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Fundamentals of Physiology > L10: Lung Function > Flashcards

L10: Lung Function Flashcards

1
Q

1st step in respiration

A

Respiration: Movement of air in & out of lungs by bulk flow (down a diffusion gradient)

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2
Q

2nd step of respiration

A

Exchange of O2 & CO2 between alveolar air & blood in lung capillaries by diffusion

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3
Q

3rd step of respiration

A

Transport of O2 & CO2 through pulmonary & systemic circulation by bulk flow

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4
Q

4th step of respiration

A

Exchange of O2 & CO2 between blood in capillaries & respiring tissues by diffusion

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5
Q

5th step of respiration

A

Cellular utilisation of O2 & production of CO2

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6
Q

How does air flow occur?

A

From a region of high pressure to a region of low pressure

Air flow is proportional to the different in air pressure

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7
Q

Define ventilation

A

Flow of air in & out of lungs

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8
Q

How to calculate total ventilation per minute (VE)??

A

Breathing rate (R) x Tidal volume (VT)

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9
Q

What is the pressure difference between in lungs?

A

Atmospheric (Patm) & alveolar (Falv)

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10
Q

Define Boyles Law

A

Pressure is inversely proportional to volume

  • A change in volume induces a change in pressure

Pressure decreased - Volume increased
Volume decreased - Pressure increased

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11
Q

What is the change in volume caused by?

A

Respiratory muscle

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12
Q

Mechanism of breathing in

A
  • Diaphragm pulls down (contracts)
  • Chest volume increases
  • Pressure decreases
  • Air flows in
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13
Q

Mechanism of breathing out

A
  • Diaphragm moves up (relaxes)
  • Chest volume decreases
  • Pressure increased
  • Air flows out
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14
Q

Inspiration & expiration at rest

Diaphragm & External Intercostals

A

Inspiration: Diaphragm & external intercostal contract

Expiration: Diaphragm relaxes + recoil of lungs

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15
Q

Inspiration & expiration during exercise

Diaphragm & Internal Intercostals

A

Inspiration: Forceful contraction of diaphragm

Expiration: Abdominals + Internal intercostals contract

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16
Q

What does rib movement allow the chest to do?

A

Expand in 3D

Expansion of chest cavity causes expansion of the lungs

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17
Q

Function of pleural fluid

A

Creates cohesion between lungs & chest walls

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18
Q

Is the intrapleural pressure (PIP) positive or negative?

A

Negative

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19
Q

How does expansion of chest cavity cause expansion of the lungs?

A

1) Pressure between the pleura & intrapleural pressure (PIP) is slightly negative
2) As chest cavity expands, PIP becomes MORE NEG
3) Followed by expansion of the lungs

Lungs stretch during inspiration, elasticity allow recoiling

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20
Q

How does air flow into lungs during inspiration?

A

1) Diaphragm & muscles contract, increasing volume of chest cavity
2) PIP falls
3) Alveoli expands
4) Palv falls
5) Pressure difference occurs (Palv < Patm)
6) Air flows into lungs

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21
Q

What does lung compliance refer to the ability of?

A

The ability of the lungs to stretch & expand

22
Q

Define compliance

A

How ‘stretchable’ a tissue is

23
Q

How easily lungs can be expanded by a given change in pressure determines….

A

How much work must be done by respiratory muscles

24
Q

Equation for lung compliance

A

Change in lung volume / Change in trans-pulmonary pressure

25
Define total lung capacity (TLC)
Maximum breath in
26
Define functional residual capacity (FRC)
End of normal breath out
27
Define residual volume (RV)
Max breath out
28
Equation for lung compliance
Change in volume pressure / Change in trans-pulmonary pressure
29
Define transpulmonary pressure
Force that makes lungs expands ## Footnote Increases when PIP decreases
30
What influences lung compliance?
Connective Tissue Surface Tension ## Footnote Too much connective tissue = low compliance Too little connective tissue = high compliance
31
Excess collagen is a feature of which disease?
Restrictive lung disease
32
Loss of connective tissue is a feature of which disease?
Obstructive lung disease
33
How does low compliance result in impaired gaseous exchange where inspiration is RESTRICTED?
Low compliance - More effort needed to expand lungs when breathing in - Lung capacity reduced Impaired gaseous exchange
34
How does high compliance result in impaired gaseous exchange where expiration is OBSTRUCTED?
High compliance - Bronchioles collapse easily during expiration - Stale air trapped in alveoli - Impaired gaseous exchange
35
Define surface tension
Product of cohesion forces between H2O molecules being strongest at air-water interface
36
Equation for alveolar air pressure (P), tension (T) & radius of alveolus (r)
P = 2T / r
37
Does surface tension reduce or increase compliance?
Reduce, opposing alveolar expansion
38
What is surface tension reduced by to maintain compliance?
Surfactant secreted by type II pneumocytes
39
What is the absence of surfactant a complication in?
Premature birth
40
Define airway resistance
Properties of the aiways that limit flow of air through them ## Footnote Important in bronchi & bronchioles
41
Does constriction of bronchioles increase OR decrease airway resistance?
Increases
42
Is flow inversely proportional OR proportional to resistance?
Inversely proportional
43
Define bronchoconstriction
Constriction of airways in the lungs due to tightening of surrounding smooth muscle
44
Define bronchodilation
Widening of aiways, easier to breath
45
3 factors that influence the radius of bronchioles
1) Neuronal 2) Hormonal 3) Paracrine
46
2 examples of **paracrine factors** influencing radius of bronchioles
CO2, Histamine
47
1 example of **hormonal factors** influencing radius of bronchioles
Adrenaline (in blood)
48
1 example of **neuronal factors **influencing radius of bronchioles
Acetylcholine
49
Excessive narrowing of bronchioles is a feature of what disease?
ASTHMA & obstructive lung disease
50

Fundamentals of Physiology (19 decks)

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