Reflex arc A reflex action happens quickly because the reflex pathway is kept short and involves the smallest number of neurones and synapses possible.

Reference: Lovelace JW, Ma J, Yadav S, et al. Vagal sensory neurons mediate the Bezold–Jarisch reflex and induce syncope. Nature. 2023. doi: 10.1038/s41586-023-06680-7 ...