Practice question

Main respiratory organ in adult tetrapods is lung paired endodermal outgrowths from ventral foregut undergoing branching morphogenesis forming bronchial tree terminating in alveolar sacs in mammals, parabronchial lungs with air sacs in birds, faveolar lungs in reptiles, sac-like septate lungs in amphibians increasing diffusion surface and surfactant reducing surface tension. Ventilated by aspiration breathing using intercostal and diaphragmatic muscles creating negative intrathoracic pressure. Gills persist only in fish and amphibian larvae, skin supplement amphibians, tracheae insects, thus pulmonary dominance defines tetrapod aerial gas exchange.