PHYS20008 Lecture 20: PHYS20008 Lecture 20
10 May 2018
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Lecture 20
- Airway resistance increases with an increase in the length of the airway, increase in
the viscosity of air, decrease in the airway diameter
- Viscosity is resistance to flow
- Humidity increases viscosity of air
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- Factors we aren’t controlling: mucus built up → harder to breathe, narrow airways →
increase resistance
- Physical obstructions can affect air resistance in upper airways
- Factors we can control: bronchioles and lower airways with smooth muscle
- Radius of vessel going through has big impact on resistance
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- Airway resistance: how hard is it to push air through the tube
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- Lung compliance: how easily it accommodates air, stiff and rigid → difficult to inflate→
increase work of breathing
- Affected by disease states
- Affect the passage (as in width) to increase work of breathing by affecting resistance
- Affect the pump by making it more difficult to inflate lungs
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- Lung compliance: ability of lung to inflate, ability to accommodate air, how easy it is
to blow lung up, pulmonary fibrosis stiffens walls of alveoli and lungs → more difficult
to inflate
- Lung elastance: ability of lung to spring back after it’s been inflated, recoil, affected
by emphysema → breaks down elastin fibres → more difficult to exhale (hard to inhale
because haven’t emptied lungs efficiently)
- If lung compliance increases, then lung elastance will not always increase
- Paper bag is compliant but less elastic, balloon is harder to inflate but more elastic
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find more resources at oneclass.com
Document Summary
Airway resistance increases with an increase in the length of the airway, increase in the viscosity of air, decrease in the airway diameter. Factors we aren"t controlling: mucus built up harder to breathe, narrow airways increase resistance. Physical obstructions can affect air resistance in upper airways. Factors we can control: bronchioles and lower airways with smooth muscle. Radius of vessel going through has big impact on resistance. Airway resistance: how hard is it to push air through the tube. Lung compliance: how easily it accommodates air, stiff and rigid difficult to inflate increase work of breathing. Affect the passage (as in width) to increase work of breathing by affecting resistance. Affect the pump by making it more difficult to inflate lungs. Lung compliance: ability of lung to inflate, ability to accommodate air, how easy it is to blow lung up, pulmonary fibrosis stiffens walls of alveoli and lungs more difficult to inflate.
