Static Mechanisms Flashcards
distending pressure across lung aka
transpulmonary pressure
what is the transpulmonary pressure
difference in pressure between the outside and inside of lung = Alveolar -intrapleural pressures
distensibility aka
compliance
what is lung compliance?
change in volume of lung produced per unit distending pressure
what two factors account for retractive or recoil force of lung?
elastic tissue and surface forces
lung recoil depends on surface tension at –
alveolar air-fluid interface
lung recoil depends on – in alveolar walls and bronchi
elastic and collagen fibers
without surfactant, recoil forces would be –
more powerful
without surfactant, lung ventilation would be –
more difficult
function of surfactant
reduce surface tension and lung recoil
surfactant is a – material that is rich in phospholipid dipalmitol lecithin
lipoprotein
surfactant is synthesized in –
type II alveolar cells
where is surfactant extruded?
alveoli surface
surfactant – the tendency of smaller alveoli to empty in larger ones
counter
surfactant prevents – into alveoli from pulmonary capillaries
transudation of fluid
when is surfactant formed?
late in fetal life
in premature births, insufficient surfactant is available or inactive which leads to –
neonatal respiratory distress syndrome = stiff lungs, collapsed alveoli
reduced lung elastic recoil –> chest wall moves –
out
increased lung elastic recoil –> chest wall moves –
in
At residual volume, elastic recoil of chest wall is directed outward is –
large (inward is small)
at functional residual capacity, elastic recoils of lung and chest are –
equal but opposite
at larger lung volume, elastic recoil of chest wall becomes – and recoil of lung –
recoil of chest wall decreases and recoil of lung increases
at approximately 70% of total lung capacity, equilibrium position of – (its recoil is 0)
chest wall
at total lung capacity, elastic recoil of both lung and chest wall directed – favoring a decrease in lung volume
inward
