Physiology: Surfactant, Compliance and Lung function tests Flashcards
What is surfactant?
detergent like fluid which reduces surface tension
What is surface tension?
attraction of water molecules which is seen in a air - water interface
What cells produce surfactant
Type II alveolar cells
What does surfactant do in the lungs? (5)
Reduces tendency for alveoli to collapse
Increases lung compliance
Reduces lungs tendency to recoil
Makes breathing work easier
More effective in smaller alveoli as the surfactant molecules are close together
When does surfactant production start and finish in embryos?
~25 week it starts and finishes ~36 week mark
What is the production of surfactant stimulated by in embryos?
Thyroid hormones and cortisol
What respiratory problem do some premature babies suffer from?
Infant Respiratory Distress Syndrome (IRDS)
What fills the alveoli in utero?
Saline
What is the definition of compliance?
how much of a volume change for any give change in pressure
Ie how stretchable the lungs are
What does a high compliance in the lungs mean?
large increase in lung volume for a small decrease in ip pressure
What does low compliance mean?
Small increase in lung volume for a large decrease in ip pressure
What is emphysema and what respiratory effort is required?
Loss of elastic tissue
Expiration requires a lot of effort
What is Fibrosis and what respiratory effort is required?
Inert fibrous tissue
Inspiration requires an increase in effort
What is the difference in pressure volume relationship at different areas of the lungs?
at the base the volume change is greater for any given change in pressure when compared to the apex of the lung
Where is alveolar ventilation greatest when compared in the lungs?
Greatest at the base when compared to the apex
