5 pressures and compliance Flashcards
What is quiet respiration?
occurs only using the diaphragm?
What is Boyle’s Law?
P(1) x V(1) = P(2) x P(2)
Why is there negative pressure in the pleural space?
lungs want to move inwards, thorax wants to move outwards
What is the pleural liquid pressure?
intrapleural pressure, insuring mechanical coupling
Why do the pleura not touch?
repulsive forces between fatty acid groups of the lipid bilayer
What happens to P(pl) and P(A) during expiration?
they increase
Which is bigger, P(A) or P(pl)?
P(A), always, as the pressure gradient helps move oxygen
When does airflow stop?
When P(A) = 0
What happens to the P(A) : P(pl) when ventilation is increased?
it increases
What is compliance?
how stretchy, or distensible an elastic substance is
What is compliance equal to?
change in V / change in P
When might P(pl) be positive?
in forced expiration
On a compliance curve, where is compliance greatest?
around FRC, where there is the largest gradient
What happens to lung compliance as we reach TLC?
it reduces
What is the total system compliance equal to?
1 / TSC = 1 / C(L) + 1 / C(W)
total system compliance is twice as stiff as its’ components
