Flashcards in lung mechanics Deck (19):
how does a gas move
high to low P
what muscles are involved in inspiration
diaphragm, intercostals, accessory muscles (scalene and SCM)
what point are lungs at after normal exp.
muscles for forced expiration
abs and internal intercostals
function of pleaura (2)
1. transmit pressure
2. allow movement
what is typical pleural pressure at FRC
when does pleural pressure become positive
what happens to lung volumes as pleural pressue become more neg.
what happens to alveolar elastic in emphysema and fibrosis
emphysema - destroyed
fibrosis - increased
formula for compliance
change in V/change in P
how does lung compliance change with volumes?
less compliant at very high or low volumes
what can create stiff chest wall
obesity, burns, binders, drugs, mulitrib fractures
what 3 things determine lung vol.
1. chest wall compl.
2. lung compliance
3. resp. muscle strength
what is formula for laPlaces law for spheres
take away from laPlace
the smaller the radius, the higher the pressure -- gas wants out
what does surface tension on surfactant depend upon?
what is purpose of surfactant
helps stabilize the sphere size so doesn't get too big
** what are 3 purposes of sufactant
1. stabilizes small alveoli
2. less tension = less breathing work
3. keeps lungs dry