ABSTRACT
Breathing is an intricate, nimble process that is vital to extrauterine life. Numerous components in the brain and periphery are involved in creating a system that can respond instantaneously and effortlessly to meet the oxygen demands of cells and tissues. The transition from fetal to extrauterine life places immediate demands on a complex system. Before birth, breathing is episodic, inhibited by hypoxia and is not necessary for gas exchange. After birth, breathing has to be sustained, has to increase in response to hypoxia and is essential for gas exchange. This chapter reviews the development of the central respiratory network in the brainstem that generates respiratory rhythm and peripheral reflexes in the airways and lungs, and central and peripheral chemoreceptors that modulate those central processes. All components of the respiratory network are still maturing in the neonate, which places the network at risk for delayed or abnormal development in response to adverse environmental exposure, especially for the infant who is born prematurely. Genetic and epigenetic modifications of neurotransmitters and neuromodulators, or developmental disruption of specific neuronal groups in the central network can permanently disrupt normal breathing with significant consequences leading to a less nimble, less responsive respiratory network at risk for failing in response to stressors during a critical period in infancy.
