Resp Physiology

force per unit area cmH₂O

• pressure
• Molecules move and collide into one another and the walls of the container they are in.

•the sum of the forces of collision divided by the area of the container’s walls.

–change in pressure across containers.

•Alveolar pressure – pressure within the lungs.

•Pleural pressure – pressure within the pleural space.

•Abdominal pressure – pressure within the abdominal cavity.

• when volume inside lungs is low, the pressure is high (expiration)
• when volume inside lungs is high, the pressure is low (inspiration)
• always looking for balance

–Alveolar pressure is lower than atmospheric pressure  (INSPIRATION)

–Alveolar pressure is GREATER than atmospheric pressure (EXPIRATION)

airflow is increased as well

–Volume (L), Changes (sec) = Airflow = l/s

• spirometer,
• all volumes are measured directly except for residual volume which is computed
• all capacities are a combo of 2 or more volumes

volume of air exchanged during rest breathing

•maximum volume of air which can be inspired after a tidal inspiration.

•maximum volume of air which can be inspired after a tidal inspiration.

•maximum volume of air which can be expired after a tidal expiration.

amount of air left in the lungs after a maximum expiration

•: total amount of air which can be held in the lungs (all volumes added together).

•maximum volume of air which can be inspired after a tidal expiration (tidal volume + inspiratory reserve volume).

•maximum amount of air which can be inspired after a maximal expiration (tidal volume + inspiratory reserve volume + expiratory reserve volume OR total lung capacity – residual volume).

–Often express lung volume in terms of %VC

•amount of air in lungs after a tidal expiration (expiratory reserve volume + residual volume).

• END EXPIRATORY LEVEL
• important ref point in resp physiology
• lung volume measured at the rest point of resp-at the end of a tidal volume expiration at the top of FRC

Different from REL.  REL is the actual physiologic point; EEL is the measurement of that point (differs slightly

the lungs must be expanded or contracted

• recoil of the lung-thorax unit (passive)
• muscle force (active)

how these mechanisms are used depends on the volume of air in the lungs

• INS
• always caused by active muscle forces

• EXP
• is passive during rest breathing
• is a mix of active and passive forces during speech

• they are elastic they resist being deformed from rest
• they also exert a force to return to rest-elastic recoil force
• they have individual rest positions

• the lungs deflate to their rest position fully deflated (0% VC)
• the rib cage moves to its rest position-partially inflated (55%VC)
• when coupled the rest position (at REL) is 35-40%VC

• pressures within the lung and are a source of power for the speech system
• recoil forces are proportional to the amount of distortion

inspiratory and expiratory muscles

all of the pressure put together, active and passive forces