respiratory - topic 4 Flashcards
what is compliance?
ease of lung expansion (inverse of elastance)
what is resistance?
how easily the air moves in/out
what is emphysema?
lung compliance is too high - lungs don’t bounce back - increase in volume is too high compared to pressure
what is fibrosis?
lung compliance is too low - lungs are too stiff) - increase in volume is too low compared to pressure
what is hysteris?
different pressure volume curves for inspiration vs expiration, due to surface tension being present in inspiration and not expiration
what is the law of laplace?
collapsing pressure is equivalent to the surface tension which is equivalent to the radius
why do small alveoli have high surface tension?
to offset the collapsing pressure
what is surfactant?
mix of proteins and phospholipids that come from type 2 alveolar cells
what does surfactant do?
lowers surface tension to increase compliance and stabilize alveoli
when is surfactant produced in the lifespan?
only late in gestation, causes respiratory distress syndrome in preemies
how is respiratory distress syndrome treated?
corticosteroids or exogenous surfactant
what is Poiseulle’s law?
resistance = (8 x viscosity x length) / (pi x radius ^4)
what factors effect airway resistance?
lung volume
viscosity
autonomic nervous system
histamine, etc that cause bronchoconstriction
how does lung volume affect resistance?
increased lung volume increases airway diameter which decreases resitance
how does viscosity affect resistance?
increased viscosity increases pressure which decreases resistance
how does the nervous system affect resistance?
parasympathetic controls bronchial smooth muscle
parasympathetic can constrict airways
sympathetic can use B2 receptors to decreases resistance
how does He-O2 mix affect reistance?
it decreases it
