Glycinergic and GABAergic inhibitory neurons make up half of all inspiratory neurons. Exposure of the pre-Bötzinger complex to these inhibitory neurotransmitters results in the rhythmic nature associated with respiration. Blocking this inhibition from Glycine or GABA causes its neurons to be incapable of switching from the active phase to the inspiration phase, demonstrated by shorter inspiratory activity (as seen in vivo). However, the absence of inhibitory synapses still resulted in rhythmic respiratory activity in vitro and in situ. This is largely due to the fact that respiratory rhythm results from numerous aspects, with synaptic inhibition playing only a single part.