[Recent concepts of respiratory regulation (author's transl)]

There are two functional aspects of the respiratory control system, the one being adaptation of ventilation to metabolic needs and the other acid-base homeostasis of the extracellular fluid of the brain. These two functions are perfectly compatible with one another under normal conditions. During hypoxia or hyperthermia, however, a compromise has to be reaches by the system between securing oxygen availability or homeothermy, respectively and acid-base homeostasis of the brain. The control system works with tonic chemosensitive and non-chemosensitive neural input of action potentials to the centres. The centres, either by indigenous mechanisms or by phasic reflex input from the stretch receptors of the lungs or phasic feedback mechanisms from the pontine pneumotaxic centre, modulate the tonic impulse input into the rhythmic output to the respiratory muscles. Recent observations on this "inspiratory off switch mechanism" are discussed. Chemosensitive sensors are found in the carotid and aortic glomera responding to low pO2 and, additionally, to pH and pCO2 and in central chemosensitive structures on the ventral side of the medulla oblongata, responding mainly to changes in local hydrogen ion concentration. The proprioceptive reflexes in the sense of a gamma loop improve the performance of the system if additional flow resistance must be overcome. In metabolic and respiratory acidosis-alkalosis the kidney either plays a compensatory role or serves to restore normal conditions. The maternal hormones in pregnancy effect air improvement in CO2 output of the fetus.