ABSTRACT
Feedback control of breathing, based on control of respiratory depth and timing, serves to regulate arterial blood gas tensions within limits consistent with tissue function, respiratory energy cost, and perceived discomfort. Respiratory control in adult humans and animals involves complex interactions among humoral and neural reflex processes, and behavioral reactions acting through the respiratory muscles on the mechanics of the respiratory pump. Each of these factors is affected directly or indirectly by perturbations in the mechanical characteristics of the respiratory muscles, airways, and gas exchanger, whether the mechanics are altered by the applicaton of external loads, or by changes in mechanics intrinsic to the respiratory system. The respiratory system responds passively to load perturbations through intrinsic characteristics, and may respond actively by means of reflexes reacting to afferent nerve information.
