascular bed?
Vasoconstriction Shunts blood away from unventilated areas of the lung, where it would be wasted
32
What is the partial pressure of oxygen in the mixed venous blood?
40 mmHg Dry inspired air: 160 mmHg Humidified Tracheal Air: 150 mmHg Alveolar Air: 100 mmHg Systemic Arterial Blood: <100 mmHg
33
What happens before inspiration (breathing cycle)?
Intrapleural pressure is negative, alveolar pressure = 0
34
What happens during inspiration (breathing cycle)?
Intrapleural pressure becomes more negative, alveolar pressure becomes more negative
35
What type of gas exchange where gas equilibrate with the pulmonary capillary near the start of the pulmonary capillary?
Perfusion-limited Gas Exchange N2O, O2, CO2 under normal conditions
36
What are examples of substances that undergo diffusion-limited gas exchange?
CO and O2 during strenuous exercise and disease states (emphysema, fibrosis) Gas Does NOT equilibrate even until the end of the pulmonary capillary
37
How is oxygen transported 98% of the time?
98%: transported via hemoglobin (Hgb) 2%: transported freely dissolved in plasma
38
What is the composition of adult hemoglobin (chains)?
2 alpha & 2 beta chains Fetal Hemoglobin (HbF): 2 alpha & 2 gamma chains
39
What is this phenomenon where binding of the first O2 molecule increases affinity for the second O2 molecule and so forth?
Positive Cooperativity (O2-HgB DISSOCIATION CURVE)
40
In the O2-Hg dissociation curve, what are the factors that shift the curve to the right?
Carbon DIOXIDE, Acidosis (Bohr Effect), 2,3 BPG, Exercise & Temperature
41
In the O2-Hg dissociation curve, what happens to the P50 and oxygen affinity, respectively, when the curve shifts to the right?
P50 increases; affinity decreases
42
In the O2-Hg dissociation curve, what happens to the oxygen binding (with hemoglobin) when the curve shifts to the left?
Increased binding of O2 with Hgb
43
This refers to decreased tissue PO2:
Hypoxia Not always caused by hypoxemia
44
This refers to decreased arterial PO2:
Hypoxemia Will lead to hypoxia
45
What are the two causes of hypoxemia with a decreased PaO2 but NORMAL A-a gradient?
High Altitude Hypoventilation Decreased PaO2 with High A-a gradient: V/Q defect, diffusion defect, right-to-left shunt
46
What are the three ways the body transports CO2?
70%: HCO3- 23%: CarbaminoHgb 7%: freely-dissolved in plasma
47
In the CO2 transport, what is the principal buffer in the interstitial fluid?
Carbonic Acid
48
What is the effect of low PAO2 on pulmonary arteries?
Vasoconstriction
49
What is the PO2 and PCO2 level in patients with high V/Q?
high PO2, low PCO2 (e.g., lung apex) Normal V/Q Ratio: 0.8 Low V/Q: low PO2, high PCO2 (e.g., lung base)
50
What is the V/Q of a patient with blood flow obstruction?
V/Q = Infinite (Dead Space) like pulmonary embolism V/Q = Zero or Shunt (e.g., R-L shunt, airway obstructions)
51
Respi-Control Center: Generates basic rhythm for breathing, for normal and/or resting inspiration
DRG
52
Respi-Control Center: for forced inspiration and expiration (overdrive mechanism)
VRG
53
Respi-Control Center: Effect of pneumotaxic center on the respiratory rate
Increase RR Location: Upper Pons Shortens time for inspiration → ↑ RR
54
Respi-Control Center: What does the apneustic center do with the inspiration time?
Prolongs inspiration time Location: Lower Pons This, decreases RR
55
The central chemoreceptors respond DIRECTLY to which factor that increases the RR?
CSF H+
56
The peripheral chemoreceptors respond MAINLY to which factor to increase the RR?
PaO2 <60mmHg Location: Carotid and Aortic Bodies
57
In a high altitude, what happens to the Alveolar and Arterial PO2?
Decreases Increases: RR, arterial pH, HgB, 2,3 BPG, pulmonary vascular resistance
58
What happens to the arterial PO2 and PCO2 during exercise?
No change Increases: O2 Consumption, CO2 Production, RR, Venous PCO2, Pulmonary Blood Flow Decreases: Arterial pH (strenuous exercise due to lactic acidosis)

PHYSIOLOGY (9 decks)

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