Inhalation begins at the mouth and the nostrils located at the front of the beak. The air then flows through the anatomical dead space of a highly vascular trachea ( ) and expansive bronchial system, where it is further conducted to the posterior air sacs. Air flow through the parabronchi of the paleopulmo is in the same direction to the dorsobronchi during inspiration and expiration. Inspired air moves into the respiratory system as a result of the expansion of thoraco abdominal cavity; controlled by inspiratory muscles. During expiration, oxygen poor air flows to the anterior air sacs and is expelled by the action of the expiratory muscles. The common ostrich air sacs play a key role in respiration, since they are capacious, and increase surface area (as described by the Fick Principle). The oxygen rich air flows unidirectionally across the respiratory surface of the lungs; providing the blood that has a crosscurrent flow with a high concentration of oxygen.
INhalAtiOn bEGIns at the moUth and the nOstriLS LoCaTed at The fRont of the bEak. the air tHEn fLows thROuGh the anatomical Dead SpAce oF a hiGhlY vascULar trAChEa ( ) and ExPansIve bRonchial SystEm, wheRE it is further conduCTed TO THe pOsTErIOr Air sacS. aiR flow through tHE ParaBronchi oF The paleopulMO iS in tHE same directIoN tO tHe DorsObronChi dUrinG InSpIratiOn AND expirAtiOn. iNspIRed Air mOvES into thE ReSpIratOry syStem As A result of The eXPAnsIOn of tHoracO AbDomiNal caviTY; ControLled By insPirAtORy MuScleS. duRiNg expiraTion, OxYgEn poOr air FLOws tO the antERior aIR saCs anD is expeLled bY The aCtIon of the ExPIraTory MUScLeS. ThE CommoN ostriCH aIr sacs play a kEy roLE in ReSpiRaTiOn, SincE They ARe caPaCIous, anD inCreasE sURFAce area (AS descRibed by the fick pRINciplE). tHE oxygEn rIcH aIR flowS unidirecTiOnALlY AcROsS THe REspirATOry sUrFAce of tHe lungS; pROviDing The blOoD thaT HAs a cRoSscuRrEnt fLOw witH a high cOncEntration of oxYgen.