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20 terms

Expiration (Exhalation)

STUDY
PLAY
alveolar pressure at end of inspiration
equals Patm
for expiration
Palv must exceed Patm
if decrease volume of thoracic cavity
Palv will increase and outward flow of air can occur
expiration may be
active or passive
forces that act on the respiratory system
active and passive - both will affect Palv
passive
recoil force of lung-thorax unit - quiet breathing
active
applied muscle force
Passvie Forces of Exhalation
gravity, relaxation, elasticity, torque - cause the lungs to recoil
Gravity
pulls rib cage downward
Relaxation
of the contracting muscles, including the diaphragm (returns to dome shape)
Elasticity
of the respiratory tissues and lungs
Torque
of the ribs (ribs untwist as they return to their original positions
As volume decreases
Palv surpasses Patmos & air rushes out of the lungs
Palv needs to become
positive
Diaphragm
relaxes back to its dome shape - Decreases vertical dimension
External intercostals
relax - Decreases front-to-back and side-to-side dimensions
lung
size decreases b/c of elastic recoil
positive flow
air moving out
negative flow
air moving in
Active forces of exhalation
Contraction of abdominal muscles during speech