Lung volume reaches its minimum for the respiratory

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Unformatted text preview: volume and (dal volume –  Maximum amount of air that can be voluntarily moved in or out of system with one breath •  “take in as much air as possible, then blow it all out” •  Vital Capacity + residual volume = Total Lung Capacity –  Decreases with age as muscles weaken and lungs become less elas(c •  Inspiratory capacity ((dal + IRV) •  Func(onal residual capacity (ERV + residual volume) Ven(la(on •  For air to move into alveoli, pressure inside lungs must become lower than atmospheric pressure –  During inspira(on, thoracic volume increases when muscles of rib cage (25- 40%) and diaphragm (60- 75%) contract Atmospheric pressure is assigned 0 0 – In the brief (me between breaths, alveolar pressure is equal to atmospheric pressure = no air flow 0- 2: Inspira(on – As Inspira(on begins, muscles contract and thoracic volume increases leading to alveolar pressure decrease below atmosphere and air flow into alveoli. Because the thoracic volume changes faster than air can flow, alveolar pressure reaches its lowest value about halfway through the inspira(on 0- 2: Inspira(on, con(nued As air con(nues to enter alveoli, pressure increases un(l thoracic cage stops expanding, just at end of inspira(on Air movement con(nues for a frac(on longer un(l pressure inside lungs equalizes with atmospheric pressure (point A3) 2- 4: Expira(on- Diaphragm and rib cage return to normal relaxed posi(ons, volume of lungs decreases. Air pressure in the lungs...
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